7475 Technical Summary

7475 Quadruple D-Type Latch Technical Summary

Overview

The 7475 is a quadruple D-type latch integrated circuit that provides four independent transparent latches in a single package. Each latch has a data input (D), an enable input (G), and complementary outputs (Q and Q̅). The device is designed for general-purpose storage applications in digital systems, offering reliable data retention when the enable input is inactive.

This TTL-compatible component features separate enable controls for two pairs of latches, allowing flexible system design. The 7475 is characterized for operation over a wide temperature range and is suitable for various industrial and commercial applications.

Features

Four independent D-type latches in single package
Complementary outputs (Q and Q̅) for each latch
Separate enable controls (G1•2 and G3•4) for latch pairs
TTL-compatible inputs and outputs
Standardized symmetrical output characteristics
Wide operating temperature range
High noise immunity typical of TTL circuits
Low power consumption
Direct interface with CMOS, NMOS, and TTL

Applications

The 7475 is widely used in digital systems for temporary data storage and transfer applications:

Buffer storage registers
Input/output porting
Data bus interface circuits
Memory address latching
General digital logic circuits
Control system state storage
Data synchronization circuits
Bus organization systems

Electrical Characteristics

Absolute Maximum Ratings

Supply Voltage (Vcc): 7V
Input Voltage: 5.5V
Operating Temperature Range: 0°C to +70°C
Storage Temperature Range: -65°C to +150°C

Recommended Operating Conditions

Supply Voltage (Vcc): 4.75V to 5.25V
High-Level Input Voltage: 2V min
Low-Level Input Voltage: 0.8V max
Input Clamp Voltage: -1.5V
High-Level Output Current: -0.4mA
Low-Level Output Current: 16mA

DC Characteristics

High-Level Output Voltage: 2.4V min, 3.4V typ
Low-Level Output Voltage: 0.2V typ, 0.4V max
Input Clamp Current: -1.2mA max at VIN = -0.4V
High-Level Input Current: 40μA max at VIN = 2.7V
Low-Level Input Current: -1.6mA max at VIN = 0.4V
Supply Current (Total): 22mA max, 12mA typ

AC Characteristics

Propagation Delay Time (D to Q): 25ns max
Propagation Delay Time (G to Q): 25ns max
Output Transition Time: 15ns max
Maximum Clock Frequency: 35MHz typ
Setup Time (D before G↓): 20ns min
Hold Time (D after G↓): 0ns min

Functional Description

The 7475 contains four transparent D-type latches with complementary outputs. Each latch has a data input (D) and an enable input (G). When the enable input is high, the Q output follows the D input (transparent mode). When the enable input goes low, the data present at the D input at that time is stored (latched) and the Q output remains constant regardless of subsequent changes at the D input.

The enable inputs are grouped as G1•2 (controls latches 1 and 2) and G3•4 (controls latches 3 and 4), providing two independent control signals for the four latches. The truth table below describes the operation of each latch: