11126H.Book

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 2004 Microchip Technology Inc.

DS11126H-page  1

FEATURES

• Fast Read Access Time—150 ns 

• CMOS Technology for Low Power Dissipation

- 30 mA Active

- 100 

µ

A Standby

• Fast Byte Write Time—200 

µ

s or 1 ms 

• Data Retention >200 years

• Endurance - Minimum 10

4

  Erase/Write Cycles

- Automatic Write Operation

- Internal Control Timer

- Auto-Clear Before Write Operation

- On-Chip Address and Data Latches

• Data Polling

• Chip Clear Operation

• Enhanced Data Protection

- V

CC

 Detector

- Pulse Filter

- Write Inhibit

• 5-Volt-Only Operation

• Organized 512x8 JEDEC standard pinout

- 24-pin Dual-In-Line Package

- 32-pin PLCC Package

• Available for Extended Temperature Ranges:

- Commercial: 0°C to +70°C

- Industrial: -40°C to +85°C

DESCRIPTION

The Microchip Technology Inc. 28C04A is a CMOS 4K
non-volatile electrically Erasable and Programmable
Read Only Memory (EEPROM). The 28C04A is
accessed like a static RAM for the read or write cycles
without the need of external components. During a
“byte write”, the address and data are latched inter-
nally, freeing the microprocessor address and data bus
for other operations. Following the initiation of write
cycle, the device will go to a busy state and automati-
cally clear and write the latched data using an internal
control timer. To determine when a write cycle is com-
plete, the 28C04A uses Data polling. Data polling
allows the user to read the location last written to when
the write operation is complete. CMOS design and pro-
cessing enables this part to be used in systems where
reduced power consumption and reliability are
required. A complete family of packages is offered to
provide the utmost flexibility in applications.

PACKAGE TYPES

BLOCK DIAGRAM

• 1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

A7

A6

A5

A4

A3

A2

A1

A0

I/O0

I/O1

I/O2

V   

Vcc

A8

NC

WE

OE

NC

CE

I/O7

I/O6

I/O5

I/O4

I/O3

SS

A6
A5
A4
A3
A2
A1
A0

NC

I/O0

A8
NC
NC
NC
OE
NC
CE
I/O7
I/O6

A7

NC

NC

NU

Vc

c

W

E

NC

I/O1

I/O2

Vss

NU

I/O3

I/O4

I/O5

14

15

16

17

18

19

20

4

3

2

1

32

31

30

29

28

27

26

25

24

23

22

21

5

6

7

8

9

10

11

12

13

DIP

PLCC

28
C

04A

• Pin 1 indicator on PLCC on top of package

28C

0

4

A

I/O0

I/O7

Input/Output

Buffers

Chip Enable/

Output Enable

Control Logic

CE

OE

Data Protection

Circuitry

A8

Y Gating

4K bit

Cell Matrix

X

Decoder

Y

Decoder

A0

Data

Poll

Auto Erase/Write

Timing

V

CC

V

SS

WE

L
a

t

c
h
e
s

Program Voltage

Generation

28C04A

4K (512 x 8) CMOS EEPROM

Obsolete Device

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28C04A

DS11126H-page  2

 2004 Microchip Technology Inc.

1.0

ELECTRICAL CHARACTERISTICS

1.1

MAXIMUM RATINGS*

V

CC

 and input voltages w.r.t. V

SS

....... -0.6V to + 6.25V

Voltage on OE w.r.t. V

SS

...................... -0.6V to +13.5V

Output Voltage w.r.t. V

SS

.................-0.6V to V

CC

+0.6V

Storage temperature ..........................-65°C to +125°C

Ambient temp. with power applied .......-50°C to +95°C

*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 operation listings of
this specification is not implied.  Exposure to maximum rating con-
ditions for extended periods may affect device reliability.

TABLE 1-1:

PIN FUNCTION TABLE

Name

Function

A0 - A8

Address Inputs

CE

Chip Enable

OE

Output Enable

WE

Write Enable

I/O0 - I/O7

Data Inputs/Outputs

V

CC

+5V Power Supply

V

SS

Ground

NC

No Connect; No Internal Connection

NU

Not Used; No External Connection is 
Allowed

TABLE 1-2:

READ/WRITE OPERATION DC CHARACTERISTICS 

V

CC

 = +5V 

±

10%

Commercial (C): Tamb =

   0°C to +70°C

Industrial       (I): Tamb =  -40°C to +85°C

Parameter

Status

Symbol

Min

Max

Units

Conditions

Input Voltages

Logic ‘1’
Logic ‘0’

V

IH

V

IL

2.0

-0.1

V

CC

+1

0.8

V
V

Input Leakage

I

LI

-10

10

µ

A

V

IN

 = -0.1V to V

CC

+1

Input Capacitance

C

IN

10

pF

V

IN

 = 0V; Tamb = 25°C;

f = 1 MHz

Output Voltages

Logic ‘1’
Logic ‘0’

V

OH

V

OL

2.4

0.45

V
V

I

OH

 = -400 

µ

A

I

OL

 = 2.1 mA

Output Leakage

I

LO

-10

10

µ

A

V

OUT

 = -0.1V 

TO

 V

CC

 + 0.1V

Output Capacitance

C

OUT

12

pF

V

IN

 = 0V; T

AMB

 = 25°C;

f = 1 MHz

Power Supply Current, Active

TTL input

I

CC

30

mA

f = 5 MHz (Note 1)
V

CC

 = 5.5V

Power Supply Current, Standby

TTL input
TTL input

CMOS input

I

CC

(

S

)

TTL

I

CC

(

S

)

TTL

I

CC

(

S

)

CMOS

2
3

100

mA
mA

µ

A

CE = V

IH

 (0°C to +70°C)

CE = V

IH

 (-40°C to +85°C)

CE = V

CC

-0.3 to V

CC

+1

OE  = V

CC

All inputs equal V

CC

 or V

SS

Note 1: AC power supply current above 5 MHz; 1 mA/MHz.

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 2004 Microchip Technology Inc.

DS11126H-page  3

28C04A

TABLE 1-3:

READ OPERATION AC CHARACTERISTICS

FIGURE 1-1:

READ WAVEFORMS

AC Testing Waveform:

V

IH

 = 2.4V; V

IL

 = 0.45V; V

OH

 = 2.0V; V

OL

 = 0.8V

Output Load:

1 TTL Load + 100 pF

Input Rise and Fall Times: 20 ns
Ambient Temperature:

Commercial (C): Tamb =

0°C to +70°C

Industrial 

(I):

Tamb =

-40°C to +85°C

Parameter

Sym

28C04A-15

28C04A-20

28C04A-25

Units

Conditions

Min

Max

Min

Max

Min

Max

Address to Output Delay

t

ACC

150

200

250

ns

OE = CE = V

IL

CE to Output Delay

t

CE

150

200

250

ns

OE = V

IL

OE to Output Delay

t

OE

70

80

100

ns

CE = V

IL

CE to OE High Output Float

t

OFF

0

50

0

55

0

70

ns

Output Hold from Address, CE 
or OE, whichever occurs first

t

OH

0

0

0

ns

Endurance

1M

1M

1M

cycles 25°C, Vcc = 

5.0V, Block 
Mode (Note)

Note: 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 BBS or website.

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28C04A

DS11126H-page  4

 2004 Microchip Technology Inc.

TABLE 1-4:

BYTE WRITE AC CHARACTERISTICS

FIGURE 1-2:

PROGRAMMING WAVEFORMS

AC Testing Waveform:

V

IH

 = 2.4V; V

IL

 = 0.45V; V

OH

 = 2.0V; V

OL

 = 0.8V

Output Load:

1 TTL Load + 100 pF

Input Rise/Fall Times:

20 nsec

Ambient Temperature:

Commercial  (C): Tamb= 0°C to 70°C
Industrial 

(I):

Tamb= -40°C to 85°C

Parameter

Symbol

Min

Max

Units

Remarks

Address Set-Up Time

t

AS

10

ns

Address Hold Time

t

AH

50

ns

Data Set-Up Time

t

DS

50

ns

Data Hold Time

t

DH

10

ns

Write Pulse Width

t

WPL

100

ns

Note 1

Write Pulse High Time

t

WPH

50

ns

OE Hold Time

t

OEH

10

ns

OE Set-Up Time

t

OES

10

ns

Data Valid Time

t

DV

1000

ns

Note 2

Write Cycle Time (28C04A)

t

WC

1

ms

0.5 ms typical

Write Cycle Time (28C04AF)

t

WC

200

µ

s

100 

µ

s typical

Note 1: A write cycle can be initiated be CE or WE going low, whichever occurs last.  The data is latched on the pos-

itive edge of CE or WE, whichever occurs first.

2: Data must be valid within 1000ns max. after a write cycle is initiated and must be stable at least until t

DH

 

after the positive edge of WE or CE, whichever occurs first.

t

AS

t

AH

t

WPL

t

DS

t

DH

t

OES

t

OEH

t

DV

Address

CE, WE

Data In

OE

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

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 2004 Microchip Technology Inc.

DS11126H-page  5

28C04A

FIGURE 1-3:

DATA POLLING WAVEFORMS

FIGURE 1-4:

CHIP CLEAR WAVEFORMS

Address Valid

Last Written

Address Valid

t

ACC

t

CE

t

WPL

t

WPH

t

DV

t

WC

t

OE

True Data Out

Data In

Valid

V

IH

V

IL

Data

OE

WE

CE

Address

I/O7 Out

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

H

V

IH

CE

OE

WE

t

S

t

H

t

W

t

S

=     = 1

µ

s

t

H

= 10ms

t

W

V

IH

V

IL

V

IH

V

IL

= 12.0V 

±

0.5V

V

H

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28C04A

DS11126H-page  6

 2004 Microchip Technology Inc.

2.0

DEVICE OPERATION

The Microchip Technology Inc. 28C04A has four basic
modes of operation—read, standby, write inhibit, and
byte write—as outlined in the following table.

2.1

Read Mode

The 28C04A has two control functions, both of which
must be logically satisfied in order to obtain data at the
outputs. Chip enable (CE) is the power control and
should be used for device selection. Output Enable
(OE) is the output control and is used to gate data to the
output pins independent of device selection. Assuming
that addresses are stable, address access time (t

ACC

)

is equal to the delay from CE  to  output  (t

CE

). Data is

available at the output tOE after the falling edge of OE,
assuming that CE has been low and addresses have
been stable for at least t

ACC

-t

OE

.

2.2

Standby Mode

The 28C04A is placed in the standby mode by applying
a high signal to the CE input. When in the standby
mode, the outputs are in a high impedance state, inde-
pendent of the OE input.

2.3

Data Protection

In order to ensure data integrity, especially during criti-
cal power-up and power-down transitions, the following
enhanced data protection circuits are incorporated:

First, an internal V

CC

 detect (3.3 volts typical) will inhibit

the initiation of non-volatile programming operation
when V

CC

 is less than the V

CC

 detect circuit trip. 

Second, there  is a WE filtering circuit that prevents WE
pulses of less than 10 ns  duration from initiating a write
cycle.

Third, holding WE or CE high or OE low, inhibits a write
cycle during power-on and power-off (V

CC

).

Operation 

Mode

CE

IE

WE

I/O

Read

L

L

H

D

OUT

Standby

H

X

X

High Z

Write Inhibit

H

X

X

High Z

Write Inhibit

X

L

X

High Z

Write Inhibit

X

X

H

High Z

Byte Write

L

H

L

D

IN

Byte Clear

Automatic Before Each “Write”

X = Any TTL level.

2.4

Write Mode

The 28C04A has a write cycle similar to that of a Static
RAM. The write cycle is completely self-timed and initi-
ated by a low going pulse on the WE pin. On the falling
edge of WE, the address information is latched. On ris-
ing edge, the data and the control pins (CE and OE) are
latched. 

2.5

Data Polling

The 28C04A features Data polling to signal the comple-
tion of a byte write cycle. During a write cycle, an
attempted read of the last byte written results in the
data complement of I/O7 (I/O0 to I/O6 are indetermin-
able). After completion of the write cycle, true data is
available. Data polling allows a simple read/compare
operation to determine the status of the chip eliminating
the need for external hardware.

