LED Display Driver

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 2016 Microchip Technology Inc.

DS20005651A-page 1

MM5450/51

Features

• Continuous Brightness Control
• Serial Data Input
• No Load Signal Requirement
• Enable (MM5450 Only)
• Wide Power Supply Operation
• TTL Compatibility
• 34 or 35 Outputs, 15 mA Capability
• Alphanumeric Capability

Applications

• Industrial Control Indicator
• Relay Driver
• Digital Clock, Thermometer, Counter, Voltmeter
• Instrumentation Readouts

General Description

The MM5450 and MM5451 LED display drivers are
monolithic MOS IC’s fabricated in an N-Channel,
metal-gate process. The technology produces
low-threshold, enhancement-mode, and ion-implanted
depletion-mode devices.
A single pin controls the LED display brightness by
setting a reference current through a variable resistor
connected to the supply.

Block Diagram

35 OUTPUT BUFFERS

35 LATCHES

35-BIT SHIFT 

REGISTER

LOAD

RESET

RESET
(only available
in die form)

SERIAL DATA

22

CLOCK

21

DATA ENABLE/OUT 35

(See Note 1)

23

19

20

24

OUT 34

18

OUT 1

1

BRIGHTNESS

CONTROL

VDD

Note 1: Pin in Data Enable in MM5450

Pin in Output 25 in MM5451

LED Display Driver

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MM5450/51

DS20005651A-page 2

 2016 Microchip Technology Inc.

Connection Diagram: Die

V

OUTPUT BIT 24

MM5450/5451

DIE PINOUT

OUTPUT BIT 25
OUTPUT BIT 26
OUTPUT BIT 27
OUTPUT BIT 28
OUTPUT BIT 29

OUTPUT BIT 30
OUTPUT BIT 31
OUTPUT BIT 32

OUTPUT BIT 33

SS

V

OUTPUT

 BIT

 13

OUTPUT

 BIT

 14

OUTPUT

 BIT

 15

OUTPUT

 BIT

 16

OUTPUT

 BIT

 17

OUTPUT

 BIT

 22

OUTPUT

 BIT

 23

OUTPUT

 BIT

 18

OUTPUT

 BIT

 19

OUTPUT

 BIT

 20

OUTPUT

 BIT

 21

SS

V SS

OUTPUT BIT 12
OUTPUT BIT 11
OUTPUT BIT 10

OUTPUT BIT 9
OUTPUT BIT 8
OUTPUT BIT 7

OUTPUT BIT 6
OUTPUT BIT 5
OUTPUT BIT 4

OUTPUT BIT 3

V

OUTPUT

 BIT

 34

OUTPUT

 BIT

 35

ENABLE

D

ATA

CLK

BRIGTNESS CONTROL

RESET

OUTPUT

 BIT

 1

OUTPUT

 BIT

 2

DD

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 2016 Microchip Technology Inc.

DS20005651A-page 3

MM5450/51

Connection Diagram: Dual-Inline Package (DIP)

Connection Diagram: Plastic-Leaded Chip Carrier (PLCC)

