MM5450/5451

Micrel

May 2000

1

MM5450/5451

MM5450/5451

LED Display Driver

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.

Applications

•

Industrial control indicator

•

Relay driver

•

Digital clock, thermometer, counter, voltmeter

•

Instrumentation readouts

Features

•

Continuous brightness control

•

Serial data input

•

No load signal requirement

•

Enable (on MM5450)

•

Wide power supply operation

•

TTL compatibility

•

34 or 35 outputs, 15mA capability

•

Alphanumeric capability

870 01

Figure 1.

35 OUTPUT BUFFERS

35 LATCHES

35-BIT SHIFT

REGISTERS

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 23 is Data Enable in MM5450

Pin 23 is Output 35 in MM5451

Block Diagram

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com

Ordering Information

Part Number

Junction Temp. Range

Package

MM5450BN

–40

°C to +85°C

40-pin Plastic DIP

MM5451BN

–40

°C to +85°C

40-pin Plastic DIP

MM5450BV

–40

°C to +85°C

44-pin PLCC

MM5451BV

–40

°C to +85°C

44-pin PLCC