21100G.book

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 2004 Microchip Technology Inc.

DS21100G-page  1

FEATURES

• Single supply with operation down to 1.8V
• Low power CMOS technology

- 1 mA active current typical
- 10 

µ

A standby current typical at 5.5V

- 5 

µ

A standby current typical at 3.0V

• Organized as 8 blocks of 256 bytes (8 x 256 x 8)
• 2-wire serial interface bus, I

2

C

 compatible

• Functional address inputs for cascading up to 8 

devices

• Schmitt trigger, filtered inputs for noise suppres-

sion

• Output slope control to eliminate ground bounce
• 100 kHz (1.8V) and 400 kHz (5V) compatibility
• Self-timed write cycle (including auto-erase)
• Page-write buffer for up to 16 bytes
• 2 ms typical write cycle time for page-write
• Hardware write protect for entire memory
• Can be operated as a serial ROM
• Factory programming (QTP) available
• ESD protection > 4,000V
• 1,000,000 Erase/Write cycles guaranteed
• Data retention > 200 years
• 8-pin DIP, 8-lead SOIC packages
• Available for commercial temperature range

DESCRIPTION

The Microchip Technology Inc. 24AA164 is a cascad-
able 16K bit Electrically Erasable PROM.  The device
is organized as eight blocks of 256 x 8-bit memory with
a 2-wire serial interface. Low voltage design permits
operation down to 1.8 volts (end-of-life voltage for most
popular battery technologies) with standby and active
currents of only 5 

µ

A and 1 mA respectively. The

24AA164 also has a page-write capability for up to 16
bytes of data. The 24AA164 is available in the standard
8-pin DIP and 8-lead surface mount SOIC packages.

The three select pins, A0, A1, and A2, function as chip
select inputs and allow up to eight devices to share a
common bus, for up to 128K bits total system
EEPROM.

- Commercial (C):

0°C to +70°C

PACKAGE TYPES

BLOCK DIAGRAM

24
A

A

1

6

4

A0

A1

A2

V

SS

1

2

3

4

8

7

6

5

V

CC

WP

SCL

SDA

24A

A164

A0

A1

A2

V

SS

1

2

3

4

8

7

6

5

V

CC

WP

SCL

SDA

PDIP

8-lead
SOIC

HV GENERATOR

EEPROM ARRAY 

(8 x 256 x 8)

PAGE LATCHES

YDEC

XDEC

SENSE AMP 

R/W CONTROL

MEMORY 

CONTROL 

LOGIC

I/O 

CONTROL 

LOGIC

WP

SDA

SCL

V

CC

V

SS

A0

A2

A1

24AA164

16K 1.8V Cascadable I

2

C

 Serial EEPROM

I

2

C is a trademark of Philips Corporation.

Obsolete Device

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24AA164

DS21100G-page  2

 2004 Microchip Technology Inc.

1.0

ELECTRICAL CHARACTERISTICS

1.1

Maximum Ratings*

V

CC

...................................................................................7.0V

All inputs and outputs w.r.t. V

SS..................

-0.3V to V

CC

 +1.0V

Storage temperature .....................................-65°C to +150°C
Ambient temp. with power applied ................-65°C to +125°C
Soldering temperature of leads (10 seconds) ............. +300°C
ESD protection on all pins

..................................................≥

 4 kV

*Notice: Stresses above those listed under “Maximum ratings”
may cause permanent damage to the device.  This is a stress rat-
ing only and functional operation of the device at those or any
other conditions above those indicated in the operational listings
of this specification is not implied.  Exposure to maximum rating
conditions for extended periods may affect device reliability.

TABLE 1-1:

PIN FUNCTION TABLE

Name

Function

V

SS

Ground

SDA

Serial Address/Data I/O

SCL

Serial Clock

WP

Write Protect Input

V

CC

1.8V to 6.0V Power Supply

A0, A1, A2

Chip Address Inputs

TABLE 1-2:

DC CHARACTERISTICS

FIGURE 1-1:

BUS TIMING START/STOP

V

CC

 = 1.8V to +6.0

Commercial (C):  Tamb = 0°C to +70°C

Parameter

Symbol

Min

Typ

Max

Units

Conditions

WP, SCL and SDA pins:

High level input voltage

V

IH

.7 V

CC

V

Low level input voltage

V

IL

.3  V

CC

V

Hysteresis of Schmitt trigger inputs

V

HYS

.05 V

CC

V

(Note) 

Low level output voltage

V

OL

.40

V

I

OL 

= 3.0 mA, V

CC 

= 1.8V

Input leakage current

I

LI

-10

10

µ

A

V

IN 

= .1V to V

CC

Output leakage current

I

LO

-10

10

µ

A

V

OUT 

= .1V to V

CC

Pin capacitance 
(all inputs/outputs

C

IN

C

OUT

10

pF

V

CC

 

= 5.0V (Note 1)

Tamb = 25°C, F

CLK 

= 1 MHz

Operating current

I

CC

 

Write

I

CC

 

Read




0.5

0.05

3

1

mA
mA
mA
mA

V

CC

 

= 5.5V, SCL = 400 kHz

V

CC

 

= 1.8V, SCL = 100 kHz

V

CC

 

= 5.5V, SCL = 400 kHz

V

CC

 

= 1.8V, SCL = 100 kHz

Standby current

I

CCS




3

100

30

µ

A

µ

A

µ

A

V

CC

 

= 5.5V, SDA = SCL=V

CC

V

CC

 

= 3.0V, SDA = SCL=V

CC

V

CC

 

= 1.8V, SDA = SCL=V

CC

WP = V

SS

Note:

 This parameter is periodically sampled and not 100% tested.

T

SU

:

STA

T

HD

:

STA

V

HYS

T

SU

:

STO

START

STOP

SCL

SDA

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 2004 Microchip Technology Inc.

DS21100G-page  3

24AA164

TABLE 1-3:

AC CHARACTERISTICS

FIGURE 1-2:

BUS TIMING DATA

Parameter

Symbol

STANDARD

MODE

V

CC

 

= 4.5-5.5V

FAST MODE

Units

Remarks

Min

Max

Min

Max

Clock frequency

F

CLK

100

400

kHz

Clock high time

T

HIGH

4000

600

ns

Clock low time

T

LOW

4700

1300

ns

SDA and SCL rise time

T

R

1000

300

ns

(Note 1)

SDA and SCL fall time

T

F

300

300

ns

(Note 1)

START condition hold 
time

T

HD

:

STA

4000

600

ns

After this period the first 
clock pulse is generated

START condition setup 
time

T

SU

:

STA

4700

600

ns

Only relevant for repeated 
START condition

Data input hold time

T

HD

:

DAT

0

0

ns

Data input setup time

T

SU

:

DAT

250

100

ns

STOP condition setup 
time

T

SU

:

STO

4000

600

ns

Output valid from clock

T

AA

3500

900

ns

(Note 2)

Bus free time

T

BUF

4700

1300

ns

Time the bus must be free 
before a new transmission 
can start 

Output fall time from V

IH

 

min to V

IL

 max

T

OF

250

20 + 0.1 

C

B

250

ns

(Note 1), C

B

 

 100 pF

Input filter spike suppres-
sion (SDA and SCL pins)

T

SP

50

50

ns

(Note 3)

Write cycle time

T

WR

10

10

ms

Byte or Page mode

Endurance

1M

1M

cycles

25°C, Vcc = 5.0V, Block 
Mode ((Note 4)

Note 1: Not 100% tested.  C

B

 = total capacitance of one bus line in pF.

2: As a transmitter, the device must provide an internal minimum delay time to bridge the undefined region 

(minimum 300 ns) of the falling edge of SCL to avoid unintended generation of START or STOP conditions.

3: The combined T

SP

 and V

HYS

 =specifications are due to new Schmitt trigger inputs which provide improved 

noise and spike suppression.  This eliminates the need for a T

I

 specification for standard operation.

4: This parameter is not tested but guaranteed by characterization. For endurance estimates in a specific appli-

cation, please consult the Total Endurance Model which can be obtained on our website.

SCL

SDA
IN

SDA
OUT

T

SU

:

STA

T

SP

T

AA

T

F

T

LOW

T

HIGH

T

HD

:

STA

T

HD

:

DAT

T

SU

:

DAT

T

SU

:

STO

T

BUF

T

AA

T

R

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24AA164

DS21100G-page  4

 2004 Microchip Technology Inc.

2.0

FUNCTIONAL DESCRIPTION

The 24AA164 supports aBi-directional two wire bus
and data transmission protocol.  A device that sends
data onto the bus is defined as transmitter, and a
device receiving data as receiver.  The bus has to be
controlled by a master device which generates the
serial clock (SCL), controls the bus access, and gener-
ates the START and STOP conditions, while the
24AA164 works as slave.  Both, master and slave can
operate as transmitter or receiver but the master device
determines which mode is activated.

3.0

BUS CHARACTERISTICS

The following bus protocol has been defined:

• Data transfer may be initiated only when the bus 

is not busy.

• During data transfer, the data line must remain 

stable whenever the clock line is HIGH.  Changes 
in the data line while the clock line is HIGH will be 
interpreted as a START or STOP condition.

Accordingly, the following bus conditions have been
defined (Figure 3-1).

3.1

Bus not Busy (A)

Both data and clock lines remain HIGH.

3.2

Start Data Transfer (B)

A HIGH to LOW transition of the SDA line while the
clock (SCL) is HIGH determines a START condition.  All
commands must be preceded by a START condition.

3.3

Stop Data Transfer (C)

A LOW to HIGH transition of the SDA line while the
clock (SCL) is HIGH determines a STOP condition.  All
operations must be ended with a STOP condition.

3.4

Data Valid (D)

The state of the data line represents valid data when,
after a START condition, the data line is stable for the
duration of the HIGH period of the clock signal.

The data on the line must be changed during the LOW
period of the clock signal.  There is one clock pulse per
bit of data.

Each data transfer is initiated with a START condition
and terminated with a STOP condition.  The number of
the data bytes transferred between the START and
STOP conditions is determined by the master device
and is theoretically unlimited, although only the last 16
will be stored when doing a write operation.  When an
overwrite does occur it will replace data in a first in first
out fashion.

3.5

Acknowledge

Each receiving device, when addressed, is obliged to
generate an acknowledge after the reception of each
byte. The master device must generate an extra clock
pulse which is associated with this acknowledge bit.

The device that acknowledges, has to pull down the
SDA line during the acknowledge clock pulse in such a
way that the SDA line is stable LOW during the HIGH
period of the acknowledge related clock pulse.   Of
course, setup and hold times must be taken into
account.  During  reads, a master must signal an end of
data to the slave by not generating an acknowledge bit
on the last byte that has been clocked out of the slave.
In this case, the slave (24AA164) will leave the data line
HIGH to enable the master to generate the STOP con-
dition.

Note:

The 24AA164 does not generate any
acknowledge bits if an internal program-
ming cycle is in progress.

FIGURE 3-1:

DATA TRANSFER SEQUENCE ON THE SERIAL BUS

SCL

SDA

(A)

(B)

(D)

(D)

(A)

(C)

START

CONDITION

ADDRESS OR

ACKNOWLEDGE

VALID

DATA

ALLOWED

TO CHANGE

STOP

CONDITION

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 2004 Microchip Technology Inc.

DS21100G-page  5

24AA164

3.6

Device Addressing

A control byte is the first byte received following the
start condition from the master device.  The first bit is
always a one.  The next three bits of the control byte
are the device select bits (A2, A1, A0).  They are used
to select which of the eight devices are to be accessed.
The A1 bit must be the inverse of the A1 device select
pin.  

The next three bits of the control byte are the block
select bits (B2, B1, B0).  They are used by the master
device to select which of the eight 256 word blocks of
memory are to be accessed.  These bits are in effect
the three most significant bits of the word address.  

The last bit of the control byte defines the operation to
be performed.  When set to one a read operation is
selected, when set to zero a write operation is selected.
Following the start condition, the 24AA164 looks for the
slave address for the device selected.  Depending on
the state of the R/W bit, the 24AA164 will select a read
or write operation. 

FIGURE 3-2:

CONTROL BYTE 
ALLOCATION

Operation

Control Code

Block Select

R/W

Read

1

A2 A1 A0

Block Address

1

Write

1

A2 A1 A0

Block Address

0

SLAVE ADDRESS

1

A2

A1

A0

B2

B1

B0

R/W A

START

READ/WRITE

MSB

LSB

4.0

WRITE OPERATION

4.1

Byte Write

Following the start condition from the master, the
device code (4 bits), the block address (3 bits), and the
R/W bit which is a logic low is placed onto the bus by
the master transmitter.  This indicates to the addressed
slave receiver that a byte with a word address will fol-
low after it has generated an acknowledge bit during
the ninth clock cycle.  Therefore the next byte transmit-
ted by the master is the word address and will be writ-
ten into the address pointer of the 24AA164.  After
receiving another acknowledge signal from the
24AA164 the master device will transmit the data word
to be written into the addressed memory location.  The
24AA164 acknowledges again and the master gener-
ates a stop condition.  This initiates the internal write
cycle, and during this time the 24AA164 will not gener-
ate acknowledge signals (Figure 4-1).