1

40

2

39

3

38

4

37

5

36

6

35

7

34

8

33

9

32

10

31

11

30

12

29

13

28

14

27

15

26

16

25

17

24

18

23

19

22

20

21

OUTPUT BIT 18

CLOCK IN

MM5450YN

V SS

V DD

OUTPUT BIT 17

OUTPUT BIT 16

OUTPUT BIT 15

OUTPUT BIT 14

OUTPUT BIT 13

OUTPUT BIT 12

OUTPUT BIT 11

OUTPUT BIT 10

OUTPUT BIT 9

OUTPUT BIT 8

OUTPUT BIT 7

OUTPUT BIT 6

OUTPUT BIT 5

OUTPUT BIT 4

OUTPUT BIT 3

OUTPUT BIT 2

OUTPUT BIT 1

BRIGHTNESS 

CONTROL

DATA IN

DATA ENABLE

OUTPUT BIT 19

OUTPUT BIT 20

OUTPUT BIT 21

OUTPUT BIT 22

OUTPUT BIT 23

OUTPUT BIT 24

OUTPUT BIT 25

OUTPUT BIT 26

OUTPUT BIT 27

OUTPUT BIT 28

OUTPUT BIT 29

OUTPUT BIT 30

OUTPUT BIT 31

OUTPUT BIT 32

OUTPUT BIT 33

OUTPUT BIT 34

1

40

2

39

3

38

4

37

5

36

6

35

7

34

8

33

9

32

10

31

11

30

12

29

13

28

14

27

15

26

16

25

17

24

18

23

19

22

20

21

OUTPUT BIT 18

CLOCK IN

MM5451YN

V SS

V DD

OUTPUT BIT 17

OUTPUT BIT 16

OUTPUT BIT 15

OUTPUT BIT 14

OUTPUT BIT 13

OUTPUT BIT 12

OUTPUT BIT 11

OUTPUT BIT 10

OUTPUT BIT 9

OUTPUT BIT 8

OUTPUT BIT 7

OUTPUT BIT 6

OUTPUT BIT 5

OUTPUT BIT 4

OUTPUT BIT 3

OUTPUT BIT 2

OUTPUT BIT 1

BRIGHTNESS 

CONTROL

DATA IN

OUTPUT BIT 19

OUTPUT BIT 20

OUTPUT BIT 21

OUTPUT BIT 22

OUTPUT BIT 23

OUTPUT BIT 24

OUTPUT BIT 25

OUTPUT BIT 26

OUTPUT BIT 27

OUTPUT BIT 28

OUTPUT BIT 29

OUTPUT BIT 30

OUTPUT BIT 31

OUTPUT BIT 32

OUTPUT BIT 33

OUTPUT BIT 34

OUTPUT BIT 35

1

2

39

3

38

4

37

5

36

7

35

8

34

9

33

10

32

11

31

12

30

13

29

14

15

16

17

MM5450YV

V

SS

OUTPUT

 BIT

 15

OUTPUT

 BIT

 14

OUTPUT

 BIT

 16

OUTPUT

 BIT

 17

OUTPUT BIT 13

OUTPUT BIT 12

OUTPUT BIT 11

OUTPUT BIT 10

OUTPUT BIT 9

OUTPUT BIT 8

OUTPUT BIT 7

OUTPUT BIT 6

OUTPUT BIT 5

OUTPUT BIT 4

OUTPUT BIT 23

OUTPUT BIT 24

OUTPUT BIT 25

OUTPUT BIT 26

OUTPUT BIT 27

NC

OUTPUT BIT 28

OUTPUT BIT 29

OUTPUT BIT 30

OUTPUT BIT 31

OUTPUT BIT 32

NC

6

44

43

42

41

40

NC

OUTPUT

 BIT

 18

OUTPUT

 BIT

 19

OUTPUT

 BIT

 20

OUTPUT

 BIT

 21

OUTPUT

 BIT

 3

OUTPUT

 BIT

 2

OUTPUT

 BIT

 1

BRIGHTNESS CONTROL

NC

CLOCK IN

D

ATA

 I

N

DA
T

A

 ENABLE

OUTPUT

 BIT

 34

OUTPUT

 BIT

 33

23

22

21

20

19

18

24

25

26

27

28

OUTPUT

 BIT

 22

V

DD

1

2

39

3

38

4

37

5

36

7

35

8

34

9

33

10

32

11

31

12

30

13

29

14

15

16

17

MM5451YV

V

SS

OUTPUT

 BIT

 14

OUTPUT

 BIT

 15

OUTPUT

 BIT

 16

OUTPUT

 BIT

 17

OUTPUT BIT 13

OUTPUT BIT 12

OUTPUT BIT 11

OUTPUT BIT 10

OUTPUT BIT 9

OUTPUT BIT 8

OUTPUT BIT 7

OUTPUT BIT 6

OUTPUT BIT 5

OUTPUT BIT 4

OUTPUT BIT 23

OUTPUT BIT 24

OUTPUT BIT 25

OUTPUT BIT 26

OUTPUT BIT 27

NC

OUTPUT BIT 28

OUTPUT BIT 29

OUTPUT BIT 30

OUTPUT BIT 31

OUTPUT BIT 32

NC

6

44

43

42

41

40

NC

OUTPUT

 BIT

 18

OUTPUT

 BIT

 19

OUTPUT

 BIT

 20

OUTPUT

 BIT

 21

OUTPUT

 BIT

 3

OUTPUT

 BIT

 2

OUTPUT

 BIT

 1

BRIGHTNESS CONTROL

NC

CLOCK IN

D

ATA

 I

N

OUTPUT

 BIT

 35

OUTPUT

 BIT

 34

OUTPUT

 BIT

 33

23

22

21

20

19

18

24

25

26

27

28

OUTPUT

 BIT

 22

V

DD

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MM5450/51

DS20005651A-page 4

 2016 Microchip Technology Inc.

1.0

ELECTRICAL CHARACTERISTICS

Absolute Maximum Ratings †

Voltage (Any Pin)................................................................................................................................... V

SS

 to V

SS

 + 12V

Power Dissipation (+25°C) ...........................................................................................................................................1W
Power Dissipation (+85°C) ...................................................................................................................................560 mW

Operating Ratings ‡

Supply Voltage (V

DD

 – V

SS

) ..................................................................................................................... +4.75V to +11V

 Notice: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.

