MM74C912

Features:

· Direct segment drive (100 mA typ.) 3-STATE
· 6 registers addressed like RAM
· Internal oscillator and scanning circuit
· Direct base drive to digit transistor (20 mA typ.)
· Internal segment decoder
· TTL compatible inputs

Specifications

Voltage at Any Pin
Except Inputs	-0.3V to VCC + 0.3V
Voltage at Any Input	-0.3V to +15V
Operating Temperature
Range (TA)	-40 to +85
Storage Temperature
Range (TS)	-65 to +150
Power Dissipation (PD)	Refer to PD MAX vs TA Graph
Operating VCC Range	3V to 6V
Absolute Maximum (VCC)	6.5V
Lead Temperature
(Soldering, 10 seconds)	260

Description

The MM74C912 display controllers are interface elements, with memory, that drive a 6-digit, 8-segment LED display.

The display controllers receive data information through 5 data inputs A, B, C, D and DP, and digit information through 3 address inputs K1, K2 and K3.

The input data of MM74C912 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 a decoder where 4 data bits control the format of the displayed character and 1 bit controls the decimal point. The internal oscillator of MM74C912 is controlled by a control input labeled OSCILLATOR ENABLE, (OSE), which is tied LOW in normal operation. A high level at OSE prevents automatic refresh of the display.

The 7-segment plus decimal point output information directly drives an LED display through high drive (100 mA typ.) output drivers. 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 of MM74C912 allows for duty cycle brightness control and for disabling the output drivers for power conservation.

The MM74C912 segment decoder converts BCD data into 7-segment format.

All inputs of MM74C912 are TTL compatible and do not clamp to the V_CC supply.