4.2

Page Write 

The write control byte, word address and the first data
byte are transmitted to the 24AA164 in the same way
as in a byte write.  But instead of generating a stop con-
dition the master transmits up to 16 data bytes to the
24AA164 which are temporarily stored in the on-chip
page buffer and will be written into the memory after the
master has transmitted a stop condition.  After the
receipt of each word, the four lower order address
pointer bits are internally incremented by one.  The
higher order seven bits of the word address remains
constant.  If the master should transmit more than 16
words prior to generating the stop condition, the
address counter will roll over and the previously
received data will be overwritten.  As with the byte write
operation, once the stop condition is received an inter-
nal write cycle will begin (Figure 4-2).

Note:

Page write operations are limited to writing
bytes within a single physical page,
regardless of the number of bytes actually
being written. Physical page boundaries
start at addresses that are integer multiples
of the page buffer size (or ‘page size’) and
end at addresses that are integer multiples
of [page size - 1]. If a page write command
attempts to write across a physical page
boundary, the result is that the data wraps
around to the beginning of the current page
(overwriting data previously stored there),
instead of being written to the next page as
might be expected. It is therefore neces-
sary for the application software to prevent
page write operations that would attempt to
cross a page boundary.

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24AA164

DS21100G-page  6

 2004 Microchip Technology Inc.

FIGURE 4-1:

BYTE WRITE

FIGURE 4-2:

PAGE WRITE

S
T
O
P

SDA LINE

P

DATA

S

T

A

R

T

CONTROL

BYTE

S

WORD

ADDRESS

BUS ACTIVITY:
MASTER

BUS ACTIVITY:

A

C

K

A

C

K

A

C

K

1 A2

B0

A1 A0 B2 B1

S
T
O
P

SDA LINE

P

DATA n

S

T

A
R

T

CONTROL

BYTE

WORD

ADDRESS (n)

BUS ACTIVITY:
MASTER

BUS ACTIVITY:

A
C
K

A
C
K

A
C
K

DATA n + 1

A
C
K

DATA n + 15

A
C
K

S

A2

B0

A1 A0 B2 B1

5.0

ACKNOWLEDGE POLLING

Since the device will not acknowledge during a write
cycle, this can be used to determine when the cycle is
complete (this feature can be used to maximize bus
throughput).  Once the stop condition for a write com-
mand has been issued from the master, the device ini-
tiates the internally timed write cycle.  ACK polling can
be initiated immediately.  This involves the master
sending a start condition followed by the control byte for
a write command (R/W = 0).  If the device is still busy
with the write cycle, then no ACK will be returned.  If the
cycle is complete, then the device will return the ACK
and the master can then proceed with the next read or
write command.  See Figure 5-1 for flow diagram.

FIGURE 5-1:

ACKNOWLEDGE POLLING 
FLOW

6.0

WRITE PROTECTION

The 24AA164 can be used as a serial ROM when the
WP pin is connected to V

CC

.  Programming will be

inhibited and the entire memory will be write-protected.

Send

Write Command

Send Stop

Condition to

Initiate Write Cycle

Send Start

Send Control Byte

with R/W = 0

Did Device

Acknowledge

(ACK = 0)?

Next

Operation

NO

YES

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 2004 Microchip Technology Inc.

DS21100G-page  7

24AA164

7.0

READ OPERATION

Read operations are initiated in the same way as write
operations with the exception that the R/W bit of the slave
address is set to one.  There are three basic types of read
operations: current address  read, random read, and
sequential read.

7.1

Current Address Read

The 24AA164 contains an address counter that maintains
the address of the last word accessed, internally incre-
mented by one. Therefore, if the previous access  (either a
read or write operation) was to address n, the next current
address read operation would access data from address n
+ 1. Upon receipt of the slave address with R/W bit set to
one, the 24AA164 issues an acknowledge and transmits
the 8-bit data word. The master will not acknowledge the
transfer but does generate a stop condition and the
24AA164 discontinues transmission (Figure 7-1).

7.2

Random Read

Random read operations allow the master to access any
memory location in a random manner.  To perform this
type of read operation, first the word address must be set.
This is done by sending the word address to the 24AA164
as part of a write operation.  After the word address is sent,
the master generates a start condition following the
acknowledge.  This terminates the write operation, but not
before the internal address pointer is set.  Then the master
issues the control byte again but with the R/W bit set to a
one. The 24AA164 will then issue an acknowledge and
transmits the 8-bit data word.  The master will not acknowl-
edge the transfer but does generate a stop condition and
the 24AA164 discontinues transmission (Figure 7-2).

7.3

Sequential Read

Sequential reads are initiated in the same way as a ran-
dom read except that after the 24AA164 transmits the
first data byte, the master issues an acknowledge as
opposed to a stop condition in a random read.  This
directs the 24AA164 to transmit the next sequentially
addressed 8-bit word (Figure 7-3).

To provide sequential reads the 24AA164 contains an
internal address pointer which is incremented by one at
the completion of each operation.  This address pointer
allows an entire device memory contents to be serially
read during one operation.  

7.4

Noise Protection

The 24AA164 employs a V

CC

 threshold detector circuit

which disables the internal erase/write logic if the V

CC

is below 1.5 volts at nominal conditions.

The SCL and SDA inputs have Schmitt trigger and filter
circuits which suppress noise spikes to assure proper
device operation even on a noisy bus.

FIGURE 7-1:

CURRENT ADDRESS READ

FIGURE 7-2:

RANDOM READ

FIGURE 7-3:

SEQUENTIAL READ

CONTROL

A

C

K

S

T

A

R

T

BYTE

DATA n

 ACTIVITY

TER

 LINE

 ACTIVITY

S

1 A2 A1 A0 B2 B1 B0

S

CONTROL

BYTE

A

C

K

WORD

ADDRESS (n)

CONTROL

BYTE

S
T
A
R
T

A

C
K

2 A1A0B2B1B0

L

A
C
K

DATA n

DATA n + 1

DATA n + 2

A
C
K

A
C
K

A
C
K

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24AA164

DS21100G-page  8

 2004 Microchip Technology Inc.

8.0

PIN DESCRIPTIONS

8.1

SDA Serial Address/Data Input/Output

This is a Bi-directional pin used to transfer addresses
and data into and data out of the device.  It is an open
drain terminal, therefore the SDA bus requires a pullup
resistor to V

CC

 (typical 10K

 for 100 kHz, 2 K

 for

400 kHz).

For normal data transfer SDA is allowed to change only
during SCL low.  Changes during SCL high are
reserved for indicating the START and STOP condi-
tions.

8.2

SCL Serial Clock 

This input is used to synchronize the data transfer from
and to the device.

8.3

WP

This pin must be connected to either V

SS

 or V

CC

.

If tied to V

SS

, normal memory operation is enabled

(read/write the entire memory 000-7FF).

If tied to V

CC

, WRITE operations are inhibited.  The

entire memory will be write-protected.  Read operations
are not affected.

This feature allows the user to use the 24AA164 as a
serial ROM when WP is enabled (tied to V

CC

).

8.4

A0, A1, A2

These pins are used to configure the proper chip
address in multiple-chip applications (more than one
24AA164 on the same bus).  The levels on these pins
are compared to the corresponding bits in the slave
address. The chip is selected if the compare is true.  

Up to eight 24AA164s may be connected to the same
bus.  These pins must be connected to either V

SS

 or

V

CC

.

Note:

The level on A1 is compared to the inverse
of the slave address.

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24AA164

24AA164 Product Identification System

To order or to obtain information (e.g., on pricing or delivery), please use the listed part numbers, and refer to the factory or the listed
sales offices.  

Sales and Support

Data Sheets
Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recom-
mended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:
1.

Your local Microchip sales office

2.

The Microchip Corporate Literature Center U.S. FAX: (602) 786-7277

3.

The Microchip Worldwide Site (www.microchip.com)

Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using.

New Customer Notification System
Register on our web site (www.microchip.com/cn) to receive the most current information on our products.

Package:

P = Plastic DIP (300 mil Body), 8-lead

SN = Plastic SOIC (150 mil Body), 8-lead

Temperature 

Blank = 0

°

C to 70

°

Range:

Device:

24AA164

16K I

2

C Serial EEPROM

24AA164T

16K I

2

C Serial EEPROM (Tape and Reel)

24AA164

/P

 2004 Microchip Technology Inc.

DS21100G-page  9

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24AA164

DS21100G-page  10

 2004 Microchip Technology Inc.

NOTES:

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 2004 Microchip Technology Inc.

DS21100G-page  1

FEATURES

• Single supply with operation down to 1.8V
• Low power CMOS technology

- 1 mA active current typical
- 10 

µ

A standby current typical at 5.5V

- 5 

µ

A standby current typical at 3.0V

• Organized as 8 blocks of 256 bytes (8 x 256 x 8)
• 2-wire serial interface bus, I

2

C

 compatible

• Functional address inputs for cascading up to 8 

devices

• Schmitt trigger, filtered inputs for noise suppres-

sion

• Output slope control to eliminate ground bounce
• 100 kHz (1.8V) and 400 kHz (5V) compatibility
• Self-timed write cycle (including auto-erase)
• Page-write buffer for up to 16 bytes
• 2 ms typical write cycle time for page-write
• Hardware write protect for entire memory
• Can be operated as a serial ROM
• Factory programming (QTP) available
• ESD protection > 4,000V
• 1,000,000 Erase/Write cycles guaranteed
• Data retention > 200 years
• 8-pin DIP, 8-lead SOIC packages
• Available for commercial temperature range

DESCRIPTION

The Microchip Technology Inc. 24AA164 is a cascad-
able 16K bit Electrically Erasable PROM.  The device
is organized as eight blocks of 256 x 8-bit memory with
a 2-wire serial interface. Low voltage design permits
operation down to 1.8 volts (end-of-life voltage for most
popular battery technologies) with standby and active
currents of only 5 

µ

A and 1 mA respectively. The

24AA164 also has a page-write capability for up to 16
bytes of data. The 24AA164 is available in the standard
8-pin DIP and 8-lead surface mount SOIC packages.

The three select pins, A0, A1, and A2, function as chip
select inputs and allow up to eight devices to share a
common bus, for up to 128K bits total system
EEPROM.

- Commercial (C):

0°C to +70°C

PACKAGE TYPES

BLOCK DIAGRAM

24
A

A

1

6

4

A0

A1

A2

V

SS

1

2

3

4

8

7

6

5

V

CC

WP

SCL

SDA

24A

A164

A0

A1

A2

V

SS

1

2

3

4

8

7

6

5

V

CC

WP

SCL

SDA

PDIP

8-lead
SOIC

HV GENERATOR

EEPROM ARRAY 

(8 x 256 x 8)

PAGE LATCHES

YDEC

XDEC

SENSE AMP 

R/W CONTROL

MEMORY 

CONTROL 

LOGIC

I/O 

CONTROL 

LOGIC

WP

SDA

SCL

V

CC

V

SS

A0

A2

A1

24AA164

16K 1.8V Cascadable I

2

C

 Serial EEPROM

I

2

C is a trademark of Philips Corporation.

Obsolete Device

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24AA164

DS21100G-page  2

 2004 Microchip Technology Inc.

1.0

ELECTRICAL CHARACTERISTICS

1.1

Maximum Ratings*

V

CC

...................................................................................7.0V

All inputs and outputs w.r.t. V

SS..................

-0.3V to V

CC

 +1.0V

Storage temperature .....................................-65°C to +150°C
Ambient temp. with power applied ................-65°C to +125°C
Soldering temperature of leads (10 seconds) ............. +300°C
ESD protection on all pins

..................................................≥

 4 kV

*Notice: Stresses above those listed under “Maximum ratings”
may cause permanent damage to the device.  This is a stress rat-
ing only and functional operation of the device at those or any
other conditions above those indicated in the operational listings
of this specification is not implied.  Exposure to maximum rating
conditions for extended periods may affect device reliability.

TABLE 1-1:

PIN FUNCTION TABLE

Name

Function

V

SS

Ground

SDA

Serial Address/Data I/O

SCL

Serial Clock

WP

Write Protect Input

V

CC

1.8V to 6.0V Power Supply

A0, A1, A2

Chip Address Inputs

TABLE 1-2:

DC CHARACTERISTICS

FIGURE 1-1:

BUS TIMING START/STOP

V

CC

 = 1.8V to +6.0

Commercial (C):  Tamb = 0°C to +70°C

Parameter

Symbol

Min

Typ

Max

Units

Conditions

WP, SCL and SDA pins:

High level input voltage

V

IH

.7 V

CC

V

Low level input voltage

V

IL

.3  V

CC

V

Hysteresis of Schmitt trigger inputs

V

HYS

.05 V

CC

V

(Note) 

Low level output voltage

V

OL

.40

V

I

OL 

= 3.0 mA, V

CC 

= 1.8V

Input leakage current

I

LI

-10

10

µ

A

V

IN 

= .1V to V

CC

Output leakage current

I

LO

-10

10

µ

A

V

OUT 

= .1V to V

CC

Pin capacitance 
(all inputs/outputs

C

IN

C

OUT

10

pF

V

CC

 

= 5.0V (Note 1)

Tamb = 25°C, F

CLK 

= 1 MHz

Operating current

I

CC

 

Write

I

CC

 

Read




0.5

0.05

3

1

mA
mA
mA
mA

V

CC

 

= 5.5V, SCL = 400 kHz

V

CC

 

= 1.8V, SCL = 100 kHz

V

CC

 

= 5.5V, SCL = 400 kHz

V

CC

 

= 1.8V, SCL = 100 kHz

Standby current

I

CCS




3

100

30

µ

A

µ

A

µ

A

V

CC

 

= 5.5V, SDA = SCL=V

CC

V

CC

 

= 3.0V, SDA = SCL=V

CC

V

CC

 

= 1.8V, SDA = SCL=V

CC

WP = V

SS

Note:

 This parameter is periodically sampled and not 100% tested.