2.6

Chip Clear

All data may be cleared to 1's in a chip clear cycle by
raising OE to 12 volts and bringing the WE and CE low.
This procedure clears all data.

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28C04A

28C04A 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.

Package:

L = Plastic Leaded Chip Carrier (PLCC)

P = Plastic DIP (600mill)

Temperature

Blank = 0

°

C to +70

°

Range:

I

= -40

°

C to +85

°

C

Access Time:

15

150 ns

20

200 ns

25

250 ns

Shipping:

Blank

Tube

T

Tape and Reel “L” only

Option:

Blank = twc = 1ms

F = twc = 200 

µ

s

Device:

28C04A

512 x 8 CMOS EEPROM 

28C04A

F

T

15

/P

 2004 Microchip Technology Inc.

DS11126H-page  7

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28C04A

DS11126H-page  8

 2004 Microchip Technology Inc.

NOTES:

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 2004 Microchip Technology Inc.

DS11126H-page 9

Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical
components in life support systems is not authorized except
with express written approval by Microchip. No licenses are
conveyed, implicitly or otherwise, under any intellectual
property rights.

Trademarks

The Microchip name and logo, the Microchip logo, Accuron, 
dsPIC, K

EE

L

OQ

, micro

ID

, MPLAB, PIC, PICmicro, PICSTART, 

PRO MATE, PowerSmart, rfPIC, and SmartShunt are 
registered trademarks of Microchip Technology Incorporated 
in the U.S.A. and other countries.

AmpLab, FilterLab, MXDEV, MXLAB, PICMASTER, SEEVAL, 
SmartSensor and The Embedded Control Solutions Company 
are registered trademarks of Microchip Technology 
Incorporated in the U.S.A.

Analog-for-the-Digital Age, Application Maestro, dsPICDEM, 
dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, 
FanSense, FlexROM, fuzzyLAB, In-Circuit Serial 
Programming, ICSP, ICEPIC, Migratable Memory, MPASM, 
MPLIB, MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net, 
PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, 
PowerTool, rfLAB, rfPICDEM, Select Mode, Smart Serial, 
SmartTel and Total Endurance are trademarks of Microchip 
Technology Incorporated in the U.S.A. and other countries.

SQTP is a service mark of Microchip Technology Incorporated 
in the U.S.A.

All other trademarks mentioned herein are property of their 
respective companies.

© 2004, Microchip Technology Incorporated, Printed in the 
U.S.A., All Rights Reserved.

 Printed on recycled paper.

Note the following details of the code protection feature on Microchip devices:

Microchip products meet the specification contained in their particular Microchip Data Sheet.

Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the 
intended manner and under normal conditions.

There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our 
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data 
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

Microchip is willing to work with the customer who is concerned about the integrity of their code.

Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not 
mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Microchip received ISO/TS-16949:2002 quality system certification for 
its worldwide headquarters, design and wafer fabrication facilities in 
Chandler and Tempe, Arizona and Mountain View, California in 
October 2003. The Company’s quality system processes and 
procedures are for its PICmicro

®

 

8-bit MCUs, K

EE

L

OQ

®

 

code hopping 

devices, Serial EEPROMs, microperipherals, nonvolatile memory and 
analog products. In addition, Microchip’s quality system for the design 
and manufacture of development systems is ISO 9001:2000 certified.

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 2004 Microchip Technology Inc.

AMERICAS

Corporate Office

2355 West Chandler Blvd.
Chandler, AZ  85224-6199
Tel:  480-792-7200  
Fax:  480-792-7277
Technical Support: 480-792-7627
Web Address: www.microchip.com

Atlanta

3780 Mansell Road, Suite 130
Alpharetta, GA  30022
Tel: 770-640-0034  
Fax: 770-640-0307

Boston

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Westford, MA  01886
Tel: 978-692-3848 
Fax: 978-692-3821

Chicago

333 Pierce Road, Suite 180
Itasca, IL  60143
Tel: 630-285-0071 
Fax: 630-285-0075

Dallas

16200 Addison Road, Suite 255
Addison Plaza
Addison, TX 75001
Tel: 972-818-7423  
Fax: 972-818-2924

Detroit

Tri-Atria Office Building 
32255 Northwestern Highway, Suite 190
Farmington Hills, MI  48334
Tel: 248-538-2250
Fax: 248-538-2260

Kokomo

2767 S. Albright Road 
Kokomo, IN  46902
Tel: 765-864-8360
Fax: 765-864-8387

Los Angeles

25950 Acero St., Suite 200
Mission Viejo, CA  92691
Tel: 949-462-9523  
Fax: 949-462-9608

San Jose

1300 Terra Bella Avenue
Mountain View, CA 94043
Tel: 650-215-1444
Fax: 650-961-0286

Toronto

6285 Northam Drive, Suite 108
Mississauga, Ontario L4V 1X5, Canada
Tel: 905-673-0699  
Fax:  905-673-6509

ASIA/PACIFIC

Australia

Microchip Technology Australia Pty Ltd
Unit 32 41 Rawson Street
Epping 2121, NSW
Sydney, Australia
Tel: 61-2-9868-6733 
Fax: 61-2-9868-6755

China - Beijing

Unit 706B
Wan Tai Bei Hai Bldg.
No. 6 Chaoyangmen Bei Str. 
Beijing, 100027, China
Tel: 86-10-85282100 
Fax: 86-10-85282104

China - Chengdu

Rm. 2401-2402, 24th Floor, 
Ming Xing Financial Tower
No. 88 TIDU Street
Chengdu 610016, China
Tel: 86-28-86766200  
Fax: 86-28-86766599

China - Fuzhou

Unit 28F, World Trade Plaza
No. 71 Wusi Road
Fuzhou 350001, China
Tel: 86-591-7503506  
Fax: 86-591-7503521

China - Hong Kong SAR

Unit 901-6, Tower 2, Metroplaza
223 Hing Fong Road
Kwai Fong, N.T., Hong Kong
Tel: 852-2401-1200  
Fax: 852-2401-3431

China - Shanghai

Room 701, Bldg. B
Far East International Plaza
No. 317 Xian Xia Road
Shanghai, 200051
Tel: 86-21-6275-5700  
Fax: 86-21-6275-5060

China - Shenzhen

Rm. 1812, 18/F, Building A, United Plaza
No. 5022 Binhe Road, Futian District
Shenzhen 518033, China
Tel: 86-755-82901380 
Fax: 86-755-8295-1393

China - Shunde

Room 401, Hongjian Building, No. 2 
Fengxiangnan Road, Ronggui Town, Shunde
District, Foshan City, Guangdong 528303, China
Tel: 86-757-28395507  Fax: 86-757-28395571

China - Qingdao

Rm. B505A, Fullhope Plaza,
No. 12 Hong Kong Central Rd.
Qingdao 266071, China
Tel: 86-532-5027355  Fax: 86-532-5027205

India

Divyasree Chambers
1 Floor, Wing A (A3/A4)
No. 11, O’Shaugnessey Road
Bangalore, 560 025, India
Tel: 91-80-22290061 Fax: 91-80-22290062

Japan

Yusen Shin Yokohama Building 10F
3-17-2, Shin Yokohama, Kohoku-ku,
Yokohama, Kanagawa, 222-0033, Japan
Tel: 81-45-471- 6166  Fax: 81-45-471-6122

Korea

168-1, Youngbo Bldg. 3 Floor
Samsung-Dong, Kangnam-Ku
Seoul, Korea 135-882
Tel: 82-2-554-7200  Fax: 82-2-558-5932 or 
82-2-558-5934

Singapore

200 Middle Road
#07-02 Prime Centre
Singapore, 188980
Tel:  65-6334-8870  Fax: 65-6334-8850

Taiwan

Kaohsiung Branch
30F - 1 No. 8
Min Chuan 2nd Road
Kaohsiung 806, Taiwan
Tel: 886-7-536-4816
Fax: 886-7-536-4817

Taiwan

Taiwan Branch
11F-3, No. 207
Tung Hua North Road
Taipei, 105, Taiwan
Tel: 886-2-2717-7175  Fax: 886-2-2545-0139

Taiwan

Taiwan Branch
13F-3, No. 295, Sec. 2, Kung Fu Road
Hsinchu City 300, Taiwan
Tel: 886-3-572-9526
Fax: 886-3-572-6459

EUROPE

Austria

Durisolstrasse 2
A-4600 Wels
Austria
Tel: 43-7242-2244-399
Fax: 43-7242-2244-393

Denmark

Regus Business Centre
Lautrup hoj 1-3
Ballerup DK-2750 Denmark
Tel: 45-4420-9895 Fax: 45-4420-9910

France

Parc d’Activite du Moulin de Massy
43 Rue du Saule Trapu
Batiment A - ler Etage
91300 Massy, France
Tel: 33-1-69-53-63-20  
Fax: 33-1-69-30-90-79

Germany

Steinheilstrasse 10
D-85737 Ismaning, Germany
Tel: 49-89-627-144-0 
Fax: 49-89-627-144-44

Italy

Via Salvatore Quasimodo, 12
20025 Legnano (MI)
Milan, Italy 
Tel: 39-0331-742611  
Fax: 39-0331-466781

Netherlands

Waegenburghtplein 4
NL-5152 JR, Drunen, Netherlands
Tel: 31-416-690399 
Fax: 31-416-690340

United Kingdom

505 Eskdale Road
Winnersh Triangle
Wokingham 
Berkshire, England RG41 5TU
Tel: 44-118-921-5869
Fax: 44-118-921-5820

07/12/04

W

ORLDWIDE

 S

ALES

 

AND

 S

ERVICE

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 2004 Microchip Technology Inc.

DS11126H-page  1

FEATURES

• Fast Read Access Time—150 ns 

• CMOS Technology for Low Power Dissipation

- 30 mA Active

- 100 

µ

A Standby

• Fast Byte Write Time—200 

µ

s or 1 ms 

• Data Retention >200 years

• Endurance - Minimum 10

4

  Erase/Write Cycles

- Automatic Write Operation

- Internal Control Timer

- Auto-Clear Before Write Operation

- On-Chip Address and Data Latches

• Data Polling

• Chip Clear Operation

• Enhanced Data Protection

- V

CC

 Detector

- Pulse Filter

- Write Inhibit

• 5-Volt-Only Operation

• Organized 512x8 JEDEC standard pinout

- 24-pin Dual-In-Line Package

- 32-pin PLCC Package

• Available for Extended Temperature Ranges:

- Commercial: 0°C to +70°C

- Industrial: -40°C to +85°C

DESCRIPTION

The Microchip Technology Inc. 28C04A is a CMOS 4K
non-volatile electrically Erasable and Programmable
Read Only Memory (EEPROM). The 28C04A is
accessed like a static RAM for the read or write cycles
without the need of external components. During a
“byte write”, the address and data are latched inter-
nally, freeing the microprocessor address and data bus
for other operations. Following the initiation of write
cycle, the device will go to a busy state and automati-
cally clear and write the latched data using an internal
control timer. To determine when a write cycle is com-
plete, the 28C04A uses Data polling. Data polling
allows the user to read the location last written to when
the write operation is complete. CMOS design and pro-
cessing enables this part to be used in systems where
reduced power consumption and reliability are
required. A complete family of packages is offered to
provide the utmost flexibility in applications.

PACKAGE TYPES

BLOCK DIAGRAM

• 1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

A7

A6

A5

A4

A3

A2

A1

A0

I/O0

I/O1

I/O2

V   

Vcc

A8

NC

WE

OE

NC

CE

I/O7

I/O6

I/O5

I/O4

I/O3

SS

A6
A5
A4
A3
A2
A1
A0

NC

I/O0

A8
NC
NC
NC
OE
NC
CE
I/O7
I/O6

A7

NC

NC

NU

Vc

c

W

E

NC

I/O1

I/O2

Vss

NU

I/O3

I/O4

I/O5

14

15

16

17

18

19

20

4

3

2

1

32

31

30

29

28

27

26

25

24

23

22

21

5

6

7

8

9

10

11

12

13

DIP

PLCC

28
C

04A

• Pin 1 indicator on PLCC on top of package

28C

0

4

A

I/O0

I/O7

Input/Output

Buffers

Chip Enable/

Output Enable

Control Logic

CE

OE

Data Protection

Circuitry

A8

Y Gating

4K bit

Cell Matrix

X

Decoder

Y

Decoder

A0

Data

Poll

Auto Erase/Write

Timing

V

CC

V

SS

WE

L
a

t

c
h
e
s

Program Voltage

Generation

28C04A

4K (512 x 8) CMOS EEPROM

Obsolete Device

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28C04A

DS11126H-page  2

 2004 Microchip Technology Inc.

1.0

ELECTRICAL CHARACTERISTICS

1.1

MAXIMUM RATINGS*

V

CC

 and input voltages w.r.t. V

SS

....... -0.6V to + 6.25V

Voltage on OE w.r.t. V

SS

...................... -0.6V to +13.5V

Output Voltage w.r.t. V

SS

.................-0.6V to V

CC

+0.6V

Storage temperature ..........................-65°C to +125°C

Ambient temp. with power applied .......-50°C to +95°C

*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 operation listings of
this specification is not implied.  Exposure to maximum rating con-
ditions for extended periods may affect device reliability.

TABLE 1-1:

PIN FUNCTION TABLE

Name

Function

A0 - A8

Address Inputs

CE

Chip Enable

OE

Output Enable

WE

Write Enable

I/O0 - I/O7

Data Inputs/Outputs

V

CC

+5V Power Supply

V

SS

Ground

NC

No Connect; No Internal Connection

NU

Not Used; No External Connection is 
Allowed

TABLE 1-2:

READ/WRITE OPERATION DC CHARACTERISTICS 

V

CC

 = +5V 

±

10%

Commercial (C): Tamb =

   0°C to +70°C

Industrial       (I): Tamb =  -40°C to +85°C

Parameter

Status

Symbol

Min

Max

Units

Conditions

Input Voltages

Logic ‘1’
Logic ‘0’

V

IH

V

IL

2.0

-0.1

V

CC

+1

0.8

V
V

Input Leakage

I

LI

-10

10

µ

A

V

IN

 = -0.1V to V

CC

+1

Input Capacitance

C

IN

10

pF

V

IN

 = 0V; Tamb = 25°C;

f = 1 MHz

Output Voltages

Logic ‘1’
Logic ‘0’

V

OH

V

OL

2.4

0.45

V
V

I

OH

 = -400 

µ

A

I

OL

 = 2.1 mA

Output Leakage

I

LO

-10

10

µ

A

V

OUT

 = -0.1V 

TO

 V

CC

 + 0.1V

Output Capacitance

C

OUT

12

pF

V

IN

 = 0V; T

AMB

 = 25°C;

f = 1 MHz

Power Supply Current, Active

TTL input

I

CC

30

mA

f = 5 MHz (Note 1)
V

CC

 = 5.5V

Power Supply Current, Standby

TTL input
TTL input

CMOS input

I

CC

(

S

)

TTL

I

CC

(

S

)

TTL

I

CC

(

S

)

CMOS

2
3

100

mA
mA

µ

A

CE = V

IH

 (0°C to +70°C)

CE = V

IH

 (-40°C to +85°C)

CE = V

CC

-0.3 to V

CC

+1

OE  = V

CC

All inputs equal V

CC

 or V

SS

Note 1: AC power supply current above 5 MHz; 1 mA/MHz.

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 2004 Microchip Technology Inc.

DS11126H-page  3

28C04A

TABLE 1-3:

READ OPERATION AC CHARACTERISTICS

FIGURE 1-1:

READ WAVEFORMS

AC Testing Waveform:

V

IH

 = 2.4V; V

IL

 = 0.45V; V

OH

 = 2.0V; V

OL

 = 0.8V

Output Load:

1 TTL Load + 100 pF

Input Rise and Fall Times: 20 ns
Ambient Temperature:

Commercial (C): Tamb =

0°C to +70°C

Industrial 

(I):

Tamb =

-40°C to +85°C

Parameter

Sym

28C04A-15

28C04A-20

28C04A-25

Units

Conditions

Min

Max

Min

Max

Min

Max

Address to Output Delay

t

ACC

150

200

250

ns

OE = CE = V

IL

CE to Output Delay

t

CE

150

200

250

ns

OE = V

IL

OE to Output Delay

t

OE

70

80

100

ns

CE = V

IL

CE to OE High Output Float

t

OFF

0

50

0

55

0

70

ns

Output Hold from Address, CE 
or OE, whichever occurs first

t

OH

0

0

0

ns

Endurance

1M

1M

1M

cycles 25°C, Vcc = 

5.0V, Block 
Mode (Note)

Note: 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 BBS or website.

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28C04A

DS11126H-page  4

 2004 Microchip Technology Inc.

TABLE 1-4:

BYTE WRITE AC CHARACTERISTICS

FIGURE 1-2:

PROGRAMMING WAVEFORMS

AC Testing Waveform:

V

IH

 = 2.4V; V

IL

 = 0.45V; V

OH

 = 2.0V; V

OL

 = 0.8V

Output Load:

1 TTL Load + 100 pF

Input Rise/Fall Times:

20 nsec

Ambient Temperature:

Commercial  (C): Tamb= 0°C to 70°C
Industrial 

(I):

Tamb= -40°C to 85°C

Parameter

Symbol

Min

Max

Units

Remarks

Address Set-Up Time

t

AS

10

ns

Address Hold Time

t

AH

50

ns

Data Set-Up Time

t

DS

50

ns

Data Hold Time

t

DH

10

ns

Write Pulse Width

t

WPL

100

ns

Note 1

Write Pulse High Time

t

WPH

50

ns

OE Hold Time

t

OEH

10

ns

OE Set-Up Time

t

OES

10

ns

Data Valid Time

t

DV

1000

ns

Note 2

Write Cycle Time (28C04A)

t

WC

1

ms

0.5 ms typical

Write Cycle Time (28C04AF)

t

WC

200

µ

s

100 

µ

s typical

Note 1: A write cycle can be initiated be CE or WE going low, whichever occurs last.  The data is latched on the pos-

itive edge of CE or WE, whichever occurs first.

2: Data must be valid within 1000ns max. after a write cycle is initiated and must be stable at least until t

DH

 

after the positive edge of WE or CE, whichever occurs first.

t

AS

t

AH

t

WPL

t

DS

t

DH

t

OES

t

OEH

t

DV

Address

CE, WE

Data In

OE

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

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 2004 Microchip Technology Inc.

DS11126H-page  5

28C04A

FIGURE 1-3:

DATA POLLING WAVEFORMS

FIGURE 1-4:

CHIP CLEAR WAVEFORMS

Address Valid

Last Written

Address Valid

t

ACC

t

CE

t

WPL

t

WPH

t

DV

t

WC

t

OE

True Data Out

Data In

Valid

V

IH

V

IL

Data

OE

WE

CE

Address

I/O7 Out

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

H

V

IH

CE

OE

WE

t

S

t

H

t

W

t

S

=     = 1

µ

s

t

H

= 10ms

t

W

V

IH

V

IL

V

IH

V

IL

= 12.0V 

±

0.5V

V

H

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28C04A

DS11126H-page  6

 2004 Microchip Technology Inc.

2.0

DEVICE OPERATION

The Microchip Technology Inc. 28C04A has four basic
modes of operation—read, standby, write inhibit, and
byte write—as outlined in the following table.

2.1

Read Mode

The 28C04A has two control functions, both of which
must be logically satisfied in order to obtain data at the
outputs. Chip enable (CE) is the power control and
should be used for device selection. Output Enable
(OE) is the output control and is used to gate data to the
output pins independent of device selection. Assuming
that addresses are stable, address access time (t

ACC

)

is equal to the delay from CE  to  output  (t

CE

). Data is

available at the output tOE after the falling edge of OE,
assuming that CE has been low and addresses have
been stable for at least t

ACC

-t

OE

.

2.2

Standby Mode

The 28C04A is placed in the standby mode by applying
a high signal to the CE input. When in the standby
mode, the outputs are in a high impedance state, inde-
pendent of the OE input.

2.3

Data Protection

In order to ensure data integrity, especially during criti-
cal power-up and power-down transitions, the following
enhanced data protection circuits are incorporated:

First, an internal V

CC

 detect (3.3 volts typical) will inhibit

the initiation of non-volatile programming operation
when V

CC

 is less than the V

CC

 detect circuit trip. 

Second, there  is a WE filtering circuit that prevents WE
pulses of less than 10 ns  duration from initiating a write
cycle.

Third, holding WE or CE high or OE low, inhibits a write
cycle during power-on and power-off (V

CC

).

Operation 

Mode

CE

IE

WE

I/O

Read

L

L

H

D

OUT

Standby

H

X

X

High Z

Write Inhibit

H

X

X

High Z

Write Inhibit

X

L

X

High Z

Write Inhibit

X

X

H

High Z

Byte Write

L

H

L

D

IN

Byte Clear

Automatic Before Each “Write”

X = Any TTL level.

2.4

Write Mode

The 28C04A has a write cycle similar to that of a Static
RAM. The write cycle is completely self-timed and initi-
ated by a low going pulse on the WE pin. On the falling
edge of WE, the address information is latched. On ris-
ing edge, the data and the control pins (CE and OE) are
latched. 

2.5

Data Polling

The 28C04A features Data polling to signal the comple-
tion of a byte write cycle. During a write cycle, an
attempted read of the last byte written results in the
data complement of I/O7 (I/O0 to I/O6 are indetermin-
able). After completion of the write cycle, true data is
available. Data polling allows a simple read/compare
operation to determine the status of the chip eliminating
the need for external hardware.

2.6

Chip Clear

All data may be cleared to 1's in a chip clear cycle by
raising OE to 12 volts and bringing the WE and CE low.
This procedure clears all data.

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28C04A

28C04A 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.

Package:

L = Plastic Leaded Chip Carrier (PLCC)

P = Plastic DIP (600mill)

Temperature

Blank = 0

°

C to +70

°

Range:

I

= -40

°

C to +85

°

C

Access Time:

15

150 ns

20

200 ns

25

250 ns

Shipping:

Blank

Tube

T

Tape and Reel “L” only

Option:

Blank = twc = 1ms

F = twc = 200 

µ

s

Device:

28C04A

512 x 8 CMOS EEPROM 

28C04A

F

T

15

/P

 2004 Microchip Technology Inc.

DS11126H-page  7

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28C04A

DS11126H-page  8

 2004 Microchip Technology Inc.

NOTES:

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 2004 Microchip Technology Inc.

DS11126H-page 9

Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical
components in life support systems is not authorized except
with express written approval by Microchip. No licenses are
conveyed, implicitly or otherwise, under any intellectual
property rights.

Trademarks

The Microchip name and logo, the Microchip logo, Accuron, 
dsPIC, K

EE

L

OQ

, micro

ID

, MPLAB, PIC, PICmicro, PICSTART, 

PRO MATE, PowerSmart, rfPIC, and SmartShunt are 
registered trademarks of Microchip Technology Incorporated 
in the U.S.A. and other countries.

AmpLab, FilterLab, MXDEV, MXLAB, PICMASTER, SEEVAL, 
SmartSensor and The Embedded Control Solutions Company 
are registered trademarks of Microchip Technology 
Incorporated in the U.S.A.

Analog-for-the-Digital Age, Application Maestro, dsPICDEM, 
dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, 
FanSense, FlexROM, fuzzyLAB, In-Circuit Serial 
Programming, ICSP, ICEPIC, Migratable Memory, MPASM, 
MPLIB, MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net, 
PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, 
PowerTool, rfLAB, rfPICDEM, Select Mode, Smart Serial, 
SmartTel and Total Endurance are trademarks of Microchip 
Technology Incorporated in the U.S.A. and other countries.

SQTP is a service mark of Microchip Technology Incorporated 
in the U.S.A.

All other trademarks mentioned herein are property of their 
respective companies.

© 2004, Microchip Technology Incorporated, Printed in the 
U.S.A., All Rights Reserved.

 Printed on recycled paper.

Note the following details of the code protection feature on Microchip devices:

Microchip products meet the specification contained in their particular Microchip Data Sheet.

Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the 
intended manner and under normal conditions.

There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our 
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data 
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

Microchip is willing to work with the customer who is concerned about the integrity of their code.

Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not 
mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Microchip received ISO/TS-16949:2002 quality system certification for 
its worldwide headquarters, design and wafer fabrication facilities in 
Chandler and Tempe, Arizona and Mountain View, California in 
October 2003. The Company’s quality system processes and 
procedures are for its PICmicro

®

 

8-bit MCUs, K

EE

L

OQ

®

 

code hopping 

devices, Serial EEPROMs, microperipherals, nonvolatile memory and 
analog products. In addition, Microchip’s quality system for the design 
and manufacture of development systems is ISO 9001:2000 certified.

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 2004 Microchip Technology Inc.

AMERICAS

Corporate Office

2355 West Chandler Blvd.
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Tel:  480-792-7200  
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Technical Support: 480-792-7627
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Tel: 770-640-0034  
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Tri-Atria Office Building 
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82-2-558-5934

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EUROPE

Austria

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Denmark

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France

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Germany

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Italy

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Netherlands

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United Kingdom

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07/12/04

W

ORLDWIDE

 S

ALES

 

AND

 S

ERVICE

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 2004 Microchip Technology Inc.

DS11126H-page  1

FEATURES

• Fast Read Access Time—150 ns 

• CMOS Technology for Low Power Dissipation

- 30 mA Active

- 100 

µ

A Standby

• Fast Byte Write Time—200 

µ

s or 1 ms 

• Data Retention >200 years

• Endurance - Minimum 10

4

  Erase/Write Cycles

- Automatic Write Operation

- Internal Control Timer

- Auto-Clear Before Write Operation

- On-Chip Address and Data Latches

• Data Polling

• Chip Clear Operation

• Enhanced Data Protection

- V

CC

 Detector

- Pulse Filter

- Write Inhibit

• 5-Volt-Only Operation

• Organized 512x8 JEDEC standard pinout

- 24-pin Dual-In-Line Package

- 32-pin PLCC Package

• Available for Extended Temperature Ranges:

- Commercial: 0°C to +70°C

- Industrial: -40°C to +85°C

DESCRIPTION

The Microchip Technology Inc. 28C04A is a CMOS 4K
non-volatile electrically Erasable and Programmable
Read Only Memory (EEPROM). The 28C04A is
accessed like a static RAM for the read or write cycles
without the need of external components. During a
“byte write”, the address and data are latched inter-
nally, freeing the microprocessor address and data bus
for other operations. Following the initiation of write
cycle, the device will go to a busy state and automati-
cally clear and write the latched data using an internal
control timer. To determine when a write cycle is com-
plete, the 28C04A uses Data polling. Data polling
allows the user to read the location last written to when
the write operation is complete. CMOS design and pro-
cessing enables this part to be used in systems where
reduced power consumption and reliability are
required. A complete family of packages is offered to
provide the utmost flexibility in applications.

PACKAGE TYPES

BLOCK DIAGRAM

• 1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

A7

A6

A5

A4

A3

A2

A1

A0

I/O0

I/O1

I/O2

V   

Vcc

A8

NC

WE

OE

NC

CE

I/O7

I/O6

I/O5

I/O4

I/O3

SS

A6
A5
A4
A3
A2
A1
A0

NC

I/O0

A8
NC
NC
NC
OE
NC
CE
I/O7
I/O6

A7

NC

NC

NU

Vc

c

W

E

NC

I/O1

I/O2

Vss

NU

I/O3

I/O4

I/O5

14

15

16

17

18

19

20

4

3

2

1

32

31

30

29

28

27

26

25

24

23

22

21

5

6

7

8

9

10

11

12

13

DIP

PLCC

28
C

04A

• Pin 1 indicator on PLCC on top of package

28C

0

4

A

I/O0

I/O7

Input/Output

Buffers

Chip Enable/

Output Enable

Control Logic

CE

OE

Data Protection

Circuitry

A8

Y Gating

4K bit

Cell Matrix

X

Decoder

Y

Decoder

A0

Data

Poll

Auto Erase/Write

Timing

V

CC

V

SS

WE

L
a

t

c
h
e
s

Program Voltage

Generation

28C04A

4K (512 x 8) CMOS EEPROM

Obsolete Device

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28C04A

DS11126H-page  2

 2004 Microchip Technology Inc.

1.0

ELECTRICAL CHARACTERISTICS

1.1

MAXIMUM RATINGS*

V

CC

 and input voltages w.r.t. V

SS

....... -0.6V to + 6.25V

Voltage on OE w.r.t. V

SS

...................... -0.6V to +13.5V

Output Voltage w.r.t. V

SS

.................-0.6V to V

CC

+0.6V

Storage temperature ..........................-65°C to +125°C

Ambient temp. with power applied .......-50°C to +95°C

*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 operation listings of
this specification is not implied.  Exposure to maximum rating con-
ditions for extended periods may affect device reliability.

TABLE 1-1:

PIN FUNCTION TABLE

Name

Function

A0 - A8

Address Inputs

CE

Chip Enable

OE

Output Enable

WE

Write Enable

I/O0 - I/O7

Data Inputs/Outputs

V

CC

+5V Power Supply

V

SS

Ground

NC

No Connect; No Internal Connection

NU

Not Used; No External Connection is 
Allowed

TABLE 1-2:

READ/WRITE OPERATION DC CHARACTERISTICS 

V

CC

 = +5V 

±

10%

Commercial (C): Tamb =

   0°C to +70°C

Industrial       (I): Tamb =  -40°C to +85°C

Parameter

Status

Symbol

Min

Max

Units

Conditions

Input Voltages

Logic ‘1’
Logic ‘0’

V

IH

V

IL

2.0

-0.1

V

CC

+1

0.8

V
V

Input Leakage

I

LI

-10

10

µ

A

V

IN

 = -0.1V to V

CC

+1

Input Capacitance

C

IN

10

pF

V

IN

 = 0V; Tamb = 25°C;

f = 1 MHz

Output Voltages

Logic ‘1’
Logic ‘0’

V

OH

V

OL

2.4

0.45

V
V

I

OH

 = -400 

µ

A

I

OL

 = 2.1 mA

Output Leakage

I

LO

-10

10

µ

A

V

OUT

 = -0.1V 

TO

 V

CC

 + 0.1V

Output Capacitance

C

OUT

12

pF

V

IN

 = 0V; T

AMB

 = 25°C;

f = 1 MHz

Power Supply Current, Active

TTL input

I

CC

30

mA

f = 5 MHz (Note 1)
V

CC

 = 5.5V

Power Supply Current, Standby

TTL input
TTL input

CMOS input

I

CC

(

S

)

TTL

I

CC

(

S

)

TTL

I

CC

(

S

)

CMOS

2
3

100

mA
mA

µ

A

CE = V

IH

 (0°C to +70°C)

CE = V

IH

 (-40°C to +85°C)

CE = V

CC

-0.3 to V

CC

+1

OE  = V

CC

All inputs equal V

CC

 or V

SS

Note 1: AC power supply current above 5 MHz; 1 mA/MHz.

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 2004 Microchip Technology Inc.

DS11126H-page  3

28C04A

TABLE 1-3:

READ OPERATION AC CHARACTERISTICS

FIGURE 1-1:

READ WAVEFORMS

AC Testing Waveform:

V

IH

 = 2.4V; V

IL

 = 0.45V; V

OH

 = 2.0V; V

OL

 = 0.8V

Output Load:

1 TTL Load + 100 pF

Input Rise and Fall Times: 20 ns
Ambient Temperature:

Commercial (C): Tamb =

0°C to +70°C

Industrial 

(I):

Tamb =

-40°C to +85°C

Parameter

Sym

28C04A-15

28C04A-20

28C04A-25

Units

Conditions

Min

Max

Min

Max

Min

Max

Address to Output Delay

t

ACC

150

200

250

ns

OE = CE = V

IL

CE to Output Delay

t

CE

150

200

250

ns

OE = V

IL

OE to Output Delay

t

OE

70

80

100

ns

CE = V

IL

CE to OE High Output Float

t

OFF

0

50

0

55

0

70

ns

Output Hold from Address, CE 
or OE, whichever occurs first

t

OH

0

0

0

ns

Endurance

1M

1M

1M

cycles 25°C, Vcc = 

5.0V, Block 
Mode (Note)

Note: 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 BBS or website.

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28C04A

DS11126H-page  4

 2004 Microchip Technology Inc.

TABLE 1-4:

BYTE WRITE AC CHARACTERISTICS

FIGURE 1-2:

PROGRAMMING WAVEFORMS

AC Testing Waveform:

V

IH

 = 2.4V; V

IL

 = 0.45V; V

OH

 = 2.0V; V

OL

 = 0.8V

Output Load:

1 TTL Load + 100 pF

Input Rise/Fall Times:

20 nsec

Ambient Temperature:

Commercial  (C): Tamb= 0°C to 70°C
Industrial 

(I):

Tamb= -40°C to 85°C

Parameter

Symbol

Min

Max

Units

Remarks

Address Set-Up Time

t

AS

10

ns

Address Hold Time

t

AH

50

ns

Data Set-Up Time

t

DS

50

ns

Data Hold Time

t

DH

10

ns

Write Pulse Width

t

WPL

100

ns

Note 1

Write Pulse High Time

t

WPH

50

ns

OE Hold Time

t

OEH

10

ns

OE Set-Up Time

t

OES

10

ns

Data Valid Time

t

DV

1000

ns

Note 2

Write Cycle Time (28C04A)

t

WC

1

ms

0.5 ms typical

Write Cycle Time (28C04AF)

t

WC

200

µ

s

100 

µ

s typical

Note 1: A write cycle can be initiated be CE or WE going low, whichever occurs last.  The data is latched on the pos-

itive edge of CE or WE, whichever occurs first.

2: Data must be valid within 1000ns max. after a write cycle is initiated and must be stable at least until t

DH

 

after the positive edge of WE or CE, whichever occurs first.

t

AS

t

AH

t

WPL

t

DS

t

DH

t

OES

t

OEH

t

DV

Address

CE, WE

Data In

OE

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

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 2004 Microchip Technology Inc.

DS11126H-page  5

28C04A

FIGURE 1-3:

DATA POLLING WAVEFORMS

FIGURE 1-4:

CHIP CLEAR WAVEFORMS

Address Valid

Last Written

Address Valid

t

ACC

t

CE

t

WPL

t

WPH

t

DV

t

WC

t

OE

True Data Out

Data In

Valid

V

IH

V

IL

Data

OE

WE

CE

Address

I/O7 Out

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

H

V

IH

CE

OE

WE

t

S

t

H

t

W

t

S

=     = 1

µ

s

t

H

= 10ms

t

W

V

IH

V

IL

V

IH

V

IL

= 12.0V 

±

0.5V

V

H

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28C04A

DS11126H-page  6

 2004 Microchip Technology Inc.

2.0

DEVICE OPERATION

The Microchip Technology Inc. 28C04A has four basic
modes of operation—read, standby, write inhibit, and
byte write—as outlined in the following table.

2.1

Read Mode

The 28C04A has two control functions, both of which
must be logically satisfied in order to obtain data at the
outputs. Chip enable (CE) is the power control and
should be used for device selection. Output Enable
(OE) is the output control and is used to gate data to the
output pins independent of device selection. Assuming
that addresses are stable, address access time (t

ACC

)

is equal to the delay from CE  to  output  (t

CE

). Data is

available at the output tOE after the falling edge of OE,
assuming that CE has been low and addresses have
been stable for at least t

ACC

-t

OE

.

2.2

Standby Mode

The 28C04A is placed in the standby mode by applying
a high signal to the CE input. When in the standby
mode, the outputs are in a high impedance state, inde-
pendent of the OE input.

2.3

Data Protection

In order to ensure data integrity, especially during criti-
cal power-up and power-down transitions, the following
enhanced data protection circuits are incorporated:

First, an internal V

CC

 detect (3.3 volts typical) will inhibit

the initiation of non-volatile programming operation
when V

CC

 is less than the V

CC

 detect circuit trip. 

Second, there  is a WE filtering circuit that prevents WE
pulses of less than 10 ns  duration from initiating a write
cycle.

Third, holding WE or CE high or OE low, inhibits a write
cycle during power-on and power-off (V

CC

).

Operation 

Mode

CE

IE

WE

I/O

Read

L

L

H

D

OUT

Standby

H

X

X

High Z

Write Inhibit

H

X

X

High Z

Write Inhibit

X

L

X

High Z

Write Inhibit

X

X

H

High Z

Byte Write

L

H

L

D

IN

Byte Clear

Automatic Before Each “Write”

X = Any TTL level.

2.4

Write Mode

The 28C04A has a write cycle similar to that of a Static
RAM. The write cycle is completely self-timed and initi-
ated by a low going pulse on the WE pin. On the falling
edge of WE, the address information is latched. On ris-
ing edge, the data and the control pins (CE and OE) are
latched. 

2.5

Data Polling

The 28C04A features Data polling to signal the comple-
tion of a byte write cycle. During a write cycle, an
attempted read of the last byte written results in the
data complement of I/O7 (I/O0 to I/O6 are indetermin-
able). After completion of the write cycle, true data is
available. Data polling allows a simple read/compare
operation to determine the status of the chip eliminating
the need for external hardware.

2.6

Chip Clear

All data may be cleared to 1's in a chip clear cycle by
raising OE to 12 volts and bringing the WE and CE low.
This procedure clears all data.

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background image

28C04A

28C04A 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.

Package:

L = Plastic Leaded Chip Carrier (PLCC)

P = Plastic DIP (600mill)

Temperature

Blank = 0

°

C to +70

°

Range:

I

= -40

°

C to +85

°

C

Access Time:

15

150 ns

20

200 ns

25

250 ns

Shipping:

Blank

Tube

T

Tape and Reel “L” only

Option:

Blank = twc = 1ms

F = twc = 200 

µ

s

Device:

28C04A

512 x 8 CMOS EEPROM 

28C04A

F

T

15

/P

 2004 Microchip Technology Inc.

DS11126H-page  7

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background image

28C04A

DS11126H-page  8

 2004 Microchip Technology Inc.

NOTES:

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 2004 Microchip Technology Inc.

DS11126H-page 9

Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical
components in life support systems is not authorized except
with express written approval by Microchip. No licenses are
conveyed, implicitly or otherwise, under any intellectual
property rights.

Trademarks

The Microchip name and logo, the Microchip logo, Accuron, 
dsPIC, K

EE

L

OQ

, micro

ID

, MPLAB, PIC, PICmicro, PICSTART, 

PRO MATE, PowerSmart, rfPIC, and SmartShunt are 
registered trademarks of Microchip Technology Incorporated 
in the U.S.A. and other countries.

AmpLab, FilterLab, MXDEV, MXLAB, PICMASTER, SEEVAL, 
SmartSensor and The Embedded Control Solutions Company 
are registered trademarks of Microchip Technology 
Incorporated in the U.S.A.

Analog-for-the-Digital Age, Application Maestro, dsPICDEM, 
dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, 
FanSense, FlexROM, fuzzyLAB, In-Circuit Serial 
Programming, ICSP, ICEPIC, Migratable Memory, MPASM, 
MPLIB, MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net, 
PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, 
PowerTool, rfLAB, rfPICDEM, Select Mode, Smart Serial, 
SmartTel and Total Endurance are trademarks of Microchip 
Technology Incorporated in the U.S.A. and other countries.

SQTP is a service mark of Microchip Technology Incorporated 
in the U.S.A.

All other trademarks mentioned herein are property of their 
respective companies.

© 2004, Microchip Technology Incorporated, Printed in the 
U.S.A., All Rights Reserved.

 Printed on recycled paper.

Note the following details of the code protection feature on Microchip devices:

Microchip products meet the specification contained in their particular Microchip Data Sheet.

Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the 
intended manner and under normal conditions.

There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our 
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data 
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

Microchip is willing to work with the customer who is concerned about the integrity of their code.

Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not 
mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Microchip received ISO/TS-16949:2002 quality system certification for 
its worldwide headquarters, design and wafer fabrication facilities in 
Chandler and Tempe, Arizona and Mountain View, California in 
October 2003. The Company’s quality system processes and 
procedures are for its PICmicro

®

 

8-bit MCUs, K

EE

L

OQ

®

 

code hopping 

devices, Serial EEPROMs, microperipherals, nonvolatile memory and 
analog products. In addition, Microchip’s quality system for the design 
and manufacture of development systems is ISO 9001:2000 certified.

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background image

 2004 Microchip Technology Inc.

AMERICAS

Corporate Office

2355 West Chandler Blvd.
Chandler, AZ  85224-6199
Tel:  480-792-7200  
Fax:  480-792-7277
Technical Support: 480-792-7627
Web Address: www.microchip.com

Atlanta

3780 Mansell Road, Suite 130
Alpharetta, GA  30022
Tel: 770-640-0034  
Fax: 770-640-0307

Boston

2 Lan Drive, Suite 120
Westford, MA  01886
Tel: 978-692-3848 
Fax: 978-692-3821

Chicago

333 Pierce Road, Suite 180
Itasca, IL  60143
Tel: 630-285-0071 
Fax: 630-285-0075

Dallas

16200 Addison Road, Suite 255
Addison Plaza
Addison, TX 75001
Tel: 972-818-7423  
Fax: 972-818-2924

Detroit

Tri-Atria Office Building 
32255 Northwestern Highway, Suite 190
Farmington Hills, MI  48334
Tel: 248-538-2250
Fax: 248-538-2260

Kokomo

2767 S. Albright Road 
Kokomo, IN  46902
Tel: 765-864-8360
Fax: 765-864-8387

Los Angeles

25950 Acero St., Suite 200
Mission Viejo, CA  92691
Tel: 949-462-9523  
Fax: 949-462-9608

San Jose

1300 Terra Bella Avenue
Mountain View, CA 94043
Tel: 650-215-1444
Fax: 650-961-0286

Toronto

6285 Northam Drive, Suite 108
Mississauga, Ontario L4V 1X5, Canada
Tel: 905-673-0699  
Fax:  905-673-6509

ASIA/PACIFIC

Australia

Microchip Technology Australia Pty Ltd
Unit 32 41 Rawson Street
Epping 2121, NSW
Sydney, Australia
Tel: 61-2-9868-6733 
Fax: 61-2-9868-6755

China - Beijing

Unit 706B
Wan Tai Bei Hai Bldg.
No. 6 Chaoyangmen Bei Str. 
Beijing, 100027, China
Tel: 86-10-85282100 
Fax: 86-10-85282104

China - Chengdu

Rm. 2401-2402, 24th Floor, 
Ming Xing Financial Tower
No. 88 TIDU Street
Chengdu 610016, China
Tel: 86-28-86766200  
Fax: 86-28-86766599

China - Fuzhou

Unit 28F, World Trade Plaza
No. 71 Wusi Road
Fuzhou 350001, China
Tel: 86-591-7503506  
Fax: 86-591-7503521

China - Hong Kong SAR

Unit 901-6, Tower 2, Metroplaza
223 Hing Fong Road
Kwai Fong, N.T., Hong Kong
Tel: 852-2401-1200  
Fax: 852-2401-3431

China - Shanghai

Room 701, Bldg. B
Far East International Plaza
No. 317 Xian Xia Road
Shanghai, 200051
Tel: 86-21-6275-5700  
Fax: 86-21-6275-5060

China - Shenzhen

Rm. 1812, 18/F, Building A, United Plaza
No. 5022 Binhe Road, Futian District
Shenzhen 518033, China
Tel: 86-755-82901380 
Fax: 86-755-8295-1393

China - Shunde

Room 401, Hongjian Building, No. 2 
Fengxiangnan Road, Ronggui Town, Shunde
District, Foshan City, Guangdong 528303, China
Tel: 86-757-28395507  Fax: 86-757-28395571

China - Qingdao

Rm. B505A, Fullhope Plaza,
No. 12 Hong Kong Central Rd.
Qingdao 266071, China
Tel: 86-532-5027355  Fax: 86-532-5027205

India

Divyasree Chambers
1 Floor, Wing A (A3/A4)
No. 11, O’Shaugnessey Road
Bangalore, 560 025, India
Tel: 91-80-22290061 Fax: 91-80-22290062

Japan

Yusen Shin Yokohama Building 10F
3-17-2, Shin Yokohama, Kohoku-ku,
Yokohama, Kanagawa, 222-0033, Japan
Tel: 81-45-471- 6166  Fax: 81-45-471-6122

Korea

168-1, Youngbo Bldg. 3 Floor
Samsung-Dong, Kangnam-Ku
Seoul, Korea 135-882
Tel: 82-2-554-7200  Fax: 82-2-558-5932 or 
82-2-558-5934

Singapore

200 Middle Road
#07-02 Prime Centre
Singapore, 188980
Tel:  65-6334-8870  Fax: 65-6334-8850

Taiwan

Kaohsiung Branch
30F - 1 No. 8
Min Chuan 2nd Road
Kaohsiung 806, Taiwan
Tel: 886-7-536-4816
Fax: 886-7-536-4817

Taiwan

Taiwan Branch
11F-3, No. 207
Tung Hua North Road
Taipei, 105, Taiwan
Tel: 886-2-2717-7175  Fax: 886-2-2545-0139

Taiwan

Taiwan Branch
13F-3, No. 295, Sec. 2, Kung Fu Road
Hsinchu City 300, Taiwan
Tel: 886-3-572-9526
Fax: 886-3-572-6459

EUROPE

Austria

Durisolstrasse 2
A-4600 Wels
Austria
Tel: 43-7242-2244-399
Fax: 43-7242-2244-393

Denmark

Regus Business Centre
Lautrup hoj 1-3
Ballerup DK-2750 Denmark
Tel: 45-4420-9895 Fax: 45-4420-9910

France

Parc d’Activite du Moulin de Massy
43 Rue du Saule Trapu
Batiment A - ler Etage
91300 Massy, France
Tel: 33-1-69-53-63-20  
Fax: 33-1-69-30-90-79

Germany

Steinheilstrasse 10
D-85737 Ismaning, Germany
Tel: 49-89-627-144-0 
Fax: 49-89-627-144-44

Italy

Via Salvatore Quasimodo, 12
20025 Legnano (MI)
Milan, Italy 
Tel: 39-0331-742611  
Fax: 39-0331-466781

Netherlands

Waegenburghtplein 4
NL-5152 JR, Drunen, Netherlands
Tel: 31-416-690399 
Fax: 31-416-690340

United Kingdom

505 Eskdale Road
Winnersh Triangle
Wokingham 
Berkshire, England RG41 5TU
Tel: 44-118-921-5869
Fax: 44-118-921-5820

07/12/04

W

ORLDWIDE

 S

ALES

 

AND

 S

ERVICE

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 2004 Microchip Technology Inc.

DS11126H-page  1

FEATURES

• Fast Read Access Time—150 ns 

• CMOS Technology for Low Power Dissipation

- 30 mA Active

- 100 

µ

A Standby

• Fast Byte Write Time—200 

µ

s or 1 ms 

• Data Retention >200 years

• Endurance - Minimum 10

4

  Erase/Write Cycles

- Automatic Write Operation

- Internal Control Timer

- Auto-Clear Before Write Operation

- On-Chip Address and Data Latches

• Data Polling

• Chip Clear Operation

• Enhanced Data Protection

- V

CC

 Detector

- Pulse Filter

- Write Inhibit

• 5-Volt-Only Operation

• Organized 512x8 JEDEC standard pinout

- 24-pin Dual-In-Line Package

- 32-pin PLCC Package

• Available for Extended Temperature Ranges:

- Commercial: 0°C to +70°C

- Industrial: -40°C to +85°C

DESCRIPTION

The Microchip Technology Inc. 28C04A is a CMOS 4K
non-volatile electrically Erasable and Programmable
Read Only Memory (EEPROM). The 28C04A is
accessed like a static RAM for the read or write cycles
without the need of external components. During a
“byte write”, the address and data are latched inter-
nally, freeing the microprocessor address and data bus
for other operations. Following the initiation of write
cycle, the device will go to a busy state and automati-
cally clear and write the latched data using an internal
control timer. To determine when a write cycle is com-
plete, the 28C04A uses Data polling. Data polling
allows the user to read the location last written to when
the write operation is complete. CMOS design and pro-
cessing enables this part to be used in systems where
reduced power consumption and reliability are
required. A complete family of packages is offered to
provide the utmost flexibility in applications.

