Fairchild MM74C911 4-Digit Expandable Segment Display Controller Data Sheet

74C 911 4-D ig it E xp an ab le S eg en t D isp lay C tro ller

October 1987 Revised January 1999

MM74C911 4-Digit Expandable Segment Display Controller

The digit outputs directly drive the base of the digit transis-

General Description

tor when the control pin labeled DIGIT INPUT OUTPUT,

The MM74C911 display controller is an interface element

DIO, is LOW. When DIO is HIGH, the digit lines turn into

with memory that drives a 4-digit, 8-segment LED display.

inputs and the internal scanning multiplexer is disabled.

The MM74C911 allows individual control of any segment in

When any digit line is forced HIGH by an external device,

the 4-digit display. The number of segments per digit can

usually another MM74C911, the data information for that

be expanded without any external components. For exam-

digit is presented to the output. In this manner, 16-segment

ple, two MM74C911’s can be cascaded to drive a 16-seg-

alpha-numeric displays, 24- or 32-segment displays, or an

ment alpha-numeric display.

array of discrete LED's can be controlled by the simple cas-

The display controllers receive data information through 8

cading of expandable segment display controllers. All

data lines a, b…DP, and digit information through 2

inputs except digit inputs are TTL compatible and do not

address inputs K1 and K2. The input data is written into the

clamp input voltages above VCC.

register selected by the address information when CHIP ENABLE, CE, and WRITE ENABLE, WE, are LOW and is

Features

latched when either CE or WE return HIGH. Data hold time is not required. Direct segment drive (100 m A typ.) 3-STATE A self-contained internal oscillator sequentially presents 4 registers addressed like RAM the stored data to high drive (100 m A typ.) 3-STATE output

Internal oscillator and scanning circuit

drivers which directly drive the LED display. The drivers are

Direct base drive to digit transistor

active when the control pin labeled SEGMENT OUTPUT

ENABLE, SOE, is LOW and go into 3-STATE when SOE is Segment expandability without external components

HIGH. This feature allows for duty cycle brightness control, TTL compatible inputs or for disabling the output drive for power conservation.

Power saver mode—5 µW (typ.)

Ordering Code: Order Number Package Number Package Description MM74C991N N28B 28-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS−010, 0.600” Wide

Connection Diagram

Pin Assignments for DIP

Top View

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