T

SU

:

STA

T

HD

:

STA

V

HYS

T

SU

:

STO

START

STOP

SCL

SDA

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 2004 Microchip Technology Inc.

DS21100G-page  3

24AA164

TABLE 1-3:

AC CHARACTERISTICS

FIGURE 1-2:

BUS TIMING DATA

Parameter

Symbol

STANDARD

MODE

V

CC

 

= 4.5-5.5V

FAST MODE

Units

Remarks

Min

Max

Min

Max

Clock frequency

F

CLK

100

400

kHz

Clock high time

T

HIGH

4000

600

ns

Clock low time

T

LOW

4700

1300

ns

SDA and SCL rise time

T

R

1000

300

ns

(Note 1)

SDA and SCL fall time

T

F

300

300

ns

(Note 1)

START condition hold 
time

T

HD

:

STA

4000

600

ns

After this period the first 
clock pulse is generated

START condition setup 
time

T

SU

:

STA

4700

600

ns

Only relevant for repeated 
START condition

Data input hold time

T

HD

:

DAT

0

0

ns

Data input setup time

T

SU

:

DAT

250

100

ns

STOP condition setup 
time

T

SU

:

STO

4000

600

ns

Output valid from clock

T

AA

3500

900

ns

(Note 2)

Bus free time

T

BUF

4700

1300

ns

Time the bus must be free 
before a new transmission 
can start 

Output fall time from V

IH

 

min to V

IL

 max

T

OF

250

20 + 0.1 

C

B

250

ns

(Note 1), C

B

 

 100 pF

Input filter spike suppres-
sion (SDA and SCL pins)

T

SP

50

50

ns

(Note 3)

Write cycle time

T

WR

10

10

ms

Byte or Page mode

Endurance

1M

1M

cycles

25°C, Vcc = 5.0V, Block 
Mode ((Note 4)

Note 1: Not 100% tested.  C

B

 = total capacitance of one bus line in pF.

2: As a transmitter, the device must provide an internal minimum delay time to bridge the undefined region 

(minimum 300 ns) of the falling edge of SCL to avoid unintended generation of START or STOP conditions.

3: The combined T

SP

 and V

HYS

 =specifications are due to new Schmitt trigger inputs which provide improved 

noise and spike suppression.  This eliminates the need for a T

I

 specification for standard operation.

4: This parameter is not tested but guaranteed by characterization. For endurance estimates in a specific appli-

cation, please consult the Total Endurance Model which can be obtained on our website.

SCL

SDA
IN

SDA
OUT

T

SU

:

STA

T

SP

T

AA

T

F

T

LOW

T

HIGH

T

HD

:

STA

T

HD

:

DAT

T

SU

:

DAT

T

SU

:

STO

T

BUF

T

AA

T

R

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24AA164

DS21100G-page  4

 2004 Microchip Technology Inc.

2.0

FUNCTIONAL DESCRIPTION

The 24AA164 supports aBi-directional two wire bus
and data transmission protocol.  A device that sends
data onto the bus is defined as transmitter, and a
device receiving data as receiver.  The bus has to be
controlled by a master device which generates the
serial clock (SCL), controls the bus access, and gener-
ates the START and STOP conditions, while the
24AA164 works as slave.  Both, master and slave can
operate as transmitter or receiver but the master device
determines which mode is activated.

3.0

BUS CHARACTERISTICS

The following bus protocol has been defined:

• Data transfer may be initiated only when the bus 

is not busy.

• During data transfer, the data line must remain 

stable whenever the clock line is HIGH.  Changes 
in the data line while the clock line is HIGH will be 
interpreted as a START or STOP condition.

Accordingly, the following bus conditions have been
defined (Figure 3-1).

3.1

Bus not Busy (A)

Both data and clock lines remain HIGH.

3.2

Start Data Transfer (B)

A HIGH to LOW transition of the SDA line while the
clock (SCL) is HIGH determines a START condition.  All
commands must be preceded by a START condition.

3.3

Stop Data Transfer (C)

A LOW to HIGH transition of the SDA line while the
clock (SCL) is HIGH determines a STOP condition.  All
operations must be ended with a STOP condition.

3.4

Data Valid (D)

The state of the data line represents valid data when,
after a START condition, the data line is stable for the
duration of the HIGH period of the clock signal.

The data on the line must be changed during the LOW
period of the clock signal.  There is one clock pulse per
bit of data.

Each data transfer is initiated with a START condition
and terminated with a STOP condition.  The number of
the data bytes transferred between the START and
STOP conditions is determined by the master device
and is theoretically unlimited, although only the last 16
will be stored when doing a write operation.  When an
overwrite does occur it will replace data in a first in first
out fashion.

3.5

Acknowledge

Each receiving device, when addressed, is obliged to
generate an acknowledge after the reception of each
byte. The master device must generate an extra clock
pulse which is associated with this acknowledge bit.

The device that acknowledges, has to pull down the
SDA line during the acknowledge clock pulse in such a
way that the SDA line is stable LOW during the HIGH
period of the acknowledge related clock pulse.   Of
course, setup and hold times must be taken into
account.  During  reads, a master must signal an end of
data to the slave by not generating an acknowledge bit
on the last byte that has been clocked out of the slave.
In this case, the slave (24AA164) will leave the data line
HIGH to enable the master to generate the STOP con-
dition.

Note:

The 24AA164 does not generate any
acknowledge bits if an internal program-
ming cycle is in progress.

FIGURE 3-1:

DATA TRANSFER SEQUENCE ON THE SERIAL BUS

SCL

SDA

(A)

(B)

(D)

(D)

(A)

(C)

START

CONDITION

ADDRESS OR

ACKNOWLEDGE

VALID

DATA

ALLOWED

TO CHANGE

STOP

CONDITION

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 2004 Microchip Technology Inc.

DS21100G-page  5

24AA164

3.6

Device Addressing

A control byte is the first byte received following the
start condition from the master device.  The first bit is
always a one.  The next three bits of the control byte
are the device select bits (A2, A1, A0).  They are used
to select which of the eight devices are to be accessed.
The A1 bit must be the inverse of the A1 device select
pin.  

The next three bits of the control byte are the block
select bits (B2, B1, B0).  They are used by the master
device to select which of the eight 256 word blocks of
memory are to be accessed.  These bits are in effect
the three most significant bits of the word address.  

The last bit of the control byte defines the operation to
be performed.  When set to one a read operation is
selected, when set to zero a write operation is selected.
Following the start condition, the 24AA164 looks for the
slave address for the device selected.  Depending on
the state of the R/W bit, the 24AA164 will select a read
or write operation. 

FIGURE 3-2:

CONTROL BYTE 
ALLOCATION

Operation

Control Code

Block Select

R/W

Read

1

A2 A1 A0

Block Address

1

Write

1

A2 A1 A0

Block Address

0

SLAVE ADDRESS

1

A2

A1

A0

B2

B1

B0

R/W A

START

READ/WRITE

MSB

LSB

4.0

WRITE OPERATION

4.1

Byte Write

Following the start condition from the master, the
device code (4 bits), the block address (3 bits), and the
R/W bit which is a logic low is placed onto the bus by
the master transmitter.  This indicates to the addressed
slave receiver that a byte with a word address will fol-
low after it has generated an acknowledge bit during
the ninth clock cycle.  Therefore the next byte transmit-
ted by the master is the word address and will be writ-
ten into the address pointer of the 24AA164.  After
receiving another acknowledge signal from the
24AA164 the master device will transmit the data word
to be written into the addressed memory location.  The
24AA164 acknowledges again and the master gener-
ates a stop condition.  This initiates the internal write
cycle, and during this time the 24AA164 will not gener-
ate acknowledge signals (Figure 4-1).

4.2

Page Write 

The write control byte, word address and the first data
byte are transmitted to the 24AA164 in the same way
as in a byte write.  But instead of generating a stop con-
dition the master transmits up to 16 data bytes to the
24AA164 which are temporarily stored in the on-chip
page buffer and will be written into the memory after the
master has transmitted a stop condition.  After the
receipt of each word, the four lower order address
pointer bits are internally incremented by one.  The
higher order seven bits of the word address remains
constant.  If the master should transmit more than 16
words prior to generating the stop condition, the
address counter will roll over and the previously
received data will be overwritten.  As with the byte write
operation, once the stop condition is received an inter-
nal write cycle will begin (Figure 4-2).

Note:

Page write operations are limited to writing
bytes within a single physical page,
regardless of the number of bytes actually
being written. Physical page boundaries
start at addresses that are integer multiples
of the page buffer size (or ‘page size’) and
end at addresses that are integer multiples
of [page size - 1]. If a page write command
attempts to write across a physical page
boundary, the result is that the data wraps
around to the beginning of the current page
(overwriting data previously stored there),
instead of being written to the next page as
might be expected. It is therefore neces-
sary for the application software to prevent
page write operations that would attempt to
cross a page boundary.

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24AA164

DS21100G-page  6

 2004 Microchip Technology Inc.

FIGURE 4-1:

BYTE WRITE

FIGURE 4-2:

PAGE WRITE

S
T
O
P

SDA LINE

P

DATA

S

T

A

R

T

CONTROL

BYTE

S

WORD

ADDRESS

BUS ACTIVITY:
MASTER

BUS ACTIVITY:

A

C

K

A

C

K

A

C

K

1 A2

B0

A1 A0 B2 B1

S
T
O
P

SDA LINE

P

DATA n

S

T

A
R

T

CONTROL

BYTE

WORD

ADDRESS (n)

BUS ACTIVITY:
MASTER

BUS ACTIVITY:

A
C
K

A
C
K

A
C
K

DATA n + 1

A
C
K

DATA n + 15

A
C
K

S

A2

B0

A1 A0 B2 B1

5.0

ACKNOWLEDGE POLLING

Since the device will not acknowledge during a write
cycle, this can be used to determine when the cycle is
complete (this feature can be used to maximize bus
throughput).  Once the stop condition for a write com-
mand has been issued from the master, the device ini-
tiates the internally timed write cycle.  ACK polling can
be initiated immediately.  This involves the master
sending a start condition followed by the control byte for
a write command (R/W = 0).  If the device is still busy
with the write cycle, then no ACK will be returned.  If the
cycle is complete, then the device will return the ACK
and the master can then proceed with the next read or
write command.  See Figure 5-1 for flow diagram.

FIGURE 5-1:

ACKNOWLEDGE POLLING 
FLOW

6.0

WRITE PROTECTION

The 24AA164 can be used as a serial ROM when the
WP pin is connected to V

CC

.  Programming will be

inhibited and the entire memory will be write-protected.

Send

Write Command

Send Stop

Condition to

Initiate Write Cycle

Send Start

Send Control Byte

with R/W = 0

Did Device

Acknowledge

(ACK = 0)?

Next

Operation

NO

YES

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 2004 Microchip Technology Inc.

DS21100G-page  7

24AA164

7.0

READ OPERATION

Read operations are initiated in the same way as write
operations with the exception that the R/W bit of the slave
address is set to one.  There are three basic types of read
operations: current address  read, random read, and
sequential read.

7.1

Current Address Read

The 24AA164 contains an address counter that maintains
the address of the last word accessed, internally incre-
mented by one. Therefore, if the previous access  (either a
read or write operation) was to address n, the next current
address read operation would access data from address n
+ 1. Upon receipt of the slave address with R/W bit set to
one, the 24AA164 issues an acknowledge and transmits
the 8-bit data word. The master will not acknowledge the
transfer but does generate a stop condition and the
24AA164 discontinues transmission (Figure 7-1).

7.2

Random Read

Random read operations allow the master to access any
memory location in a random manner.  To perform this
type of read operation, first the word address must be set.
This is done by sending the word address to the 24AA164
as part of a write operation.  After the word address is sent,
the master generates a start condition following the
acknowledge.  This terminates the write operation, but not
before the internal address pointer is set.  Then the master
issues the control byte again but with the R/W bit set to a
one. The 24AA164 will then issue an acknowledge and
transmits the 8-bit data word.  The master will not acknowl-
edge the transfer but does generate a stop condition and
the 24AA164 discontinues transmission (Figure 7-2).

7.3

Sequential Read

Sequential reads are initiated in the same way as a ran-
dom read except that after the 24AA164 transmits the
first data byte, the master issues an acknowledge as
opposed to a stop condition in a random read.  This
directs the 24AA164 to transmit the next sequentially
addressed 8-bit word (Figure 7-3).

To provide sequential reads the 24AA164 contains an
internal address pointer which is incremented by one at
the completion of each operation.  This address pointer
allows an entire device memory contents to be serially
read during one operation.  

7.4

Noise Protection

The 24AA164 employs a V

CC

 threshold detector circuit

which disables the internal erase/write logic if the V

CC

is below 1.5 volts at nominal conditions.

The SCL and SDA inputs have Schmitt trigger and filter
circuits which suppress noise spikes to assure proper
device operation even on a noisy bus.

