MM74C911N

MM74C911N Datasheet

MM74C911 4-Digit Expandable Segment Display Controller

Part	Datasheet
MM74C911N	MM74C911N (pdf)

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MM74C911 4-Digit Expandable Segment Display Controller MM74C911 4-Digit Expandable Segment Display Controller The MM74C911 display controller is an interface element with memory that drives a 4-digit, 8-segment LED display. The MM74C911 allows individual control of any segment in the 4-digit display. The number of segments per digit can be expanded without any external components. For example, two MM74C911’s can be cascaded to drive a 16-segment alpha-numeric display. The display controllers receive data information through 8 data lines a, and digit information through 2 address inputs K1 and K2. The input data is written into the register selected by the address information when CHIP ENABLE, CE, and WRITE ENABLE, WE, are LOW and is latched when either CE or WE return HIGH. Data hold time is not required. A self-contained internal oscillator sequentially presents the stored data to high drive 100 mA typ. 3-STATE output drivers which directly drive the LED display. The drivers are active when the control pin labeled SEGMENT OUTPUT ENABLE, SOE, is LOW and go into 3-STATE when SOE is HIGH. This feature allows for duty cycle brightness control, or for disabling the output drive for power conservation. The digit outputs directly drive the base of the digit transistor when the control pin labeled DIGIT INPUT OUTPUT, DIO, is LOW. When DIO is HIGH, the digit lines turn into inputs and the internal scanning multiplexer is disabled. When any digit line is forced HIGH by an external device, usually another MM74C911, the data information for that digit is presented to the output. In this manner, 16-segment alpha-numeric displays, 24- or 32-segment displays, or an array of discrete LED's can be controlled by the simple cascading of expandable segment display controllers. All inputs except digit inputs are TTL compatible and do not clamp input voltages above VCC. s Direct segment drive 100 mA typ. 3-STATE s 4 registers addressed like RAM s Internal oscillator and scanning circuit s Direct base drive to digit transistor s Segment expandability without external components s TTL compatible inputs s Power saver µW typ. Ordering Code: Order Number Package Number Package Description MM74C991N N28B 28-Lead Plastic Dual-In-Line Package PDIP , JEDEC MS−010, Wide Connection Diagram Pin Assignments for DIP Top View 1999 Fairchild Semiconductor Corporation DS005915.prf MM74C911 Truth Tables Input Control Digit Address Operation 0 Write Digit 1 1 Latch Digit 1 0 Write Digit 2 1 Latch Digit 2 0 Write Digit 3 1 Latch Digit 3 0 Write Digit 4 1 Latch Digit 4 X Disable Writing Output Control DIO SOE Digit Lines Operation D4 D3 D2 D1 0 R Refresh Display 1 R Disable Segment Outputs 0 Digits Are Now Inputs 0 1 Display Digit 1 0 1 0 Display Digit 2 0 1 0 Display Digit 3 0 1 0 Display Digit 4 1 0 Power Saver Mode R = Refresh digit lines sequentially pulsed X = Don’t Care Functional Description The MM74C911 display controller is manufactured on standard metal gate CMOS technology. A single 5V 74 series TTL supply can be used for power and should be bypassed at the VCC pin to suppress current transients. The digit outputs directly drive the base of a grounded emitter digit transistor without the need of a Darlington configuration. If an MM74C911 is driving a digit transistor and also supplying digit information to a cascaded MM74C911, base resistors are needed in the digit transistors to provide an adequate high level to the digit inputs of the cascaded MM74C911. As seen in the Block Diagram, these display controllers contain four 8-bit registers any one may be randomly writ-

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MM74C911 4-Digit Expandable Segment Display Controller

MM74C911 4-Digit Expandable Segment Display Controller

The MM74C911 display controller is an interface element with memory that drives a 4-digit, 8-segment LED display. The MM74C911 allows individual control of any segment in the 4-digit display. The number of segments per digit can be expanded without any external components. For example, two MM74C911’s can be cascaded to drive a 16-segment alpha-numeric display.

The display controllers receive data information through 8 data lines a, and digit information through 2 address inputs K1 and K2. The input data is written into the register selected by the address information when CHIP ENABLE, CE, and WRITE ENABLE, WE, are LOW and is latched when either CE or WE return HIGH. Data hold time is not required.

A self-contained internal oscillator sequentially presents the stored data to high drive 100 mA typ. 3-STATE output drivers which directly drive the LED display. The drivers are active when the control pin labeled SEGMENT OUTPUT ENABLE, SOE, is LOW and go into 3-STATE when SOE is HIGH. This feature allows for duty cycle brightness control, or for disabling the output drive for power conservation.

The digit outputs directly drive the base of the digit transistor when the control pin labeled DIGIT INPUT OUTPUT, DIO, is LOW. When DIO is HIGH, the digit lines turn into inputs and the internal scanning multiplexer is disabled.

When any digit line is forced HIGH by an external device, usually another MM74C911, the data information for that digit is presented to the output. In this manner, 16-segment alpha-numeric displays, 24- or 32-segment displays, or an array of discrete LED's can be controlled by the simple cascading of expandable segment display controllers. All inputs except digit inputs are TTL compatible and do not clamp input voltages above VCC.
s Direct segment drive 100 mA typ. 3-STATE s 4 registers addressed like RAM s Internal oscillator and scanning circuit s Direct base drive to digit transistor s Segment expandability without external components s TTL compatible inputs s Power saver µW typ.
Ordering Code:

Order Number Package Number

Package Description

MM74C991N

N28B
28-Lead Plastic Dual-In-Line Package PDIP , JEDEC MS−010, Wide

Connection Diagram

Pin Assignments for DIP

Top View 1999 Fairchild Semiconductor Corporation DS005915.prf

MM74C911

Truth Tables

Input Control

Digit

Address

Operation
0 Write Digit 1
1 Latch Digit 1
0 Write Digit 2
1 Latch Digit 2
0 Write Digit 3
1 Latch Digit 3
0 Write Digit 4
1 Latch Digit 4

X Disable Writing

Output Control

DIO SOE Digit Lines

Operation

D4 D3 D2 D1
0 R Refresh Display
1 R Disable Segment Outputs
0 Digits Are Now Inputs
0 1 Display Digit 1
0 1 0 Display Digit 2
0 1 0 Display Digit 3
0 1 0 Display Digit 4
1 0 Power Saver Mode

R = Refresh digit lines sequentially pulsed X = Don’t Care

Functional Description

The MM74C911 display controller is manufactured on standard metal gate CMOS technology. A single 5V 74 series TTL supply can be used for power and should be bypassed at the VCC pin to suppress current transients.

The digit outputs directly drive the base of a grounded emitter digit transistor without the need of a Darlington configuration. If an MM74C911 is driving a digit transistor and also supplying digit information to a cascaded MM74C911, base resistors are needed in the digit transistors to provide an adequate high level to the digit inputs of the cascaded MM74C911.

As seen in the Block Diagram, these display controllers contain four 8-bit registers any one may be randomly writ-

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Datasheet ID: MM74C911N 634364