This is a stress rating only and functional operation of the device at those or any other conditions above those indicated
in the operational sections of this specification is not intended. Exposure to maximum rating conditions for extended
periods may affect device reliability.
‡ Notice:

 The device is not guaranteed to function outside its operating ratings.

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 2016 Microchip Technology Inc.

DS20005651A-page 5

MM5450/51

TABLE 1-1:

ELECTRICAL CHARACTERISTICS

Electrical Characteristics:

 4.5V ≤ V

DD

 ≤ 11V, V

SS

 = 0V; T

A

 = 25°C, bold values valid for –40°C ≤ T

A

 ≤ +85°C, 

unless otherwise noted.

Parameter

Symbol

Min.

Typ.

Max.

Units

Conditions

Power Supply Current

8.5

mA

–25°C to +85°C, excluding output loads

10

–40°C to +85°C, excluding output loads

Data Input Voltage

V

L

–0.3

0.8

V

Logic-0 level, ±10 µA input bias

V

H

2.2

V

DD

Logic-1 level, 4.75V ≤ V

DD

 ≤ 5.25V

V

DD

 – 

2

V

DD

V

DD

 > 5.25V

Brightness Control Input 

Current

0

0.75

mA

Note 1

Output Sink Current

10

µA

Segment off, V

OUT

 = 3.0V

0

10

Segment on, V

OUT

 = 1.8V, 

Note 2

;

Brightness input = 0 µA

2.0

2.7

4

mA

Segment on, V

OUT

 = 1.8V, 

Note 2

;

Brightness input = 100 µA

15

25

Segment on, V

OUT

 = 1.8V, 

Note 2

;

Brightness input = 750 µA

Brightness Control Input 

Voltage

3.0

4.3

V

Input current = 750 µA

Output Matching

±20

%

Note 3

Note 4

Clock Input Frequency

f

C

500

kHz

Note 5

Note 6

Clock Input High Time

t

H

950

ns

Note 5

Note 6

Clock Input Low Time

t

L

950

ns

Note 5

Note 6

Data Input Setup Time

t

DS

300

ns

Data Input Hold Setup 

Time

t

DH

300

ns

Data Enable Input Setup 

Time

t

DES

100

ns

Reset Pad Current

–8

8

µA

Die.

Note 1:

With a fixed resistor on the brightness input pin, some variation in brightness will occur among devices.

2:

See 

Figure 2-1

Figure 2-2

, and 

Figure 2-3

 for recommended operating conditions and limits. Absolute 

maximum for each output should be limited to 40 mA.

3:

Output matching is calculated as the percent variation of (I

MAX

 + I

MIN

) / 2.

4:

V

OUT

 should be regulated by user. See 

Figure 2-2

 and 

Figure 2-3

 for allowable V

OUT

 vs. I

OUT

 operation.

5:

AC input waveform specification for test purpose: t

R

 ≤ 200 ns, t

F

 ≤ 20 ns, f = 500 kHz, 50% ±10% duty 

cycle.

6:

Clock input rise and fall times must not exceed 300 ns.

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MM5450/51

DS20005651A-page 6

 2016 Microchip Technology Inc.

TEMPERATURE SPECIFICATIONS (

Note 1

)

Parameters

Sym.

Min.

Typ.

Max.

Units

Conditions

Temperature Ranges
Ambient Temperature Range

T

A

–40

+85

°C

Storage Temperature Range

T

S

–65

+150

°C

Junction Temperature

T

J

+150

°C

Lead Temperature

+300

°C

Note 1:

The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable 
junction temperature and the thermal resistance from junction to air (i.e., T

A

, T

J

JA

). Exceeding the 

maximum allowable power dissipation will cause the device operating junction temperature to exceed the 
maximum +125°C rating. Sustained junction temperatures above +125°C can impact the device reliability.

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DS20005651A-page 7

MM5450/51

2.0

TYPICAL PERFORMANCE CURVES

FIGURE 2-1:

Output Current vs. Number 

of Segments. 

FIGURE 2-2:

Output Voltage vs. LED 

Current.

FIGURE 2-3:

Power Dissipation vs. 

Temperature.

Note:

The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.

110

100

90

80

70

60

50

40

30

20

10

0

0

5

10

15

20

25

30

35

NUMBER OF SEGMENTS

OUTPUT

 CURRENT

 (mA)

V      = 1V

OUT

V      = 1.5V

OUT

V      = 2V

OUT

T   = 85°C

A

2.5

2.0

1.5

1.0

0.5

0

0

4

8

12

16

20

24

28

I      (mA)

LED

V      (V  )

OUT

O

T   = 85°C
T   = 150°C (MAX)

A
J

20 SEGM

30 SEGM

34 SEGM

1.0

0.8

0.6

0.4

0.2

0

0

20

40

60

80

TEMPERATURE (°C)

POWER DISSIP

A

TION (W)