FIGURE 7-1:

CURRENT ADDRESS READ

FIGURE 7-2:

RANDOM READ

FIGURE 7-3:

SEQUENTIAL READ

CONTROL

A

C

K

S

T

A

R

T

BYTE

DATA n

 ACTIVITY

TER

 LINE

 ACTIVITY

S

1 A2 A1 A0 B2 B1 B0

S

CONTROL

BYTE

A

C

K

WORD

ADDRESS (n)

CONTROL

BYTE

S
T
A
R
T

A

C
K

2 A1A0B2B1B0

L

A
C
K

DATA n

DATA n + 1

DATA n + 2

A
C
K

A
C
K

A
C
K

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24AA164

DS21100G-page  8

 2004 Microchip Technology Inc.

8.0

PIN DESCRIPTIONS

8.1

SDA Serial Address/Data Input/Output

This is a Bi-directional pin used to transfer addresses
and data into and data out of the device.  It is an open
drain terminal, therefore the SDA bus requires a pullup
resistor to V

CC

 (typical 10K

 for 100 kHz, 2 K

 for

400 kHz).

For normal data transfer SDA is allowed to change only
during SCL low.  Changes during SCL high are
reserved for indicating the START and STOP condi-
tions.

8.2

SCL Serial Clock 

This input is used to synchronize the data transfer from
and to the device.

8.3

WP

This pin must be connected to either V

SS

 or V

CC

.

If tied to V

SS

, normal memory operation is enabled

(read/write the entire memory 000-7FF).

If tied to V

CC

, WRITE operations are inhibited.  The

entire memory will be write-protected.  Read operations
are not affected.

This feature allows the user to use the 24AA164 as a
serial ROM when WP is enabled (tied to V

CC

).

8.4

A0, A1, A2

These pins are used to configure the proper chip
address in multiple-chip applications (more than one
24AA164 on the same bus).  The levels on these pins
are compared to the corresponding bits in the slave
address. The chip is selected if the compare is true.  

Up to eight 24AA164s may be connected to the same
bus.  These pins must be connected to either V

SS

 or

V

CC

.

Note:

The level on A1 is compared to the inverse
of the slave address.

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24AA164

24AA164 Product Identification System

To order or to obtain information (e.g., on pricing or delivery), please use the listed part numbers, and refer to the factory or the listed
sales offices.  

Sales and Support

Data Sheets
Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recom-
mended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:
1.

Your local Microchip sales office

2.

The Microchip Corporate Literature Center U.S. FAX: (602) 786-7277

3.

The Microchip Worldwide Site (www.microchip.com)

Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using.

New Customer Notification System
Register on our web site (www.microchip.com/cn) to receive the most current information on our products.

Package:

P = Plastic DIP (300 mil Body), 8-lead

SN = Plastic SOIC (150 mil Body), 8-lead

Temperature 

Blank = 0

°

C to 70

°

Range:

Device:

24AA164

16K I

2

C Serial EEPROM

24AA164T

16K I

2

C Serial EEPROM (Tape and Reel)

24AA164

/P

 2004 Microchip Technology Inc.

DS21100G-page  9

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24AA164

DS21100G-page  10

 2004 Microchip Technology Inc.

NOTES:

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 2004 Microchip Technology Inc.

DS21100G-page  1

FEATURES

• Single supply with operation down to 1.8V
• Low power CMOS technology

- 1 mA active current typical
- 10 

µ

A standby current typical at 5.5V

- 5 

µ

A standby current typical at 3.0V

• Organized as 8 blocks of 256 bytes (8 x 256 x 8)
• 2-wire serial interface bus, I

2

C

 compatible

• Functional address inputs for cascading up to 8 

devices

• Schmitt trigger, filtered inputs for noise suppres-

sion

• Output slope control to eliminate ground bounce
• 100 kHz (1.8V) and 400 kHz (5V) compatibility
• Self-timed write cycle (including auto-erase)
• Page-write buffer for up to 16 bytes
• 2 ms typical write cycle time for page-write
• Hardware write protect for entire memory
• Can be operated as a serial ROM
• Factory programming (QTP) available
• ESD protection > 4,000V
• 1,000,000 Erase/Write cycles guaranteed
• Data retention > 200 years
• 8-pin DIP, 8-lead SOIC packages
• Available for commercial temperature range

DESCRIPTION

The Microchip Technology Inc. 24AA164 is a cascad-
able 16K bit Electrically Erasable PROM.  The device
is organized as eight blocks of 256 x 8-bit memory with
a 2-wire serial interface. Low voltage design permits
operation down to 1.8 volts (end-of-life voltage for most
popular battery technologies) with standby and active
currents of only 5 

µ

A and 1 mA respectively. The

24AA164 also has a page-write capability for up to 16
bytes of data. The 24AA164 is available in the standard
8-pin DIP and 8-lead surface mount SOIC packages.

The three select pins, A0, A1, and A2, function as chip
select inputs and allow up to eight devices to share a
common bus, for up to 128K bits total system
EEPROM.

- Commercial (C):

0°C to +70°C

PACKAGE TYPES

BLOCK DIAGRAM

24
A

A

1

6

4

A0

A1

A2

V

SS

1

2

3

4

8

7

6

5

V

CC

WP

SCL

SDA

24A

A164

A0

A1

A2

V

SS

1

2

3

4

8

7

6

5

V

CC

WP

SCL

SDA

PDIP

8-lead
SOIC

HV GENERATOR

EEPROM ARRAY 

(8 x 256 x 8)

PAGE LATCHES

YDEC

XDEC

SENSE AMP 

R/W CONTROL

MEMORY 

CONTROL 

LOGIC

I/O 

CONTROL 

LOGIC

WP

SDA

SCL

V

CC

V

SS

A0

A2

A1

24AA164

16K 1.8V Cascadable I

2

C

 Serial EEPROM

I

2

C is a trademark of Philips Corporation.

Obsolete Device

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24AA164

DS21100G-page  2

 2004 Microchip Technology Inc.

1.0

ELECTRICAL CHARACTERISTICS

1.1

Maximum Ratings*

V

CC

...................................................................................7.0V

All inputs and outputs w.r.t. V

SS..................

-0.3V to V

CC

 +1.0V

Storage temperature .....................................-65°C to +150°C
Ambient temp. with power applied ................-65°C to +125°C
Soldering temperature of leads (10 seconds) ............. +300°C
ESD protection on all pins

..................................................≥

 4 kV

*Notice: Stresses above those listed under “Maximum ratings”
may cause permanent damage to the device.  This is a stress rat-
ing only and functional operation of the device at those or any
other conditions above those indicated in the operational listings
of this specification is not implied.  Exposure to maximum rating
conditions for extended periods may affect device reliability.

TABLE 1-1:

PIN FUNCTION TABLE

Name

Function

V

SS

Ground

SDA

Serial Address/Data I/O

SCL

Serial Clock

WP

Write Protect Input

V

CC

1.8V to 6.0V Power Supply

A0, A1, A2

Chip Address Inputs

TABLE 1-2:

DC CHARACTERISTICS

FIGURE 1-1:

BUS TIMING START/STOP

V

CC

 = 1.8V to +6.0

Commercial (C):  Tamb = 0°C to +70°C

Parameter

Symbol

Min

Typ

Max

Units

Conditions

WP, SCL and SDA pins:

High level input voltage

V

IH

.7 V

CC

V

Low level input voltage

V

IL

.3  V

CC

V

Hysteresis of Schmitt trigger inputs

V

HYS

.05 V

CC

V

(Note) 

Low level output voltage

V

OL

.40

V

I

OL 

= 3.0 mA, V

CC 

= 1.8V

Input leakage current

I

LI

-10

10

µ

A

V

IN 

= .1V to V

CC

Output leakage current

I

LO

-10

10

µ

A

V

OUT 

= .1V to V

CC

Pin capacitance 
(all inputs/outputs

C

IN

C

OUT

10

pF

V

CC

 

= 5.0V (Note 1)

Tamb = 25°C, F

CLK 

= 1 MHz

Operating current

I

CC

 

Write

I

CC

 

Read




0.5

0.05

3

1

mA
mA
mA
mA

V

CC

 

= 5.5V, SCL = 400 kHz

V

CC

 

= 1.8V, SCL = 100 kHz

V

CC

 

= 5.5V, SCL = 400 kHz

V

CC

 

= 1.8V, SCL = 100 kHz

Standby current

I

CCS




3

100

30

µ

A

µ

A

µ

A

V

CC

 

= 5.5V, SDA = SCL=V

CC

V

CC

 

= 3.0V, SDA = SCL=V

CC

V

CC

 

= 1.8V, SDA = SCL=V

CC

WP = V

SS

Note:

 This parameter is periodically sampled and not 100% tested.

T

SU

:

STA

T

HD

:

STA

V

HYS

T

SU

:

STO

START

STOP

SCL

SDA

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 2004 Microchip Technology Inc.

DS21100G-page  3

24AA164

TABLE 1-3:

AC CHARACTERISTICS

FIGURE 1-2:

BUS TIMING DATA

Parameter

Symbol

STANDARD

MODE

V

CC

 

= 4.5-5.5V

FAST MODE

Units

Remarks

Min

Max

Min

Max

Clock frequency

F

CLK

100

400

kHz

Clock high time

T

HIGH

4000

600

ns

Clock low time

T

LOW

4700

1300

ns

SDA and SCL rise time

T

R

1000

300

ns

(Note 1)

SDA and SCL fall time

T

F

300

300

ns

(Note 1)

START condition hold 
time

T

HD

:

STA

4000

600

ns

After this period the first 
clock pulse is generated

START condition setup 
time

T

SU

:

STA

4700

600

ns

Only relevant for repeated 
START condition

Data input hold time

T

HD

:

DAT

0

0

ns

Data input setup time

T

SU

:

DAT

250

100

ns

STOP condition setup 
time

T

SU

:

STO

4000

600

ns

Output valid from clock

T

AA

3500

900

ns

(Note 2)

Bus free time

T

BUF

4700

1300

ns

Time the bus must be free 
before a new transmission 
can start 

Output fall time from V

IH

 

min to V

IL

 max

T

OF

250

20 + 0.1 

C

B

250

ns

(Note 1), C

B

 

 100 pF

Input filter spike suppres-
sion (SDA and SCL pins)

T

SP

50

50

ns

(Note 3)

Write cycle time

T

WR

10

10

ms

Byte or Page mode

Endurance

1M

1M

cycles

25°C, Vcc = 5.0V, Block 
Mode ((Note 4)

Note 1: Not 100% tested.  C

B

 = total capacitance of one bus line in pF.

2: As a transmitter, the device must provide an internal minimum delay time to bridge the undefined region 

(minimum 300 ns) of the falling edge of SCL to avoid unintended generation of START or STOP conditions.

3: The combined T

SP

 and V

HYS

 =specifications are due to new Schmitt trigger inputs which provide improved 

noise and spike suppression.  This eliminates the need for a T

I

 specification for standard operation.

4: This parameter is not tested but guaranteed by characterization. For endurance estimates in a specific appli-

cation, please consult the Total Endurance Model which can be obtained on our website.

SCL

SDA
IN

SDA
OUT

T

SU

:

STA

T

SP

T

AA

T

F

T

LOW

T

HIGH

T

HD

:

STA

T

HD

:

DAT

T

SU

:

DAT

T

SU

:

STO

T

BUF

T

AA

T

R

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24AA164

DS21100G-page  4

 2004 Microchip Technology Inc.

2.0

FUNCTIONAL DESCRIPTION

The 24AA164 supports aBi-directional two wire bus
and data transmission protocol.  A device that sends
data onto the bus is defined as transmitter, and a
device receiving data as receiver.  The bus has to be
controlled by a master device which generates the
serial clock (SCL), controls the bus access, and gener-
ates the START and STOP conditions, while the
24AA164 works as slave.  Both, master and slave can
operate as transmitter or receiver but the master device
determines which mode is activated.

3.0

BUS CHARACTERISTICS

The following bus protocol has been defined:

• Data transfer may be initiated only when the bus 

is not busy.

• During data transfer, the data line must remain 

stable whenever the clock line is HIGH.  Changes 
in the data line while the clock line is HIGH will be 
interpreted as a START or STOP condition.

Accordingly, the following bus conditions have been
defined (Figure 3-1).

3.1

Bus not Busy (A)

Both data and clock lines remain HIGH.

3.2

Start Data Transfer (B)

A HIGH to LOW transition of the SDA line while the
clock (SCL) is HIGH determines a START condition.  All
commands must be preceded by a START condition.

3.3

Stop Data Transfer (C)

A LOW to HIGH transition of the SDA line while the
clock (SCL) is HIGH determines a STOP condition.  All
operations must be ended with a STOP condition.

3.4

Data Valid (D)

The state of the data line represents valid data when,
after a START condition, the data line is stable for the
duration of the HIGH period of the clock signal.

The data on the line must be changed during the LOW
period of the clock signal.  There is one clock pulse per
bit of data.

Each data transfer is initiated with a START condition
and terminated with a STOP condition.  The number of
the data bytes transferred between the START and
STOP conditions is determined by the master device
and is theoretically unlimited, although only the last 16
will be stored when doing a write operation.  When an
overwrite does occur it will replace data in a first in first
out fashion.

3.5

Acknowledge

Each receiving device, when addressed, is obliged to
generate an acknowledge after the reception of each
byte. The master device must generate an extra clock
pulse which is associated with this acknowledge bit.

The device that acknowledges, has to pull down the
SDA line during the acknowledge clock pulse in such a
way that the SDA line is stable LOW during the HIGH
period of the acknowledge related clock pulse.   Of
course, setup and hold times must be taken into
account.  During  reads, a master must signal an end of
data to the slave by not generating an acknowledge bit
on the last byte that has been clocked out of the slave.
In this case, the slave (24AA164) will leave the data line
HIGH to enable the master to generate the STOP con-
dition.