PACKAGE TYPES

BLOCK DIAGRAM

• 1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

A7

A6

A5

A4

A3

A2

A1

A0

I/O0

I/O1

I/O2

V   

Vcc

A8

NC

WE

OE

NC

CE

I/O7

I/O6

I/O5

I/O4

I/O3

SS

A6
A5
A4
A3
A2
A1
A0

NC

I/O0

A8
NC
NC
NC
OE
NC
CE
I/O7
I/O6

A7

NC

NC

NU

Vc

c

W

E

NC

I/O1

I/O2

Vss

NU

I/O3

I/O4

I/O5

14

15

16

17

18

19

20

4

3

2

1

32

31

30

29

28

27

26

25

24

23

22

21

5

6

7

8

9

10

11

12

13

DIP

PLCC

28
C

04A

• Pin 1 indicator on PLCC on top of package

28C

0

4

A

I/O0

I/O7

Input/Output

Buffers

Chip Enable/

Output Enable

Control Logic

CE

OE

Data Protection

Circuitry

A8

Y Gating

4K bit

Cell Matrix

X

Decoder

Y

Decoder

A0

Data

Poll

Auto Erase/Write

Timing

V

CC

V

SS

WE

L
a

t

c
h
e
s

Program Voltage

Generation

28C04A

4K (512 x 8) CMOS EEPROM

Obsolete Device

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28C04A

DS11126H-page  2

 2004 Microchip Technology Inc.

1.0

ELECTRICAL CHARACTERISTICS

1.1

MAXIMUM RATINGS*

V

CC

 and input voltages w.r.t. V

SS

....... -0.6V to + 6.25V

Voltage on OE w.r.t. V

SS

...................... -0.6V to +13.5V

Output Voltage w.r.t. V

SS

.................-0.6V to V

CC

+0.6V

Storage temperature ..........................-65°C to +125°C

Ambient temp. with power applied .......-50°C to +95°C

*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 operation listings of
this specification is not implied.  Exposure to maximum rating con-
ditions for extended periods may affect device reliability.

TABLE 1-1:

PIN FUNCTION TABLE

Name

Function

A0 - A8

Address Inputs

CE

Chip Enable

OE

Output Enable

WE

Write Enable

I/O0 - I/O7

Data Inputs/Outputs

V

CC

+5V Power Supply

V

SS

Ground

NC

No Connect; No Internal Connection

NU

Not Used; No External Connection is 
Allowed

TABLE 1-2:

READ/WRITE OPERATION DC CHARACTERISTICS 

V

CC

 = +5V 

±

10%

Commercial (C): Tamb =

   0°C to +70°C

Industrial       (I): Tamb =  -40°C to +85°C

Parameter

Status

Symbol

Min

Max

Units

Conditions

Input Voltages

Logic ‘1’
Logic ‘0’

V

IH

V

IL

2.0

-0.1

V

CC

+1

0.8

V
V

Input Leakage

I

LI

-10

10

µ

A

V

IN

 = -0.1V to V

CC

+1

Input Capacitance

C

IN

10

pF

V

IN

 = 0V; Tamb = 25°C;

f = 1 MHz

Output Voltages

Logic ‘1’
Logic ‘0’

V

OH

V

OL

2.4

0.45

V
V

I

OH

 = -400 

µ

A

I

OL

 = 2.1 mA

Output Leakage

I

LO

-10

10

µ

A

V

OUT

 = -0.1V 

TO

 V

CC

 + 0.1V

Output Capacitance

C

OUT

12

pF

V

IN

 = 0V; T

AMB

 = 25°C;

f = 1 MHz

Power Supply Current, Active

TTL input

I

CC

30

mA

f = 5 MHz (Note 1)
V

CC

 = 5.5V

Power Supply Current, Standby

TTL input
TTL input

CMOS input

I

CC

(

S

)

TTL

I

CC

(

S

)

TTL

I

CC

(

S

)

CMOS

2
3

100

mA
mA

µ

A

CE = V

IH

 (0°C to +70°C)

CE = V

IH

 (-40°C to +85°C)

CE = V

CC

-0.3 to V

CC

+1

OE  = V

CC

All inputs equal V

CC

 or V

SS

Note 1: AC power supply current above 5 MHz; 1 mA/MHz.

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 2004 Microchip Technology Inc.

DS11126H-page  3

28C04A

TABLE 1-3:

READ OPERATION AC CHARACTERISTICS

FIGURE 1-1:

READ WAVEFORMS

AC Testing Waveform:

V

IH

 = 2.4V; V

IL

 = 0.45V; V

OH

 = 2.0V; V

OL

 = 0.8V

Output Load:

1 TTL Load + 100 pF

Input Rise and Fall Times: 20 ns
Ambient Temperature:

Commercial (C): Tamb =

0°C to +70°C

Industrial 

(I):

Tamb =

-40°C to +85°C

Parameter

Sym

28C04A-15

28C04A-20

28C04A-25

Units

Conditions

Min

Max

Min

Max

Min

Max

Address to Output Delay

t

ACC

150

200

250

ns

OE = CE = V

IL

CE to Output Delay

t

CE

150

200

250

ns

OE = V

IL

OE to Output Delay

t

OE

70

80

100

ns

CE = V

IL

CE to OE High Output Float

t

OFF

0

50

0

55

0

70

ns

Output Hold from Address, CE 
or OE, whichever occurs first

t

OH

0

0

0

ns

Endurance

1M

1M

1M

cycles 25°C, Vcc = 

5.0V, Block 
Mode (Note)

Note: 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 BBS or website.

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background image

28C04A

DS11126H-page  4

 2004 Microchip Technology Inc.

TABLE 1-4:

BYTE WRITE AC CHARACTERISTICS

FIGURE 1-2:

PROGRAMMING WAVEFORMS

AC Testing Waveform:

V

IH

 = 2.4V; V

IL

 = 0.45V; V

OH

 = 2.0V; V

OL

 = 0.8V

Output Load:

1 TTL Load + 100 pF

Input Rise/Fall Times:

20 nsec

Ambient Temperature:

Commercial  (C): Tamb= 0°C to 70°C
Industrial 

(I):

Tamb= -40°C to 85°C

Parameter

Symbol

Min

Max

Units

Remarks

Address Set-Up Time

t

AS

10

ns

Address Hold Time

t

AH

50

ns

Data Set-Up Time

t

DS

50

ns

Data Hold Time

t

DH

10

ns

Write Pulse Width

t

WPL

100

ns

Note 1

Write Pulse High Time

t

WPH

50

ns

OE Hold Time

t

OEH

10

ns

OE Set-Up Time

t

OES

10

ns

Data Valid Time

t

DV

1000

ns

Note 2

Write Cycle Time (28C04A)

t

WC

1

ms

0.5 ms typical

Write Cycle Time (28C04AF)

t

WC

200

µ

s

100 

µ

s typical

Note 1: A write cycle can be initiated be CE or WE going low, whichever occurs last.  The data is latched on the pos-

itive edge of CE or WE, whichever occurs first.

2: Data must be valid within 1000ns max. after a write cycle is initiated and must be stable at least until t

DH

 

after the positive edge of WE or CE, whichever occurs first.

t

AS

t

AH

t

WPL

t

DS

t

DH

t

OES

t

OEH

t

DV

Address

CE, WE

Data In

OE

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

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 2004 Microchip Technology Inc.

DS11126H-page  5

28C04A

FIGURE 1-3:

DATA POLLING WAVEFORMS

FIGURE 1-4:

CHIP CLEAR WAVEFORMS

Address Valid

Last Written

Address Valid

t

ACC

t

CE

t

WPL

t

WPH

t

DV

t

WC

t

OE

True Data Out

Data In

Valid

V

IH

V

IL

Data

OE

WE

CE

Address

I/O7 Out

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

H

V

IH

CE

OE

WE

t

S

t

H

t

W

t

S

=     = 1

µ

s

t

H

= 10ms

t

W

V

IH

V

IL

V

IH

V

IL

= 12.0V 

±

0.5V

V

H

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28C04A

DS11126H-page  6

 2004 Microchip Technology Inc.

2.0

DEVICE OPERATION

The Microchip Technology Inc. 28C04A has four basic
modes of operation—read, standby, write inhibit, and
byte write—as outlined in the following table.

2.1

Read Mode

The 28C04A has two control functions, both of which
must be logically satisfied in order to obtain data at the
outputs. Chip enable (CE) is the power control and
should be used for device selection. Output Enable
(OE) is the output control and is used to gate data to the
output pins independent of device selection. Assuming
that addresses are stable, address access time (t

ACC

)

is equal to the delay from CE  to  output  (t

CE

). Data is

available at the output tOE after the falling edge of OE,
assuming that CE has been low and addresses have
been stable for at least t

ACC

-t

OE

.

2.2

Standby Mode

The 28C04A is placed in the standby mode by applying
a high signal to the CE input. When in the standby
mode, the outputs are in a high impedance state, inde-
pendent of the OE input.

2.3

Data Protection

In order to ensure data integrity, especially during criti-
cal power-up and power-down transitions, the following
enhanced data protection circuits are incorporated:

First, an internal V

CC

 detect (3.3 volts typical) will inhibit

the initiation of non-volatile programming operation
when V

CC

 is less than the V

CC

 detect circuit trip. 

Second, there  is a WE filtering circuit that prevents WE
pulses of less than 10 ns  duration from initiating a write
cycle.

Third, holding WE or CE high or OE low, inhibits a write
cycle during power-on and power-off (V

CC

).

Operation 

Mode

CE

IE

WE

I/O

Read

L

L

H

D

OUT

Standby

H

X

X

High Z

Write Inhibit

H

X

X

High Z

Write Inhibit

X

L

X

High Z

Write Inhibit

X

X

H

High Z

Byte Write

L

H

L

D

IN

Byte Clear

Automatic Before Each “Write”

X = Any TTL level.

2.4

Write Mode

The 28C04A has a write cycle similar to that of a Static
RAM. The write cycle is completely self-timed and initi-
ated by a low going pulse on the WE pin. On the falling
edge of WE, the address information is latched. On ris-
ing edge, the data and the control pins (CE and OE) are
latched. 

2.5

Data Polling

The 28C04A features Data polling to signal the comple-
tion of a byte write cycle. During a write cycle, an
attempted read of the last byte written results in the
data complement of I/O7 (I/O0 to I/O6 are indetermin-
able). After completion of the write cycle, true data is
available. Data polling allows a simple read/compare
operation to determine the status of the chip eliminating
the need for external hardware.

2.6

Chip Clear

All data may be cleared to 1's in a chip clear cycle by
raising OE to 12 volts and bringing the WE and CE low.
This procedure clears all data.

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28C04A

28C04A 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.

Package:

L = Plastic Leaded Chip Carrier (PLCC)

P = Plastic DIP (600mill)

Temperature

Blank = 0

°

C to +70

°

Range:

I

= -40

°

C to +85

°

C

Access Time:

15

150 ns

20

200 ns

25

250 ns

Shipping:

Blank

Tube

T

Tape and Reel “L” only

Option:

Blank = twc = 1ms

F = twc = 200 

µ

s

Device:

28C04A

512 x 8 CMOS EEPROM 

28C04A

F

T

15

/P

 2004 Microchip Technology Inc.

DS11126H-page  7

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28C04A

DS11126H-page  8

 2004 Microchip Technology Inc.

NOTES:

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 2004 Microchip Technology Inc.

DS11126H-page 9

Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical
components in life support systems is not authorized except
with express written approval by Microchip. No licenses are
conveyed, implicitly or otherwise, under any intellectual
property rights.

Trademarks

The Microchip name and logo, the Microchip logo, Accuron, 
dsPIC, K

EE

L

OQ

, micro

ID

, MPLAB, PIC, PICmicro, PICSTART, 

PRO MATE, PowerSmart, rfPIC, and SmartShunt are 
registered trademarks of Microchip Technology Incorporated 
in the U.S.A. and other countries.

AmpLab, FilterLab, MXDEV, MXLAB, PICMASTER, SEEVAL, 
SmartSensor and The Embedded Control Solutions Company 
are registered trademarks of Microchip Technology 
Incorporated in the U.S.A.