34 SEGMENTS
V      = 1V
15 mA/SEGMENT

OUT

SAFE OPERATING

AREA

100

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MM5450/51

DS20005651A-page 8

 2016 Microchip Technology Inc.

3.0

FUNCTIONAL DESCRIPTION

The MM5450 and MM5451 are designed to drive either
4- or 5-digit alphanumeric LED displays with the added
benefit of requiring minimal interface with the display or
data source.
Data is transferred serially via two signals: clock and
serial data. Data transfer without the added
inconvenience of an external load signal is
accomplished by using a format of a leading “1”
followed by the allowed 35 data bits. These 35 data bits
are latched after the 36th has been transferred. This
scheme provides non-multiplexed, direct drive to the
LED display. Characters currently displayed (thus, data
output) changes only if the serial data bits differ from
those previously transferred.
Control of the output current for LED displays provides
for the display brightness. To prevent oscillations, a
1 nF capacitor should be connected to pin 19,
brightness control.
The 

Block Diagram

 is shown on page 1. For the

MIC5450, the /DATA ENABLE is a metal option and is
used instead of the 35th output. The output current is
typically 20-times greater than the current into pin 19,
which is set by an external variable resistor.
There is an external reset connection shown which is
available on unpackaged (die) only. 

Connection

Diagram: Die

 illustrates the die pad locations for

bonding in “chip on board” applications.

Figure 3-1

 shows the input data format. A leading “1” is

followed by 35 bits of data. After the 36th had been
transferred, a LOAD signal is generated synchronously
with the clock high state. This loads the 35 bits of data
into the latches. The low side of the clock is used to
generate a RESET signal which clears all shift registers
for the next set of data. All shift registers are static
master-slave, with no clear for the master portion of the
first register, allowing continuous operation.

FIGURE 3-1:

Input Data Format.

There must be a complete set of 36 clocks or the shift
registers will not clear.
When the chip first powers ON, an internal power ON
reset signal is generated that resets all registers and all
latches. The START bit and the first clock return the
chip to its normal operation.
The 

Connection Diagram: Dual-Inline Package (DIP)

and 

Connection Diagram: Plastic-Leaded Chip Carrier

(PLCC)

 show the pinout of the MIC5450 and MIC5451.

Bit 1 is the first bit following the start bit and it will
appear on pin 18. A logical “1” at the input will turn on
the appropriate LED.

Figure 3-2

 shows the timing relationships between

data, clock and /DATA ENABLE. A maximum clock
frequency of 0.5 MHz is assumed.

FIGURE 3-2:

Timing Diagram.

For applications where a lesser number of outputs is
used, it is possible to either increase the current per
output, or operate the part at higher than 1V V

OUT

. The

following equation can be used for calculations.

EQUATION 3-1:

Equation 3-1

 is used to plot 

Figure 2-1

Figure 2-2

, and

Figure 2-3

.

CLOCK

1

DATA

LOAD

(INTERNAL)

RESET

(INTERNAL)

START BIT 1

BIT 36

36

37

BIT 35

CLOCK

DATA

DATA ENABLE

300 nS MIN

100 nS MIN

T

J

V

OUT

I

LED

No of segments

124

o

C/W

T

A

+

=

Where:

T

J

Junction Temperature (+150°C max.)

V

OUT

Voltage at the LED driver outputs

I

LED

LED current

124°C/W Thermal resistance of the package

T

A

Ambient temperature

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 2016 Microchip Technology Inc.

DS20005651A-page 9

MM5450/51

4.0

TYPICAL APPLICATIONS

FIGURE 4-1:

Typical Application of 

Constant Current Brightness Control.

FIGURE 4-2:

Brightness Control Varying 

the Duty Cycle.

FIGURE 4-3:

Basic Electronically Tuned Radio System.

LM324

MM5450

LM317

+

¨9

240

ȍ

RAW DC

!9

¨9

1K

I19 =

2N2907

I19

PIN 19

9

20

1

5k

9

1k

CD4046

(VCO)

5V

MM74HC123

10 μS

MM5450

Q 19

20

1

LED DISPLAY

34

MM5450

DISPLAY DRIVER

ELECTRONIC

TUNING

CONTROLLER

PLL

SYNTHESIZER

KEYBOARD

STATION DETECT, ETC.

AM

FM

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MM5450/51

DS20005651A-page 10

 2016 Microchip Technology Inc.

FIGURE 4-4:

Duplexing Eight Digits with One MM5450.

9–16

2–8, 40 32–39

24–31

18 21 22 19

20

1 23 17

100k
TYP.

MM5450

V

LED

V

LED

V

LED

 = 3.0V

V

LED

 = 3.0V

CLOCK IN

DATA IN

V

DD

BRIGHTNESS

CONTROL

Maker
Microchip Technology Inc.
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