Note:

The 24AA164 does not generate any
acknowledge bits if an internal program-
ming cycle is in progress.

FIGURE 3-1:

DATA TRANSFER SEQUENCE ON THE SERIAL BUS

SCL

SDA

(A)

(B)

(D)

(D)

(A)

(C)

START

CONDITION

ADDRESS OR

ACKNOWLEDGE

VALID

DATA

ALLOWED

TO CHANGE

STOP

CONDITION

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 2004 Microchip Technology Inc.

DS21100G-page  5

24AA164

3.6

Device Addressing

A control byte is the first byte received following the
start condition from the master device.  The first bit is
always a one.  The next three bits of the control byte
are the device select bits (A2, A1, A0).  They are used
to select which of the eight devices are to be accessed.
The A1 bit must be the inverse of the A1 device select
pin.  

The next three bits of the control byte are the block
select bits (B2, B1, B0).  They are used by the master
device to select which of the eight 256 word blocks of
memory are to be accessed.  These bits are in effect
the three most significant bits of the word address.  

The last bit of the control byte defines the operation to
be performed.  When set to one a read operation is
selected, when set to zero a write operation is selected.
Following the start condition, the 24AA164 looks for the
slave address for the device selected.  Depending on
the state of the R/W bit, the 24AA164 will select a read
or write operation. 

FIGURE 3-2:

CONTROL BYTE 
ALLOCATION

Operation

Control Code

Block Select

R/W

Read

1

A2 A1 A0

Block Address

1

Write

1

A2 A1 A0

Block Address

0

SLAVE ADDRESS

1

A2

A1

A0

B2

B1

B0

R/W A

START

READ/WRITE

MSB

LSB

4.0

WRITE OPERATION

4.1

Byte Write

Following the start condition from the master, the
device code (4 bits), the block address (3 bits), and the
R/W bit which is a logic low is placed onto the bus by
the master transmitter.  This indicates to the addressed
slave receiver that a byte with a word address will fol-
low after it has generated an acknowledge bit during
the ninth clock cycle.  Therefore the next byte transmit-
ted by the master is the word address and will be writ-
ten into the address pointer of the 24AA164.  After
receiving another acknowledge signal from the
24AA164 the master device will transmit the data word
to be written into the addressed memory location.  The
24AA164 acknowledges again and the master gener-
ates a stop condition.  This initiates the internal write
cycle, and during this time the 24AA164 will not gener-
ate acknowledge signals (Figure 4-1).

4.2

Page Write 

The write control byte, word address and the first data
byte are transmitted to the 24AA164 in the same way
as in a byte write.  But instead of generating a stop con-
dition the master transmits up to 16 data bytes to the
24AA164 which are temporarily stored in the on-chip
page buffer and will be written into the memory after the
master has transmitted a stop condition.  After the
receipt of each word, the four lower order address
pointer bits are internally incremented by one.  The
higher order seven bits of the word address remains
constant.  If the master should transmit more than 16
words prior to generating the stop condition, the
address counter will roll over and the previously
received data will be overwritten.  As with the byte write
operation, once the stop condition is received an inter-
nal write cycle will begin (Figure 4-2).

Note:

Page write operations are limited to writing
bytes within a single physical page,
regardless of the number of bytes actually
being written. Physical page boundaries
start at addresses that are integer multiples
of the page buffer size (or ‘page size’) and
end at addresses that are integer multiples
of [page size - 1]. If a page write command
attempts to write across a physical page
boundary, the result is that the data wraps
around to the beginning of the current page
(overwriting data previously stored there),
instead of being written to the next page as
might be expected. It is therefore neces-
sary for the application software to prevent
page write operations that would attempt to
cross a page boundary.

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24AA164

DS21100G-page  6

 2004 Microchip Technology Inc.

FIGURE 4-1:

BYTE WRITE

FIGURE 4-2:

PAGE WRITE

S
T
O
P

SDA LINE

P

DATA

S

T

A

R

T

CONTROL

BYTE

S

WORD

ADDRESS

BUS ACTIVITY:
MASTER

BUS ACTIVITY:

A

C

K

A

C

K

A

C

K

1 A2

B0

A1 A0 B2 B1

S
T
O
P

SDA LINE

P

DATA n

S

T

A
R

T

CONTROL

BYTE

WORD

ADDRESS (n)

BUS ACTIVITY:
MASTER

BUS ACTIVITY:

A
C
K

A
C
K

A
C
K

DATA n + 1

A
C
K

DATA n + 15

A
C
K

S

A2

B0

A1 A0 B2 B1

5.0

ACKNOWLEDGE POLLING

Since the device will not acknowledge during a write
cycle, this can be used to determine when the cycle is
complete (this feature can be used to maximize bus
throughput).  Once the stop condition for a write com-
mand has been issued from the master, the device ini-
tiates the internally timed write cycle.  ACK polling can
be initiated immediately.  This involves the master
sending a start condition followed by the control byte for
a write command (R/W = 0).  If the device is still busy
with the write cycle, then no ACK will be returned.  If the
cycle is complete, then the device will return the ACK
and the master can then proceed with the next read or
write command.  See Figure 5-1 for flow diagram.

FIGURE 5-1:

ACKNOWLEDGE POLLING 
FLOW

6.0

WRITE PROTECTION

The 24AA164 can be used as a serial ROM when the
WP pin is connected to V

CC

.  Programming will be

inhibited and the entire memory will be write-protected.

Send

Write Command

Send Stop

Condition to

Initiate Write Cycle

Send Start

Send Control Byte

with R/W = 0

Did Device

Acknowledge

(ACK = 0)?

Next

Operation

NO

YES

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 2004 Microchip Technology Inc.

DS21100G-page  7

24AA164

7.0

READ OPERATION

Read operations are initiated in the same way as write
operations with the exception that the R/W bit of the slave
address is set to one.  There are three basic types of read
operations: current address  read, random read, and
sequential read.

7.1

Current Address Read

The 24AA164 contains an address counter that maintains
the address of the last word accessed, internally incre-
mented by one. Therefore, if the previous access  (either a
read or write operation) was to address n, the next current
address read operation would access data from address n
+ 1. Upon receipt of the slave address with R/W bit set to
one, the 24AA164 issues an acknowledge and transmits
the 8-bit data word. The master will not acknowledge the
transfer but does generate a stop condition and the
24AA164 discontinues transmission (Figure 7-1).

7.2

Random Read

Random read operations allow the master to access any
memory location in a random manner.  To perform this
type of read operation, first the word address must be set.
This is done by sending the word address to the 24AA164
as part of a write operation.  After the word address is sent,
the master generates a start condition following the
acknowledge.  This terminates the write operation, but not
before the internal address pointer is set.  Then the master
issues the control byte again but with the R/W bit set to a
one. The 24AA164 will then issue an acknowledge and
transmits the 8-bit data word.  The master will not acknowl-
edge the transfer but does generate a stop condition and
the 24AA164 discontinues transmission (Figure 7-2).

7.3

Sequential Read

Sequential reads are initiated in the same way as a ran-
dom read except that after the 24AA164 transmits the
first data byte, the master issues an acknowledge as
opposed to a stop condition in a random read.  This
directs the 24AA164 to transmit the next sequentially
addressed 8-bit word (Figure 7-3).

To provide sequential reads the 24AA164 contains an
internal address pointer which is incremented by one at
the completion of each operation.  This address pointer
allows an entire device memory contents to be serially
read during one operation.  

7.4

Noise Protection

The 24AA164 employs a V

CC

 threshold detector circuit

which disables the internal erase/write logic if the V

CC

is below 1.5 volts at nominal conditions.

The SCL and SDA inputs have Schmitt trigger and filter
circuits which suppress noise spikes to assure proper
device operation even on a noisy bus.

FIGURE 7-1:

CURRENT ADDRESS READ

FIGURE 7-2:

RANDOM READ

FIGURE 7-3:

SEQUENTIAL READ

CONTROL

A

C

K

S

T

A

R

T

BYTE

DATA n

 ACTIVITY

TER

 LINE

 ACTIVITY

S

1 A2 A1 A0 B2 B1 B0

S

CONTROL

BYTE

A

C

K

WORD

ADDRESS (n)

CONTROL

BYTE

S
T
A
R
T

A

C
K

2 A1A0B2B1B0

L

A
C
K

DATA n

DATA n + 1

DATA n + 2

A
C
K

A
C
K

A
C
K

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24AA164

DS21100G-page  8

 2004 Microchip Technology Inc.

8.0

PIN DESCRIPTIONS

8.1

SDA Serial Address/Data Input/Output

This is a Bi-directional pin used to transfer addresses
and data into and data out of the device.  It is an open
drain terminal, therefore the SDA bus requires a pullup
resistor to V

CC

 (typical 10K

 for 100 kHz, 2 K

 for

400 kHz).

For normal data transfer SDA is allowed to change only
during SCL low.  Changes during SCL high are
reserved for indicating the START and STOP condi-
tions.

8.2

SCL Serial Clock 

This input is used to synchronize the data transfer from
and to the device.

8.3

WP

This pin must be connected to either V

SS

 or V

CC

.

If tied to V

SS

, normal memory operation is enabled

(read/write the entire memory 000-7FF).

If tied to V

CC

, WRITE operations are inhibited.  The

entire memory will be write-protected.  Read operations
are not affected.

This feature allows the user to use the 24AA164 as a
serial ROM when WP is enabled (tied to V

CC

).

8.4

A0, A1, A2

These pins are used to configure the proper chip
address in multiple-chip applications (more than one
24AA164 on the same bus).  The levels on these pins
are compared to the corresponding bits in the slave
address. The chip is selected if the compare is true.  

Up to eight 24AA164s may be connected to the same
bus.  These pins must be connected to either V

SS

 or

V

CC

.

Note:

The level on A1 is compared to the inverse
of the slave address.

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24AA164

24AA164 Product Identification System

To order or to obtain information (e.g., on pricing or delivery), please use the listed part numbers, and refer to the factory or the listed
sales offices.  

Sales and Support

Data Sheets
Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recom-
mended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:
1.

Your local Microchip sales office

2.

The Microchip Corporate Literature Center U.S. FAX: (602) 786-7277

3.

The Microchip Worldwide Site (www.microchip.com)

Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using.

New Customer Notification System
Register on our web site (www.microchip.com/cn) to receive the most current information on our products.

Package:

P = Plastic DIP (300 mil Body), 8-lead

SN = Plastic SOIC (150 mil Body), 8-lead

Temperature 

Blank = 0

°

C to 70

°

Range:

Device:

24AA164

16K I

2

C Serial EEPROM

24AA164T

16K I

2

C Serial EEPROM (Tape and Reel)

24AA164

/P

 2004 Microchip Technology Inc.

DS21100G-page  9

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24AA164

DS21100G-page  10

 2004 Microchip Technology Inc.

NOTES:

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 2004 Microchip Technology Inc.

DS21100G-page  1

FEATURES

• Single supply with operation down to 1.8V
• Low power CMOS technology

- 1 mA active current typical
- 10 

µ

A standby current typical at 5.5V

- 5 

µ

A standby current typical at 3.0V

• Organized as 8 blocks of 256 bytes (8 x 256 x 8)
• 2-wire serial interface bus, I

2

C

 compatible

• Functional address inputs for cascading up to 8 

devices

• Schmitt trigger, filtered inputs for noise suppres-

sion

• Output slope control to eliminate ground bounce
• 100 kHz (1.8V) and 400 kHz (5V) compatibility
• Self-timed write cycle (including auto-erase)
• Page-write buffer for up to 16 bytes
• 2 ms typical write cycle time for page-write
• Hardware write protect for entire memory
• Can be operated as a serial ROM
• Factory programming (QTP) available
• ESD protection > 4,000V
• 1,000,000 Erase/Write cycles guaranteed
• Data retention > 200 years
• 8-pin DIP, 8-lead SOIC packages
• Available for commercial temperature range

DESCRIPTION

The Microchip Technology Inc. 24AA164 is a cascad-
able 16K bit Electrically Erasable PROM.  The device
is organized as eight blocks of 256 x 8-bit memory with
a 2-wire serial interface. Low voltage design permits
operation down to 1.8 volts (end-of-life voltage for most
popular battery technologies) with standby and active
currents of only 5 

µ

A and 1 mA respectively. The

24AA164 also has a page-write capability for up to 16
bytes of data. The 24AA164 is available in the standard
8-pin DIP and 8-lead surface mount SOIC packages.

The three select pins, A0, A1, and A2, function as chip
select inputs and allow up to eight devices to share a
common bus, for up to 128K bits total system
EEPROM.

- Commercial (C):

0°C to +70°C

PACKAGE TYPES

BLOCK DIAGRAM

24
A

A

1

6

4

A0

A1

A2

V

SS

1

2

3

4

8

7

6

5

V

CC

WP

SCL

SDA

24A

A164

A0

A1

A2

V

SS

1

2

3

4

8

7

6

5

V

CC

WP

SCL

SDA

PDIP

8-lead
SOIC

HV GENERATOR

EEPROM ARRAY 

(8 x 256 x 8)

PAGE LATCHES

YDEC

XDEC

SENSE AMP 

R/W CONTROL

MEMORY 

CONTROL 

LOGIC

I/O 

CONTROL 

LOGIC

WP

SDA

SCL

V

CC

V

SS

A0

A2

A1

24AA164

16K 1.8V Cascadable I

2

C

 Serial EEPROM

I

2

C is a trademark of Philips Corporation.