Analog-for-the-Digital Age, Application Maestro, dsPICDEM, 
dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, 
FanSense, FlexROM, fuzzyLAB, In-Circuit Serial 
Programming, ICSP, ICEPIC, Migratable Memory, MPASM, 
MPLIB, MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net, 
PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, 
PowerTool, rfLAB, rfPICDEM, Select Mode, Smart Serial, 
SmartTel and Total Endurance are trademarks of Microchip 
Technology Incorporated in the U.S.A. and other countries.

SQTP is a service mark of Microchip Technology Incorporated 
in the U.S.A.

All other trademarks mentioned herein are property of their 
respective companies.

© 2004, Microchip Technology Incorporated, Printed in the 
U.S.A., All Rights Reserved.

 Printed on recycled paper.

Note the following details of the code protection feature on Microchip devices:

Microchip products meet the specification contained in their particular Microchip Data Sheet.

Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the 
intended manner and under normal conditions.

There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our 
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data 
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

Microchip is willing to work with the customer who is concerned about the integrity of their code.

Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not 
mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Microchip received ISO/TS-16949:2002 quality system certification for 
its worldwide headquarters, design and wafer fabrication facilities in 
Chandler and Tempe, Arizona and Mountain View, California in 
October 2003. The Company’s quality system processes and 
procedures are for its PICmicro

®

 

8-bit MCUs, K

EE

L

OQ

®

 

code hopping 

devices, Serial EEPROMs, microperipherals, nonvolatile memory and 
analog products. In addition, Microchip’s quality system for the design 
and manufacture of development systems is ISO 9001:2000 certified.

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background image

 2004 Microchip Technology Inc.

AMERICAS

Corporate Office

2355 West Chandler Blvd.
Chandler, AZ  85224-6199
Tel:  480-792-7200  
Fax:  480-792-7277
Technical Support: 480-792-7627
Web Address: www.microchip.com

Atlanta

3780 Mansell Road, Suite 130
Alpharetta, GA  30022
Tel: 770-640-0034  
Fax: 770-640-0307

Boston

2 Lan Drive, Suite 120
Westford, MA  01886
Tel: 978-692-3848 
Fax: 978-692-3821

Chicago

333 Pierce Road, Suite 180
Itasca, IL  60143
Tel: 630-285-0071 
Fax: 630-285-0075

Dallas

16200 Addison Road, Suite 255
Addison Plaza
Addison, TX 75001
Tel: 972-818-7423  
Fax: 972-818-2924

Detroit

Tri-Atria Office Building 
32255 Northwestern Highway, Suite 190
Farmington Hills, MI  48334
Tel: 248-538-2250
Fax: 248-538-2260

Kokomo

2767 S. Albright Road 
Kokomo, IN  46902
Tel: 765-864-8360
Fax: 765-864-8387

Los Angeles

25950 Acero St., Suite 200
Mission Viejo, CA  92691
Tel: 949-462-9523  
Fax: 949-462-9608

San Jose

1300 Terra Bella Avenue
Mountain View, CA 94043
Tel: 650-215-1444
Fax: 650-961-0286

Toronto

6285 Northam Drive, Suite 108
Mississauga, Ontario L4V 1X5, Canada
Tel: 905-673-0699  
Fax:  905-673-6509

ASIA/PACIFIC

Australia

Microchip Technology Australia Pty Ltd
Unit 32 41 Rawson Street
Epping 2121, NSW
Sydney, Australia
Tel: 61-2-9868-6733 
Fax: 61-2-9868-6755

China - Beijing

Unit 706B
Wan Tai Bei Hai Bldg.
No. 6 Chaoyangmen Bei Str. 
Beijing, 100027, China
Tel: 86-10-85282100 
Fax: 86-10-85282104

China - Chengdu

Rm. 2401-2402, 24th Floor, 
Ming Xing Financial Tower
No. 88 TIDU Street
Chengdu 610016, China
Tel: 86-28-86766200  
Fax: 86-28-86766599

China - Fuzhou

Unit 28F, World Trade Plaza
No. 71 Wusi Road
Fuzhou 350001, China
Tel: 86-591-7503506  
Fax: 86-591-7503521

China - Hong Kong SAR

Unit 901-6, Tower 2, Metroplaza
223 Hing Fong Road
Kwai Fong, N.T., Hong Kong
Tel: 852-2401-1200  
Fax: 852-2401-3431

China - Shanghai

Room 701, Bldg. B
Far East International Plaza
No. 317 Xian Xia Road
Shanghai, 200051
Tel: 86-21-6275-5700  
Fax: 86-21-6275-5060

China - Shenzhen

Rm. 1812, 18/F, Building A, United Plaza
No. 5022 Binhe Road, Futian District
Shenzhen 518033, China
Tel: 86-755-82901380 
Fax: 86-755-8295-1393

China - Shunde

Room 401, Hongjian Building, No. 2 
Fengxiangnan Road, Ronggui Town, Shunde
District, Foshan City, Guangdong 528303, China
Tel: 86-757-28395507  Fax: 86-757-28395571

China - Qingdao

Rm. B505A, Fullhope Plaza,
No. 12 Hong Kong Central Rd.
Qingdao 266071, China
Tel: 86-532-5027355  Fax: 86-532-5027205

India

Divyasree Chambers
1 Floor, Wing A (A3/A4)
No. 11, O’Shaugnessey Road
Bangalore, 560 025, India
Tel: 91-80-22290061 Fax: 91-80-22290062

Japan

Yusen Shin Yokohama Building 10F
3-17-2, Shin Yokohama, Kohoku-ku,
Yokohama, Kanagawa, 222-0033, Japan
Tel: 81-45-471- 6166  Fax: 81-45-471-6122

Korea

168-1, Youngbo Bldg. 3 Floor
Samsung-Dong, Kangnam-Ku
Seoul, Korea 135-882
Tel: 82-2-554-7200  Fax: 82-2-558-5932 or 
82-2-558-5934

Singapore

200 Middle Road
#07-02 Prime Centre
Singapore, 188980
Tel:  65-6334-8870  Fax: 65-6334-8850

Taiwan

Kaohsiung Branch
30F - 1 No. 8
Min Chuan 2nd Road
Kaohsiung 806, Taiwan
Tel: 886-7-536-4816
Fax: 886-7-536-4817

Taiwan

Taiwan Branch
11F-3, No. 207
Tung Hua North Road
Taipei, 105, Taiwan
Tel: 886-2-2717-7175  Fax: 886-2-2545-0139

Taiwan

Taiwan Branch
13F-3, No. 295, Sec. 2, Kung Fu Road
Hsinchu City 300, Taiwan
Tel: 886-3-572-9526
Fax: 886-3-572-6459

EUROPE

Austria

Durisolstrasse 2
A-4600 Wels
Austria
Tel: 43-7242-2244-399
Fax: 43-7242-2244-393

Denmark

Regus Business Centre
Lautrup hoj 1-3
Ballerup DK-2750 Denmark
Tel: 45-4420-9895 Fax: 45-4420-9910

France

Parc d’Activite du Moulin de Massy
43 Rue du Saule Trapu
Batiment A - ler Etage
91300 Massy, France
Tel: 33-1-69-53-63-20  
Fax: 33-1-69-30-90-79

Germany

Steinheilstrasse 10
D-85737 Ismaning, Germany
Tel: 49-89-627-144-0 
Fax: 49-89-627-144-44

Italy

Via Salvatore Quasimodo, 12
20025 Legnano (MI)
Milan, Italy 
Tel: 39-0331-742611  
Fax: 39-0331-466781

Netherlands

Waegenburghtplein 4
NL-5152 JR, Drunen, Netherlands
Tel: 31-416-690399 
Fax: 31-416-690340

United Kingdom

505 Eskdale Road
Winnersh Triangle
Wokingham 
Berkshire, England RG41 5TU
Tel: 44-118-921-5869
Fax: 44-118-921-5820

07/12/04

W

ORLDWIDE

 S

ALES

 

AND

 S

ERVICE

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 2004 Microchip Technology Inc.

DS11126H-page  1

FEATURES

• Fast Read Access Time—150 ns 

• CMOS Technology for Low Power Dissipation

- 30 mA Active

- 100 

µ

A Standby

• Fast Byte Write Time—200 

µ

s or 1 ms 

• Data Retention >200 years

• Endurance - Minimum 10

4

  Erase/Write Cycles

- Automatic Write Operation

- Internal Control Timer

- Auto-Clear Before Write Operation

- On-Chip Address and Data Latches

• Data Polling

• Chip Clear Operation

• Enhanced Data Protection

- V

CC

 Detector

- Pulse Filter

- Write Inhibit

• 5-Volt-Only Operation

• Organized 512x8 JEDEC standard pinout

- 24-pin Dual-In-Line Package

- 32-pin PLCC Package

• Available for Extended Temperature Ranges:

- Commercial: 0°C to +70°C

- Industrial: -40°C to +85°C

DESCRIPTION

The Microchip Technology Inc. 28C04A is a CMOS 4K
non-volatile electrically Erasable and Programmable
Read Only Memory (EEPROM). The 28C04A is
accessed like a static RAM for the read or write cycles
without the need of external components. During a
“byte write”, the address and data are latched inter-
nally, freeing the microprocessor address and data bus
for other operations. Following the initiation of write
cycle, the device will go to a busy state and automati-
cally clear and write the latched data using an internal
control timer. To determine when a write cycle is com-
plete, the 28C04A uses Data polling. Data polling
allows the user to read the location last written to when
the write operation is complete. CMOS design and pro-
cessing enables this part to be used in systems where
reduced power consumption and reliability are
required. A complete family of packages is offered to
provide the utmost flexibility in applications.

PACKAGE TYPES

BLOCK DIAGRAM

• 1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

A7

A6

A5

A4

A3

A2

A1

A0

I/O0

I/O1

I/O2

V   

Vcc

A8

NC

WE

OE

NC

CE

I/O7

I/O6

I/O5

I/O4

I/O3

SS

A6
A5
A4
A3
A2
A1
A0

NC

I/O0

A8
NC
NC
NC
OE
NC
CE
I/O7
I/O6

A7

NC

NC

NU

Vc

c

W

E

NC

I/O1

I/O2

Vss

NU

I/O3

I/O4

I/O5

14

15

16

17

18

19

20

4

3

2

1

32

31

30

29

28

27

26

25

24

23

22

21

5

6

7

8

9

10

11

12

13

DIP

PLCC

28
C

04A

• Pin 1 indicator on PLCC on top of package

28C

0

4

A

I/O0

I/O7

Input/Output

Buffers

Chip Enable/

Output Enable

Control Logic

CE

OE

Data Protection

Circuitry

A8

Y Gating

4K bit

Cell Matrix

X

Decoder

Y

Decoder

A0

Data

Poll

Auto Erase/Write

Timing

V

CC

V

SS

WE

L
a

t

c
h
e
s

Program Voltage

Generation

28C04A

4K (512 x 8) CMOS EEPROM

Obsolete Device

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28C04A

DS11126H-page  2

 2004 Microchip Technology Inc.

1.0

ELECTRICAL CHARACTERISTICS

1.1

MAXIMUM RATINGS*

V

CC

 and input voltages w.r.t. V

SS

....... -0.6V to + 6.25V

Voltage on OE w.r.t. V

SS

...................... -0.6V to +13.5V

Output Voltage w.r.t. V

SS

.................-0.6V to V

CC

+0.6V

Storage temperature ..........................-65°C to +125°C

Ambient temp. with power applied .......-50°C to +95°C

*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 operation listings of
this specification is not implied.  Exposure to maximum rating con-
ditions for extended periods may affect device reliability.