Obsolete Device

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24AA164

DS21100G-page  2

 2004 Microchip Technology Inc.

1.0

ELECTRICAL CHARACTERISTICS

1.1

Maximum Ratings*

V

CC

...................................................................................7.0V

All inputs and outputs w.r.t. V

SS..................

-0.3V to V

CC

 +1.0V

Storage temperature .....................................-65°C to +150°C
Ambient temp. with power applied ................-65°C to +125°C
Soldering temperature of leads (10 seconds) ............. +300°C
ESD protection on all pins

..................................................≥

 4 kV

*Notice: Stresses above those listed under “Maximum ratings”
may cause permanent damage to the device.  This is a stress rat-
ing only and functional operation of the device at those or any
other conditions above those indicated in the operational listings
of this specification is not implied.  Exposure to maximum rating
conditions for extended periods may affect device reliability.

TABLE 1-1:

PIN FUNCTION TABLE

Name

Function

V

SS

Ground

SDA

Serial Address/Data I/O

SCL

Serial Clock

WP

Write Protect Input

V

CC

1.8V to 6.0V Power Supply

A0, A1, A2

Chip Address Inputs

TABLE 1-2:

DC CHARACTERISTICS

FIGURE 1-1:

BUS TIMING START/STOP

V

CC

 = 1.8V to +6.0

Commercial (C):  Tamb = 0°C to +70°C

Parameter

Symbol

Min

Typ

Max

Units

Conditions

WP, SCL and SDA pins:

High level input voltage

V

IH

.7 V

CC

V

Low level input voltage

V

IL

.3  V

CC

V

Hysteresis of Schmitt trigger inputs

V

HYS

.05 V

CC

V

(Note) 

Low level output voltage

V

OL

.40

V

I

OL 

= 3.0 mA, V

CC 

= 1.8V

Input leakage current

I

LI

-10

10

µ

A

V

IN 

= .1V to V

CC

Output leakage current

I

LO

-10

10

µ

A

V

OUT 

= .1V to V

CC

Pin capacitance 
(all inputs/outputs

C

IN

C

OUT

10

pF

V

CC

 

= 5.0V (Note 1)

Tamb = 25°C, F

CLK 

= 1 MHz

Operating current

I

CC

 

Write

I

CC

 

Read




0.5

0.05

3

1

mA
mA
mA
mA

V

CC

 

= 5.5V, SCL = 400 kHz

V

CC

 

= 1.8V, SCL = 100 kHz

V

CC

 

= 5.5V, SCL = 400 kHz

V

CC

 

= 1.8V, SCL = 100 kHz

Standby current

I

CCS




3

100

30

µ

A

µ

A

µ

A

V

CC

 

= 5.5V, SDA = SCL=V

CC

V

CC

 

= 3.0V, SDA = SCL=V

CC

V

CC

 

= 1.8V, SDA = SCL=V

CC

WP = V

SS

Note:

 This parameter is periodically sampled and not 100% tested.

T

SU

:

STA

T

HD

:

STA

V

HYS

T

SU

:

STO

START

STOP

SCL

SDA

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 2004 Microchip Technology Inc.

DS21100G-page  3

24AA164

TABLE 1-3:

AC CHARACTERISTICS

FIGURE 1-2:

BUS TIMING DATA

Parameter

Symbol

STANDARD

MODE

V

CC

 

= 4.5-5.5V

FAST MODE

Units

Remarks

Min

Max

Min

Max

Clock frequency

F

CLK

100

400

kHz

Clock high time

T

HIGH

4000

600

ns

Clock low time

T

LOW

4700

1300

ns

SDA and SCL rise time

T

R

1000

300

ns

(Note 1)

SDA and SCL fall time

T

F

300

300

ns

(Note 1)

START condition hold 
time

T

HD

:

STA

4000

600

ns

After this period the first 
clock pulse is generated

START condition setup 
time

T

SU

:

STA

4700

600

ns

Only relevant for repeated 
START condition

Data input hold time

T

HD

:

DAT

0

0

ns

Data input setup time

T

SU

:

DAT

250

100

ns

STOP condition setup 
time

T

SU

:

STO

4000

600

ns

Output valid from clock

T

AA

3500

900

ns

(Note 2)

Bus free time

T

BUF

4700

1300

ns

Time the bus must be free 
before a new transmission 
can start 

Output fall time from V

IH

 

min to V

IL

 max

T

OF

250

20 + 0.1 

C

B

250

ns

(Note 1), C

B

 

 100 pF

Input filter spike suppres-
sion (SDA and SCL pins)

T

SP

50

50

ns

(Note 3)

Write cycle time

T

WR

10

10

ms

Byte or Page mode

Endurance

1M

1M

cycles

25°C, Vcc = 5.0V, Block 
Mode ((Note 4)

Note 1: Not 100% tested.  C

B

 = total capacitance of one bus line in pF.

2: As a transmitter, the device must provide an internal minimum delay time to bridge the undefined region 

(minimum 300 ns) of the falling edge of SCL to avoid unintended generation of START or STOP conditions.

3: The combined T

SP

 and V

HYS

 =specifications are due to new Schmitt trigger inputs which provide improved 

noise and spike suppression.  This eliminates the need for a T

I

 specification for standard operation.

4: This parameter is not tested but guaranteed by characterization. For endurance estimates in a specific appli-

cation, please consult the Total Endurance Model which can be obtained on our website.

SCL

SDA
IN

SDA
OUT

T

SU

:

STA

T

SP

T

AA

T

F

T

LOW

T

HIGH

T

HD

:

STA

T

HD

:

DAT

T

SU

:

DAT

T

SU

:

STO

T

BUF

T

AA

T

R

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24AA164

DS21100G-page  4

 2004 Microchip Technology Inc.

2.0

FUNCTIONAL DESCRIPTION

The 24AA164 supports aBi-directional two wire bus
and data transmission protocol.  A device that sends
data onto the bus is defined as transmitter, and a
device receiving data as receiver.  The bus has to be
controlled by a master device which generates the
serial clock (SCL), controls the bus access, and gener-
ates the START and STOP conditions, while the
24AA164 works as slave.  Both, master and slave can
operate as transmitter or receiver but the master device
determines which mode is activated.

3.0

BUS CHARACTERISTICS

The following bus protocol has been defined:

• Data transfer may be initiated only when the bus 

is not busy.

• During data transfer, the data line must remain 

stable whenever the clock line is HIGH.  Changes 
in the data line while the clock line is HIGH will be 
interpreted as a START or STOP condition.

Accordingly, the following bus conditions have been
defined (Figure 3-1).

3.1

Bus not Busy (A)

Both data and clock lines remain HIGH.

3.2

Start Data Transfer (B)

A HIGH to LOW transition of the SDA line while the
clock (SCL) is HIGH determines a START condition.  All
commands must be preceded by a START condition.

3.3

Stop Data Transfer (C)

A LOW to HIGH transition of the SDA line while the
clock (SCL) is HIGH determines a STOP condition.  All
operations must be ended with a STOP condition.

3.4

Data Valid (D)

The state of the data line represents valid data when,
after a START condition, the data line is stable for the
duration of the HIGH period of the clock signal.

The data on the line must be changed during the LOW
period of the clock signal.  There is one clock pulse per
bit of data.

Each data transfer is initiated with a START condition
and terminated with a STOP condition.  The number of
the data bytes transferred between the START and
STOP conditions is determined by the master device
and is theoretically unlimited, although only the last 16
will be stored when doing a write operation.  When an
overwrite does occur it will replace data in a first in first
out fashion.

3.5

Acknowledge

Each receiving device, when addressed, is obliged to
generate an acknowledge after the reception of each
byte. The master device must generate an extra clock
pulse which is associated with this acknowledge bit.

The device that acknowledges, has to pull down the
SDA line during the acknowledge clock pulse in such a
way that the SDA line is stable LOW during the HIGH
period of the acknowledge related clock pulse.   Of
course, setup and hold times must be taken into
account.  During  reads, a master must signal an end of
data to the slave by not generating an acknowledge bit
on the last byte that has been clocked out of the slave.
In this case, the slave (24AA164) will leave the data line
HIGH to enable the master to generate the STOP con-
dition.

Note:

The 24AA164 does not generate any
acknowledge bits if an internal program-
ming cycle is in progress.

FIGURE 3-1:

DATA TRANSFER SEQUENCE ON THE SERIAL BUS

SCL

SDA

(A)

(B)

(D)

(D)

(A)

(C)

START

CONDITION

ADDRESS OR

ACKNOWLEDGE

VALID

DATA

ALLOWED

TO CHANGE

STOP

CONDITION

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 2004 Microchip Technology Inc.

DS21100G-page  5

24AA164

3.6

Device Addressing

A control byte is the first byte received following the
start condition from the master device.  The first bit is
always a one.  The next three bits of the control byte
are the device select bits (A2, A1, A0).  They are used
to select which of the eight devices are to be accessed.
The A1 bit must be the inverse of the A1 device select
pin.  

The next three bits of the control byte are the block
select bits (B2, B1, B0).  They are used by the master
device to select which of the eight 256 word blocks of
memory are to be accessed.  These bits are in effect
the three most significant bits of the word address.  

The last bit of the control byte defines the operation to
be performed.  When set to one a read operation is
selected, when set to zero a write operation is selected.
Following the start condition, the 24AA164 looks for the
slave address for the device selected.  Depending on
the state of the R/W bit, the 24AA164 will select a read
or write operation. 

FIGURE 3-2:

CONTROL BYTE 
ALLOCATION

Operation

Control Code

Block Select

R/W

Read

1

A2 A1 A0

Block Address

1

Write

1

A2 A1 A0

Block Address

0

SLAVE ADDRESS

1

A2

A1

A0

B2

B1

B0

R/W A

START

READ/WRITE

MSB

LSB

4.0

WRITE OPERATION

4.1

Byte Write

Following the start condition from the master, the
device code (4 bits), the block address (3 bits), and the
R/W bit which is a logic low is placed onto the bus by
the master transmitter.  This indicates to the addressed
slave receiver that a byte with a word address will fol-
low after it has generated an acknowledge bit during
the ninth clock cycle.  Therefore the next byte transmit-
ted by the master is the word address and will be writ-
ten into the address pointer of the 24AA164.  After
receiving another acknowledge signal from the
24AA164 the master device will transmit the data word
to be written into the addressed memory location.  The
24AA164 acknowledges again and the master gener-
ates a stop condition.  This initiates the internal write
cycle, and during this time the 24AA164 will not gener-
ate acknowledge signals (Figure 4-1).

4.2

Page Write 

The write control byte, word address and the first data
byte are transmitted to the 24AA164 in the same way
as in a byte write.  But instead of generating a stop con-
dition the master transmits up to 16 data bytes to the
24AA164 which are temporarily stored in the on-chip
page buffer and will be written into the memory after the
master has transmitted a stop condition.  After the
receipt of each word, the four lower order address
pointer bits are internally incremented by one.  The
higher order seven bits of the word address remains
constant.  If the master should transmit more than 16
words prior to generating the stop condition, the
address counter will roll over and the previously
received data will be overwritten.  As with the byte write
operation, once the stop condition is received an inter-
nal write cycle will begin (Figure 4-2).

Note:

Page write operations are limited to writing
bytes within a single physical page,
regardless of the number of bytes actually
being written. Physical page boundaries
start at addresses that are integer multiples
of the page buffer size (or ‘page size’) and
end at addresses that are integer multiples
of [page size - 1]. If a page write command
attempts to write across a physical page
boundary, the result is that the data wraps
around to the beginning of the current page
(overwriting data previously stored there),
instead of being written to the next page as
might be expected. It is therefore neces-
sary for the application software to prevent
page write operations that would attempt to
cross a page boundary.

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24AA164

DS21100G-page  6

 2004 Microchip Technology Inc.

FIGURE 4-1:

BYTE WRITE

FIGURE 4-2:

PAGE WRITE

S
T
O
P

SDA LINE

P

DATA

S

T

A

R

T

CONTROL

BYTE

S

WORD

ADDRESS

BUS ACTIVITY:
MASTER

BUS ACTIVITY:

A

C

K

A

C

K

A

C

K

1 A2

B0

A1 A0 B2 B1

S
T
O
P

SDA LINE

P

DATA n

S

T

A
R

T

CONTROL

BYTE

WORD

ADDRESS (n)

BUS ACTIVITY:
MASTER

BUS ACTIVITY:

A
C
K

A
C
K

A
C
K

DATA n + 1

A
C
K

DATA n + 15

A
C
K

S

A2

B0

A1 A0 B2 B1

5.0

ACKNOWLEDGE POLLING

Since the device will not acknowledge during a write
cycle, this can be used to determine when the cycle is
complete (this feature can be used to maximize bus
throughput).  Once the stop condition for a write com-
mand has been issued from the master, the device ini-
tiates the internally timed write cycle.  ACK polling can
be initiated immediately.  This involves the master
sending a start condition followed by the control byte for
a write command (R/W = 0).  If the device is still busy
with the write cycle, then no ACK will be returned.  If the
cycle is complete, then the device will return the ACK
and the master can then proceed with the next read or
write command.  See Figure 5-1 for flow diagram.

FIGURE 5-1:

ACKNOWLEDGE POLLING 
FLOW

6.0

WRITE PROTECTION

The 24AA164 can be used as a serial ROM when the
WP pin is connected to V

CC

.  Programming will be

inhibited and the entire memory will be write-protected.

Send

Write Command

Send Stop

Condition to

Initiate Write Cycle

Send Start

Send Control Byte

with R/W = 0

Did Device

Acknowledge

(ACK = 0)?