TABLE 1-1:

PIN FUNCTION TABLE

Name

Function

A0 - A8

Address Inputs

CE

Chip Enable

OE

Output Enable

WE

Write Enable

I/O0 - I/O7

Data Inputs/Outputs

V

CC

+5V Power Supply

V

SS

Ground

NC

No Connect; No Internal Connection

NU

Not Used; No External Connection is 
Allowed

TABLE 1-2:

READ/WRITE OPERATION DC CHARACTERISTICS 

V

CC

 = +5V 

±

10%

Commercial (C): Tamb =

   0°C to +70°C

Industrial       (I): Tamb =  -40°C to +85°C

Parameter

Status

Symbol

Min

Max

Units

Conditions

Input Voltages

Logic ‘1’
Logic ‘0’

V

IH

V

IL

2.0

-0.1

V

CC

+1

0.8

V
V

Input Leakage

I

LI

-10

10

µ

A

V

IN

 = -0.1V to V

CC

+1

Input Capacitance

C

IN

10

pF

V

IN

 = 0V; Tamb = 25°C;

f = 1 MHz

Output Voltages

Logic ‘1’
Logic ‘0’

V

OH

V

OL

2.4

0.45

V
V

I

OH

 = -400 

µ

A

I

OL

 = 2.1 mA

Output Leakage

I

LO

-10

10

µ

A

V

OUT

 = -0.1V 

TO

 V

CC

 + 0.1V

Output Capacitance

C

OUT

12

pF

V

IN

 = 0V; T

AMB

 = 25°C;

f = 1 MHz

Power Supply Current, Active

TTL input

I

CC

30

mA

f = 5 MHz (Note 1)
V

CC

 = 5.5V

Power Supply Current, Standby

TTL input
TTL input

CMOS input

I

CC

(

S

)

TTL

I

CC

(

S

)

TTL

I

CC

(

S

)

CMOS

2
3

100

mA
mA

µ

A

CE = V

IH

 (0°C to +70°C)

CE = V

IH

 (-40°C to +85°C)

CE = V

CC

-0.3 to V

CC

+1

OE  = V

CC

All inputs equal V

CC

 or V

SS

Note 1: AC power supply current above 5 MHz; 1 mA/MHz.

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 2004 Microchip Technology Inc.

DS11126H-page  3

28C04A

TABLE 1-3:

READ OPERATION AC CHARACTERISTICS

FIGURE 1-1:

READ WAVEFORMS

AC Testing Waveform:

V

IH

 = 2.4V; V

IL

 = 0.45V; V

OH

 = 2.0V; V

OL

 = 0.8V

Output Load:

1 TTL Load + 100 pF

Input Rise and Fall Times: 20 ns
Ambient Temperature:

Commercial (C): Tamb =

0°C to +70°C

Industrial 

(I):

Tamb =

-40°C to +85°C

Parameter

Sym

28C04A-15

28C04A-20

28C04A-25

Units

Conditions

Min

Max

Min

Max

Min

Max

Address to Output Delay

t

ACC

150

200

250

ns

OE = CE = V

IL

CE to Output Delay

t

CE

150

200

250

ns

OE = V

IL

OE to Output Delay

t

OE

70

80

100

ns

CE = V

IL

CE to OE High Output Float

t

OFF

0

50

0

55

0

70

ns

Output Hold from Address, CE 
or OE, whichever occurs first

t

OH

0

0

0

ns

Endurance

1M

1M

1M

cycles 25°C, Vcc = 

5.0V, Block 
Mode (Note)

Note: 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 BBS or website.

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28C04A

DS11126H-page  4

 2004 Microchip Technology Inc.

TABLE 1-4:

BYTE WRITE AC CHARACTERISTICS

FIGURE 1-2:

PROGRAMMING WAVEFORMS

AC Testing Waveform:

V

IH

 = 2.4V; V

IL

 = 0.45V; V

OH

 = 2.0V; V

OL

 = 0.8V

Output Load:

1 TTL Load + 100 pF

Input Rise/Fall Times:

20 nsec

Ambient Temperature:

Commercial  (C): Tamb= 0°C to 70°C
Industrial 

(I):

Tamb= -40°C to 85°C

Parameter

Symbol

Min

Max

Units

Remarks

Address Set-Up Time

t

AS

10

ns

Address Hold Time

t

AH

50

ns

Data Set-Up Time

t

DS

50

ns

Data Hold Time

t

DH

10

ns

Write Pulse Width

t

WPL

100

ns

Note 1

Write Pulse High Time

t

WPH

50

ns

OE Hold Time

t

OEH

10

ns

OE Set-Up Time

t

OES

10

ns

Data Valid Time

t

DV

1000

ns

Note 2

Write Cycle Time (28C04A)

t

WC

1

ms

0.5 ms typical

Write Cycle Time (28C04AF)

t

WC

200

µ

s

100 

µ

s typical

Note 1: A write cycle can be initiated be CE or WE going low, whichever occurs last.  The data is latched on the pos-

itive edge of CE or WE, whichever occurs first.

2: Data must be valid within 1000ns max. after a write cycle is initiated and must be stable at least until t

DH

 

after the positive edge of WE or CE, whichever occurs first.

t

AS

t

AH

t

WPL

t

DS

t

DH

t

OES

t

OEH

t

DV

Address

CE, WE

Data In

OE

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

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 2004 Microchip Technology Inc.

DS11126H-page  5

28C04A

FIGURE 1-3:

DATA POLLING WAVEFORMS

FIGURE 1-4:

CHIP CLEAR WAVEFORMS

Address Valid

Last Written

Address Valid

t

ACC

t

CE

t

WPL

t

WPH

t

DV

t

WC

t

OE

True Data Out

Data In

Valid

V

IH

V

IL

Data

OE

WE

CE

Address

I/O7 Out

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

IH

V

IL

V

H

V

IH

CE

OE

WE

t

S

t

H

t

W

t

S

=     = 1

µ

s

t

H

= 10ms

t

W

V

IH

V

IL

V

IH

V

IL

= 12.0V 

±

0.5V

V

H

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28C04A

DS11126H-page  6

 2004 Microchip Technology Inc.

2.0

DEVICE OPERATION

The Microchip Technology Inc. 28C04A has four basic
modes of operation—read, standby, write inhibit, and
byte write—as outlined in the following table.

2.1

Read Mode

The 28C04A has two control functions, both of which
must be logically satisfied in order to obtain data at the
outputs. Chip enable (CE) is the power control and
should be used for device selection. Output Enable
(OE) is the output control and is used to gate data to the
output pins independent of device selection. Assuming
that addresses are stable, address access time (t

ACC

)

is equal to the delay from CE  to  output  (t

CE

). Data is

available at the output tOE after the falling edge of OE,
assuming that CE has been low and addresses have
been stable for at least t

ACC

-t

OE

.

2.2

Standby Mode

The 28C04A is placed in the standby mode by applying
a high signal to the CE input. When in the standby
mode, the outputs are in a high impedance state, inde-
pendent of the OE input.

2.3

Data Protection

In order to ensure data integrity, especially during criti-
cal power-up and power-down transitions, the following
enhanced data protection circuits are incorporated:

First, an internal V

CC

 detect (3.3 volts typical) will inhibit

the initiation of non-volatile programming operation
when V

CC

 is less than the V

CC

 detect circuit trip. 

Second, there  is a WE filtering circuit that prevents WE
pulses of less than 10 ns  duration from initiating a write
cycle.

Third, holding WE or CE high or OE low, inhibits a write
cycle during power-on and power-off (V

CC

).

Operation 

Mode

CE

IE

WE

I/O

Read

L

L

H

D

OUT

Standby

H

X

X

High Z

Write Inhibit

H

X

X

High Z

Write Inhibit

X

L

X

High Z

Write Inhibit

X

X

H

High Z

Byte Write

L

H

L

D

IN

Byte Clear

Automatic Before Each “Write”

X = Any TTL level.

2.4

Write Mode

The 28C04A has a write cycle similar to that of a Static
RAM. The write cycle is completely self-timed and initi-
ated by a low going pulse on the WE pin. On the falling
edge of WE, the address information is latched. On ris-
ing edge, the data and the control pins (CE and OE) are
latched. 

2.5

Data Polling

The 28C04A features Data polling to signal the comple-
tion of a byte write cycle. During a write cycle, an
attempted read of the last byte written results in the
data complement of I/O7 (I/O0 to I/O6 are indetermin-
able). After completion of the write cycle, true data is
available. Data polling allows a simple read/compare
operation to determine the status of the chip eliminating
the need for external hardware.

2.6

Chip Clear

All data may be cleared to 1's in a chip clear cycle by
raising OE to 12 volts and bringing the WE and CE low.
This procedure clears all data.

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28C04A

28C04A 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.

Package:

L = Plastic Leaded Chip Carrier (PLCC)

P = Plastic DIP (600mill)

Temperature

Blank = 0

°

C to +70

°

Range:

I

= -40

°

C to +85

°

C

Access Time:

15

150 ns

20

200 ns

25

250 ns

Shipping:

Blank

Tube

T

Tape and Reel “L” only

Option:

Blank = twc = 1ms

F = twc = 200 

µ

s

Device:

28C04A

512 x 8 CMOS EEPROM 

28C04A

F

T

15

/P

 2004 Microchip Technology Inc.

DS11126H-page  7

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28C04A

DS11126H-page  8

 2004 Microchip Technology Inc.

NOTES:

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 2004 Microchip Technology Inc.

DS11126H-page 9

Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical
components in life support systems is not authorized except
with express written approval by Microchip. No licenses are
conveyed, implicitly or otherwise, under any intellectual
property rights.

Trademarks

The Microchip name and logo, the Microchip logo, Accuron, 
dsPIC, K

EE

L

OQ

, micro

ID

, MPLAB, PIC, PICmicro, PICSTART, 

PRO MATE, PowerSmart, rfPIC, and SmartShunt are 
registered trademarks of Microchip Technology Incorporated 
in the U.S.A. and other countries.

AmpLab, FilterLab, MXDEV, MXLAB, PICMASTER, SEEVAL, 
SmartSensor and The Embedded Control Solutions Company 
are registered trademarks of Microchip Technology 
Incorporated in the U.S.A.

Analog-for-the-Digital Age, Application Maestro, dsPICDEM, 
dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, 
FanSense, FlexROM, fuzzyLAB, In-Circuit Serial 
Programming, ICSP, ICEPIC, Migratable Memory, MPASM, 
MPLIB, MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net, 
PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, 
PowerTool, rfLAB, rfPICDEM, Select Mode, Smart Serial, 
SmartTel and Total Endurance are trademarks of Microchip 
Technology Incorporated in the U.S.A. and other countries.

SQTP is a service mark of Microchip Technology Incorporated 
in the U.S.A.

All other trademarks mentioned herein are property of their 
respective companies.

© 2004, Microchip Technology Incorporated, Printed in the 
U.S.A., All Rights Reserved.

 Printed on recycled paper.

Note the following details of the code protection feature on Microchip devices:

Microchip products meet the specification contained in their particular Microchip Data Sheet.

Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the 
intended manner and under normal conditions.

There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our 
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data 
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

Microchip is willing to work with the customer who is concerned about the integrity of their code.

Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not 
mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Microchip received ISO/TS-16949:2002 quality system certification for 
its worldwide headquarters, design and wafer fabrication facilities in 
Chandler and Tempe, Arizona and Mountain View, California in 
October 2003. The Company’s quality system processes and 
procedures are for its PICmicro

®

 

8-bit MCUs, K

EE

L

OQ

®

 

code hopping 

devices, Serial EEPROMs, microperipherals, nonvolatile memory and 
analog products. In addition, Microchip’s quality system for the design 
and manufacture of development systems is ISO 9001:2000 certified.

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 2004 Microchip Technology Inc.

AMERICAS

Corporate Office

2355 West Chandler Blvd.
Chandler, AZ  85224-6199
Tel:  480-792-7200  
Fax:  480-792-7277
Technical Support: 480-792-7627
Web Address: www.microchip.com

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Tel: 770-640-0034  
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Tel: 978-692-3848 
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Tel: 630-285-0071 
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16200 Addison Road, Suite 255
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Tel: 972-818-7423  
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Tri-Atria Office Building 
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ASIA/PACIFIC

Australia

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82-2-558-5934

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Taiwan

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Taiwan

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Taiwan

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EUROPE

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Germany

Steinheilstrasse 10
D-85737 Ismaning, Germany
Tel: 49-89-627-144-0 
Fax: 49-89-627-144-44

Italy

Via Salvatore Quasimodo, 12
20025 Legnano (MI)
Milan, Italy 
Tel: 39-0331-742611  
Fax: 39-0331-466781

Netherlands

Waegenburghtplein 4
NL-5152 JR, Drunen, Netherlands
Tel: 31-416-690399 
Fax: 31-416-690340

United Kingdom

505 Eskdale Road
Winnersh Triangle
Wokingham 
Berkshire, England RG41 5TU
Tel: 44-118-921-5869
Fax: 44-118-921-5820

07/12/04

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Maker
Microchip Technology Inc.
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