Next

Operation

NO

YES

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 2004 Microchip Technology Inc.

DS21100G-page  7

24AA164

7.0

READ OPERATION

Read operations are initiated in the same way as write
operations with the exception that the R/W bit of the slave
address is set to one.  There are three basic types of read
operations: current address  read, random read, and
sequential read.

7.1

Current Address Read

The 24AA164 contains an address counter that maintains
the address of the last word accessed, internally incre-
mented by one. Therefore, if the previous access  (either a
read or write operation) was to address n, the next current
address read operation would access data from address n
+ 1. Upon receipt of the slave address with R/W bit set to
one, the 24AA164 issues an acknowledge and transmits
the 8-bit data word. The master will not acknowledge the
transfer but does generate a stop condition and the
24AA164 discontinues transmission (Figure 7-1).

7.2

Random Read

Random read operations allow the master to access any
memory location in a random manner.  To perform this
type of read operation, first the word address must be set.
This is done by sending the word address to the 24AA164
as part of a write operation.  After the word address is sent,
the master generates a start condition following the
acknowledge.  This terminates the write operation, but not
before the internal address pointer is set.  Then the master
issues the control byte again but with the R/W bit set to a
one. The 24AA164 will then issue an acknowledge and
transmits the 8-bit data word.  The master will not acknowl-
edge the transfer but does generate a stop condition and
the 24AA164 discontinues transmission (Figure 7-2).

7.3

Sequential Read

Sequential reads are initiated in the same way as a ran-
dom read except that after the 24AA164 transmits the
first data byte, the master issues an acknowledge as
opposed to a stop condition in a random read.  This
directs the 24AA164 to transmit the next sequentially
addressed 8-bit word (Figure 7-3).

To provide sequential reads the 24AA164 contains an
internal address pointer which is incremented by one at
the completion of each operation.  This address pointer
allows an entire device memory contents to be serially
read during one operation.  

7.4

Noise Protection

The 24AA164 employs a V

CC

 threshold detector circuit

which disables the internal erase/write logic if the V

CC

is below 1.5 volts at nominal conditions.

The SCL and SDA inputs have Schmitt trigger and filter
circuits which suppress noise spikes to assure proper
device operation even on a noisy bus.

FIGURE 7-1:

CURRENT ADDRESS READ

FIGURE 7-2:

RANDOM READ

FIGURE 7-3:

SEQUENTIAL READ

CONTROL

A

C

K

S

T

A

R

T

BYTE

DATA n

 ACTIVITY

TER

 LINE

 ACTIVITY

S

1 A2 A1 A0 B2 B1 B0

S

CONTROL

BYTE

A

C

K

WORD

ADDRESS (n)

CONTROL

BYTE

S
T
A
R
T

A

C
K

2 A1A0B2B1B0

L

A
C
K

DATA n

DATA n + 1

DATA n + 2

A
C
K

A
C
K

A
C
K

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24AA164

DS21100G-page  8

 2004 Microchip Technology Inc.

8.0

PIN DESCRIPTIONS

8.1

SDA Serial Address/Data Input/Output

This is a Bi-directional pin used to transfer addresses
and data into and data out of the device.  It is an open
drain terminal, therefore the SDA bus requires a pullup
resistor to V

CC

 (typical 10K

 for 100 kHz, 2 K

 for

400 kHz).

For normal data transfer SDA is allowed to change only
during SCL low.  Changes during SCL high are
reserved for indicating the START and STOP condi-
tions.

8.2

SCL Serial Clock 

This input is used to synchronize the data transfer from
and to the device.

8.3

WP

This pin must be connected to either V

SS

 or V

CC

.

If tied to V

SS

, normal memory operation is enabled

(read/write the entire memory 000-7FF).

If tied to V

CC

, WRITE operations are inhibited.  The

entire memory will be write-protected.  Read operations
are not affected.

This feature allows the user to use the 24AA164 as a
serial ROM when WP is enabled (tied to V

CC

).

8.4

A0, A1, A2

These pins are used to configure the proper chip
address in multiple-chip applications (more than one
24AA164 on the same bus).  The levels on these pins
are compared to the corresponding bits in the slave
address. The chip is selected if the compare is true.  

Up to eight 24AA164s may be connected to the same
bus.  These pins must be connected to either V

SS

 or

V

CC

.

Note:

The level on A1 is compared to the inverse
of the slave address.

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24AA164

24AA164 Product Identification System

To order or to obtain information (e.g., on pricing or delivery), please use the listed part numbers, and refer to the factory or the listed
sales offices.  

Sales and Support

Data Sheets
Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recom-
mended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:
1.

Your local Microchip sales office

2.

The Microchip Corporate Literature Center U.S. FAX: (602) 786-7277

3.

The Microchip Worldwide Site (www.microchip.com)

Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using.

New Customer Notification System
Register on our web site (www.microchip.com/cn) to receive the most current information on our products.

Package:

P = Plastic DIP (300 mil Body), 8-lead

SN = Plastic SOIC (150 mil Body), 8-lead

Temperature 

Blank = 0

°

C to 70

°

Range:

Device:

24AA164

16K I

2

C Serial EEPROM

24AA164T

16K I

2

C Serial EEPROM (Tape and Reel)

24AA164

/P

 2004 Microchip Technology Inc.

DS21100G-page  9

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24AA164

DS21100G-page  10

 2004 Microchip Technology Inc.

NOTES:

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 2004 Microchip Technology Inc.

DS21100G-page  1

FEATURES

• Single supply with operation down to 1.8V
• Low power CMOS technology

- 1 mA active current typical
- 10 

µ

A standby current typical at 5.5V

- 5 

µ

A standby current typical at 3.0V

• Organized as 8 blocks of 256 bytes (8 x 256 x 8)
• 2-wire serial interface bus, I

2

C

 compatible

• Functional address inputs for cascading up to 8 

devices

• Schmitt trigger, filtered inputs for noise suppres-

sion

• Output slope control to eliminate ground bounce
• 100 kHz (1.8V) and 400 kHz (5V) compatibility
• Self-timed write cycle (including auto-erase)
• Page-write buffer for up to 16 bytes
• 2 ms typical write cycle time for page-write
• Hardware write protect for entire memory
• Can be operated as a serial ROM
• Factory programming (QTP) available
• ESD protection > 4,000V
• 1,000,000 Erase/Write cycles guaranteed
• Data retention > 200 years
• 8-pin DIP, 8-lead SOIC packages
• Available for commercial temperature range

DESCRIPTION

The Microchip Technology Inc. 24AA164 is a cascad-
able 16K bit Electrically Erasable PROM.  The device
is organized as eight blocks of 256 x 8-bit memory with
a 2-wire serial interface. Low voltage design permits
operation down to 1.8 volts (end-of-life voltage for most
popular battery technologies) with standby and active
currents of only 5 

µ

A and 1 mA respectively. The

24AA164 also has a page-write capability for up to 16
bytes of data. The 24AA164 is available in the standard
8-pin DIP and 8-lead surface mount SOIC packages.

The three select pins, A0, A1, and A2, function as chip
select inputs and allow up to eight devices to share a
common bus, for up to 128K bits total system
EEPROM.

- Commercial (C):

0°C to +70°C

PACKAGE TYPES

BLOCK DIAGRAM

24
A

A

1

6

4

A0

A1

A2

V

SS

1

2

3

4

8

7

6

5

V

CC

WP

SCL

SDA

24A

A164

A0

A1

A2

V

SS

1

2

3

4

8

7

6

5

V

CC

WP

SCL

SDA

PDIP

8-lead
SOIC

HV GENERATOR

EEPROM ARRAY 

(8 x 256 x 8)

PAGE LATCHES

YDEC

XDEC

SENSE AMP 

R/W CONTROL

MEMORY 

CONTROL 

LOGIC

I/O 

CONTROL 

LOGIC

WP

SDA

SCL

V

CC

V

SS

A0

A2

A1

24AA164

16K 1.8V Cascadable I

2

C

 Serial EEPROM

I

2

C is a trademark of Philips Corporation.

Obsolete Device

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24AA164

DS21100G-page  2

 2004 Microchip Technology Inc.

1.0

ELECTRICAL CHARACTERISTICS

1.1

Maximum Ratings*

V

CC

...................................................................................7.0V

All inputs and outputs w.r.t. V

SS..................

-0.3V to V

CC

 +1.0V

Storage temperature .....................................-65°C to +150°C
Ambient temp. with power applied ................-65°C to +125°C
Soldering temperature of leads (10 seconds) ............. +300°C
ESD protection on all pins

..................................................≥

 4 kV

*Notice: Stresses above those listed under “Maximum ratings”
may cause permanent damage to the device.  This is a stress rat-
ing only and functional operation of the device at those or any
other conditions above those indicated in the operational listings
of this specification is not implied.  Exposure to maximum rating
conditions for extended periods may affect device reliability.

TABLE 1-1:

PIN FUNCTION TABLE

Name

Function

V

SS

Ground

SDA

Serial Address/Data I/O

SCL

Serial Clock

WP

Write Protect Input

V

CC

1.8V to 6.0V Power Supply

A0, A1, A2

Chip Address Inputs

TABLE 1-2:

DC CHARACTERISTICS

FIGURE 1-1:

BUS TIMING START/STOP

V

CC

 = 1.8V to +6.0

Commercial (C):  Tamb = 0°C to +70°C

Parameter

Symbol

Min

Typ

Max

Units

Conditions

WP, SCL and SDA pins:

High level input voltage

V

IH

.7 V

CC

V

Low level input voltage

V

IL

.3  V

CC

V

Hysteresis of Schmitt trigger inputs

V

HYS

.05 V

CC

V

(Note) 

Low level output voltage

V

OL

.40

V

I

OL 

= 3.0 mA, V

CC 

= 1.8V

Input leakage current

I

LI

-10

10

µ

A

V

IN 

= .1V to V

CC

Output leakage current

I

LO

-10

10

µ

A

V

OUT 

= .1V to V

CC

Pin capacitance 
(all inputs/outputs

C

IN

C

OUT

10

pF

V

CC

 

= 5.0V (Note 1)

Tamb = 25°C, F

CLK 

= 1 MHz

Operating current

I

CC

 

Write

I

CC

 

Read




0.5

0.05

3

1

mA
mA
mA
mA

V

CC

 

= 5.5V, SCL = 400 kHz

V

CC

 

= 1.8V, SCL = 100 kHz

V

CC

 

= 5.5V, SCL = 400 kHz

V

CC

 

= 1.8V, SCL = 100 kHz

Standby current

I

CCS




3

100

30

µ

A

µ

A

µ

A

V

CC

 

= 5.5V, SDA = SCL=V

CC

V

CC

 

= 3.0V, SDA = SCL=V

CC

V

CC

 

= 1.8V, SDA = SCL=V

CC

WP = V

SS

Note:

 This parameter is periodically sampled and not 100% tested.

T

SU

:

STA

T

HD

:

STA

V

HYS

T

SU

:

STO

START

STOP

SCL

SDA

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 2004 Microchip Technology Inc.

DS21100G-page  3

24AA164

TABLE 1-3:

AC CHARACTERISTICS

FIGURE 1-2:

BUS TIMING DATA

Parameter

Symbol

STANDARD

MODE

V

CC

 

= 4.5-5.5V

FAST MODE

Units

Remarks

Min

Max

Min

Max

Clock frequency

F

CLK

100

400

kHz

Clock high time

T

HIGH

4000

600

ns

Clock low time

T

LOW

4700

1300

ns

SDA and SCL rise time

T

R

1000

300

ns

(Note 1)

SDA and SCL fall time

T

F

300

300

ns

(Note 1)

START condition hold 
time

T

HD

:

STA

4000

600

ns

After this period the first 
clock pulse is generated

START condition setup 
time

T

SU

:

STA

4700

600

ns

Only relevant for repeated 
START condition

Data input hold time

T

HD

:

DAT

0

0

ns

Data input setup time

T

SU

:

DAT

250

100

ns

STOP condition setup 
time

T

SU

:

STO

4000

600

ns

Output valid from clock

T

AA

3500

900

ns

(Note 2)

Bus free time

T

BUF

4700

1300

ns

Time the bus must be free 
before a new transmission 
can start 

Output fall time from V

IH

 

min to V

IL

 max

T

OF

250

20 + 0.1 

C

B

250

ns

(Note 1), C

B

 

 100 pF

Input filter spike suppres-
sion (SDA and SCL pins)

T

SP

50

50

ns

(Note 3)

Write cycle time

T

WR

10

10

ms

Byte or Page mode

Endurance

1M

1M

cycles

25°C, Vcc = 5.0V, Block 
Mode ((Note 4)

Note 1: Not 100% tested.  C

B

 = total capacitance of one bus line in pF.

2: As a transmitter, the device must provide an internal minimum delay time to bridge the undefined region 

(minimum 300 ns) of the falling edge of SCL to avoid unintended generation of START or STOP conditions.

3: The combined T

SP

 and V

HYS

 =specifications are due to new Schmitt trigger inputs which provide improved 

noise and spike suppression.  This eliminates the need for a T

I

 specification for standard operation.

4: This parameter is not tested but guaranteed by characterization. For endurance estimates in a specific appli-

cation, please consult the Total Endurance Model which can be obtained on our website.

SCL

SDA
IN

SDA
OUT

T

SU

:

STA

T

SP

T

AA

T

F

T

LOW

T

HIGH

T

HD

:

STA

T

HD

:

DAT

T

SU

:

DAT

T

SU

:

STO

T

BUF

T

AA

T

R

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24AA164

DS21100G-page  4

 2004 Microchip Technology Inc.

2.0

FUNCTIONAL DESCRIPTION

The 24AA164 supports aBi-directional two wire bus
and data transmission protocol.  A device that sends
data onto the bus is defined as transmitter, and a
device receiving data as receiver.  The bus has to be
controlled by a master device which generates the
serial clock (SCL), controls the bus access, and gener-
ates the START and STOP conditions, while the
24AA164 works as slave.  Both, master and slave can
operate as transmitter or receiver but the master device
determines which mode is activated.

3.0

BUS CHARACTERISTICS

The following bus protocol has been defined:

• Data transfer may be initiated only when the bus 

is not busy.

• During data transfer, the data line must remain 

stable whenever the clock line is HIGH.  Changes 
in the data line while the clock line is HIGH will be 
interpreted as a START or STOP condition.

Accordingly, the following bus conditions have been
defined (Figure 3-1).

3.1

Bus not Busy (A)

Both data and clock lines remain HIGH.

3.2

Start Data Transfer (B)

A HIGH to LOW transition of the SDA line while the
clock (SCL) is HIGH determines a START condition.  All
commands must be preceded by a START condition.

3.3

Stop Data Transfer (C)

A LOW to HIGH transition of the SDA line while the
clock (SCL) is HIGH determines a STOP condition.  All
operations must be ended with a STOP condition.

3.4

Data Valid (D)

The state of the data line represents valid data when,
after a START condition, the data line is stable for the
duration of the HIGH period of the clock signal.

The data on the line must be changed during the LOW
period of the clock signal.  There is one clock pulse per
bit of data.

Each data transfer is initiated with a START condition
and terminated with a STOP condition.  The number of
the data bytes transferred between the START and
STOP conditions is determined by the master device
and is theoretically unlimited, although only the last 16
will be stored when doing a write operation.  When an
overwrite does occur it will replace data in a first in first
out fashion.

3.5

Acknowledge

Each receiving device, when addressed, is obliged to
generate an acknowledge after the reception of each
byte. The master device must generate an extra clock
pulse which is associated with this acknowledge bit.

The device that acknowledges, has to pull down the
SDA line during the acknowledge clock pulse in such a
way that the SDA line is stable LOW during the HIGH
period of the acknowledge related clock pulse.   Of
course, setup and hold times must be taken into
account.  During  reads, a master must signal an end of
data to the slave by not generating an acknowledge bit
on the last byte that has been clocked out of the slave.
In this case, the slave (24AA164) will leave the data line
HIGH to enable the master to generate the STOP con-
dition.

Note:

The 24AA164 does not generate any
acknowledge bits if an internal program-
ming cycle is in progress.

FIGURE 3-1:

DATA TRANSFER SEQUENCE ON THE SERIAL BUS

SCL

SDA

(A)

(B)

(D)

(D)

(A)

(C)

START

CONDITION

ADDRESS OR

ACKNOWLEDGE

VALID

DATA

ALLOWED

TO CHANGE

STOP

CONDITION

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 2004 Microchip Technology Inc.

DS21100G-page  5

24AA164

3.6

Device Addressing

A control byte is the first byte received following the
start condition from the master device.  The first bit is
always a one.  The next three bits of the control byte
are the device select bits (A2, A1, A0).  They are used
to select which of the eight devices are to be accessed.
The A1 bit must be the inverse of the A1 device select
pin.  

The next three bits of the control byte are the block
select bits (B2, B1, B0).  They are used by the master
device to select which of the eight 256 word blocks of
memory are to be accessed.  These bits are in effect
the three most significant bits of the word address.  

The last bit of the control byte defines the operation to
be performed.  When set to one a read operation is
selected, when set to zero a write operation is selected.
Following the start condition, the 24AA164 looks for the
slave address for the device selected.  Depending on
the state of the R/W bit, the 24AA164 will select a read
or write operation. 

FIGURE 3-2:

CONTROL BYTE 
ALLOCATION

Operation

Control Code

Block Select

R/W

Read

1

A2 A1 A0

Block Address

1

Write

1

A2 A1 A0

Block Address

0

SLAVE ADDRESS

1

A2

A1

A0

B2

B1

B0

R/W A

START

READ/WRITE

MSB

LSB

4.0

WRITE OPERATION

4.1

Byte Write

Following the start condition from the master, the
device code (4 bits), the block address (3 bits), and the
R/W bit which is a logic low is placed onto the bus by
the master transmitter.  This indicates to the addressed
slave receiver that a byte with a word address will fol-
low after it has generated an acknowledge bit during
the ninth clock cycle.  Therefore the next byte transmit-
ted by the master is the word address and will be writ-
ten into the address pointer of the 24AA164.  After
receiving another acknowledge signal from the
24AA164 the master device will transmit the data word
to be written into the addressed memory location.  The
24AA164 acknowledges again and the master gener-
ates a stop condition.  This initiates the internal write
cycle, and during this time the 24AA164 will not gener-
ate acknowledge signals (Figure 4-1).

4.2

Page Write 

The write control byte, word address and the first data
byte are transmitted to the 24AA164 in the same way
as in a byte write.  But instead of generating a stop con-
dition the master transmits up to 16 data bytes to the
24AA164 which are temporarily stored in the on-chip
page buffer and will be written into the memory after the
master has transmitted a stop condition.  After the
receipt of each word, the four lower order address
pointer bits are internally incremented by one.  The
higher order seven bits of the word address remains
constant.  If the master should transmit more than 16
words prior to generating the stop condition, the
address counter will roll over and the previously
received data will be overwritten.  As with the byte write
operation, once the stop condition is received an inter-
nal write cycle will begin (Figure 4-2).

Note:

Page write operations are limited to writing
bytes within a single physical page,
regardless of the number of bytes actually
being written. Physical page boundaries
start at addresses that are integer multiples
of the page buffer size (or ‘page size’) and
end at addresses that are integer multiples
of [page size - 1]. If a page write command
attempts to write across a physical page
boundary, the result is that the data wraps
around to the beginning of the current page
(overwriting data previously stored there),
instead of being written to the next page as
might be expected. It is therefore neces-
sary for the application software to prevent
page write operations that would attempt to
cross a page boundary.

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24AA164

DS21100G-page  6

 2004 Microchip Technology Inc.

FIGURE 4-1:

BYTE WRITE

FIGURE 4-2:

PAGE WRITE

S
T
O
P

SDA LINE

P

DATA

S

T

A

R

T

CONTROL

BYTE

S

WORD

ADDRESS

BUS ACTIVITY:
MASTER

BUS ACTIVITY:

A

C

K

A

C

K

A

C

K

1 A2

B0

A1 A0 B2 B1

S
T
O
P

SDA LINE

P

DATA n

S

T

A
R

T

CONTROL

BYTE

WORD

ADDRESS (n)

BUS ACTIVITY:
MASTER

BUS ACTIVITY:

A
C
K

A
C
K

A
C
K

DATA n + 1

A
C
K

DATA n + 15

A
C
K

S

A2

B0

A1 A0 B2 B1

5.0

ACKNOWLEDGE POLLING

Since the device will not acknowledge during a write
cycle, this can be used to determine when the cycle is
complete (this feature can be used to maximize bus
throughput).  Once the stop condition for a write com-
mand has been issued from the master, the device ini-
tiates the internally timed write cycle.  ACK polling can
be initiated immediately.  This involves the master
sending a start condition followed by the control byte for
a write command (R/W = 0).  If the device is still busy
with the write cycle, then no ACK will be returned.  If the
cycle is complete, then the device will return the ACK
and the master can then proceed with the next read or
write command.  See Figure 5-1 for flow diagram.

FIGURE 5-1:

ACKNOWLEDGE POLLING 
FLOW

6.0

WRITE PROTECTION

The 24AA164 can be used as a serial ROM when the
WP pin is connected to V

CC

.  Programming will be

inhibited and the entire memory will be write-protected.

Send

Write Command

Send Stop

Condition to

Initiate Write Cycle

Send Start

Send Control Byte

with R/W = 0

Did Device

Acknowledge

(ACK = 0)?

Next

Operation

NO

YES

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 2004 Microchip Technology Inc.

DS21100G-page  7

24AA164

7.0

READ OPERATION

Read operations are initiated in the same way as write
operations with the exception that the R/W bit of the slave
address is set to one.  There are three basic types of read
operations: current address  read, random read, and
sequential read.

7.1

Current Address Read

The 24AA164 contains an address counter that maintains
the address of the last word accessed, internally incre-
mented by one. Therefore, if the previous access  (either a
read or write operation) was to address n, the next current
address read operation would access data from address n
+ 1. Upon receipt of the slave address with R/W bit set to
one, the 24AA164 issues an acknowledge and transmits
the 8-bit data word. The master will not acknowledge the
transfer but does generate a stop condition and the
24AA164 discontinues transmission (Figure 7-1).

7.2

Random Read

Random read operations allow the master to access any
memory location in a random manner.  To perform this
type of read operation, first the word address must be set.
This is done by sending the word address to the 24AA164
as part of a write operation.  After the word address is sent,
the master generates a start condition following the
acknowledge.  This terminates the write operation, but not
before the internal address pointer is set.  Then the master
issues the control byte again but with the R/W bit set to a
one. The 24AA164 will then issue an acknowledge and
transmits the 8-bit data word.  The master will not acknowl-
edge the transfer but does generate a stop condition and
the 24AA164 discontinues transmission (Figure 7-2).

7.3

Sequential Read

Sequential reads are initiated in the same way as a ran-
dom read except that after the 24AA164 transmits the
first data byte, the master issues an acknowledge as
opposed to a stop condition in a random read.  This
directs the 24AA164 to transmit the next sequentially
addressed 8-bit word (Figure 7-3).

To provide sequential reads the 24AA164 contains an
internal address pointer which is incremented by one at
the completion of each operation.  This address pointer
allows an entire device memory contents to be serially
read during one operation.  

7.4

Noise Protection

The 24AA164 employs a V

CC

 threshold detector circuit

which disables the internal erase/write logic if the V

CC

is below 1.5 volts at nominal conditions.

The SCL and SDA inputs have Schmitt trigger and filter
circuits which suppress noise spikes to assure proper
device operation even on a noisy bus.

FIGURE 7-1:

CURRENT ADDRESS READ

FIGURE 7-2:

RANDOM READ

FIGURE 7-3:

SEQUENTIAL READ

CONTROL

A

C

K

S

T

A

R

T

BYTE

DATA n

 ACTIVITY

TER

 LINE

 ACTIVITY

S

1 A2 A1 A0 B2 B1 B0

S

CONTROL

BYTE

A

C

K

WORD

ADDRESS (n)

CONTROL

BYTE

S
T
A
R
T

A

C
K

2 A1A0B2B1B0

L

A
C
K

DATA n

DATA n + 1

DATA n + 2

A
C
K

A
C
K

A
C
K

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24AA164

DS21100G-page  8

 2004 Microchip Technology Inc.

8.0

PIN DESCRIPTIONS

8.1

SDA Serial Address/Data Input/Output

This is a Bi-directional pin used to transfer addresses
and data into and data out of the device.  It is an open
drain terminal, therefore the SDA bus requires a pullup
resistor to V

CC

 (typical 10K

 for 100 kHz, 2 K

 for

400 kHz).

For normal data transfer SDA is allowed to change only
during SCL low.  Changes during SCL high are
reserved for indicating the START and STOP condi-
tions.

8.2

SCL Serial Clock 

This input is used to synchronize the data transfer from
and to the device.

8.3

WP

This pin must be connected to either V

SS

 or V

CC

.

If tied to V

SS

, normal memory operation is enabled

(read/write the entire memory 000-7FF).

If tied to V

CC

, WRITE operations are inhibited.  The

entire memory will be write-protected.  Read operations
are not affected.

This feature allows the user to use the 24AA164 as a
serial ROM when WP is enabled (tied to V

CC

).

8.4

A0, A1, A2

These pins are used to configure the proper chip
address in multiple-chip applications (more than one
24AA164 on the same bus).  The levels on these pins
are compared to the corresponding bits in the slave
address. The chip is selected if the compare is true.  

Up to eight 24AA164s may be connected to the same
bus.  These pins must be connected to either V

SS

 or

V

CC

.

Note:

The level on A1 is compared to the inverse
of the slave address.

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24AA164

24AA164 Product Identification System

To order or to obtain information (e.g., on pricing or delivery), please use the listed part numbers, and refer to the factory or the listed
sales offices.  

Sales and Support

Data Sheets
Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recom-
mended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:
1.

Your local Microchip sales office

2.

The Microchip Corporate Literature Center U.S. FAX: (602) 786-7277

3.

The Microchip Worldwide Site (www.microchip.com)

Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using.

New Customer Notification System
Register on our web site (www.microchip.com/cn) to receive the most current information on our products.

Package:

P = Plastic DIP (300 mil Body), 8-lead

SN = Plastic SOIC (150 mil Body), 8-lead

Temperature 

Blank = 0

°

C to 70

°

Range:

Device:

24AA164

16K I

2

C Serial EEPROM

24AA164T

16K I

2

C Serial EEPROM (Tape and Reel)

24AA164

/P

 2004 Microchip Technology Inc.

DS21100G-page  9

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24AA164

DS21100G-page  10

 2004 Microchip Technology Inc.

NOTES:

Maker
Microchip Technology Inc.
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