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74LS74 Flip Flop: Pinout, Feature, Equivalent [Video]

Author: Iggy Date: 13 Jan 2021  80

74LS74 is a Dual D Flip-Flop.

The IC 74LS74 is a type of dual D-type positive edge triggered flip flop, with preset, clear, and complementary outputs. It features a large operating voltage range, wide operating conditions, and outputs directly interfaced to CMOS, NMOS, and TTL. The LOW logic level of the preset or clear inputs will set or reset outputs regardless of the logical level of the other inputs.

This blog provides you with a basic overview of the 74LS74 Flip-Flop, including its pin descriptions, functions and specifications, alternative products, etc., to help you quickly understand what 74LS74 is.

We will be glad to find that this blog can be useful for people loving electronic components :)

Still do not have idea about D-type Flip-Flop? Watch this!

 

Catalog

74LS74 Flip-Flop Pinout

74LS74 Flip-Flop Feature

74LS74 Flip-Flop Equivalents

How to use 74LS74

74LS74 Flip-Flop Applications

74LS74 Flip-Flop Package

Component Datasheet


74LS74 Flip-Flop Pinout

74LS74 Flip-Flop IC Pinout

Pin Number

Pin Symbol

Name

Description

5,9

1Q / 2Q

Output

Output Pin of the Flip Flop

6,8

1Q’(bar) / 2Q’(bar)

Complementary Output

Inverted output pin of Flip Flop

3, 11

1CLK / 2CLK

Clock Input Pin

These pins must be provided with clock pulse for the flip flop

1,13

1CLR (bar) / 2CLR (bar)

Clear Data

Resets the flip flop by clearing its memory

2,12

1D /2D

Data Input Pin

Input pin of the Flip Flop

4, 10

1PRE (bar) / 2PRE (bar)

PRE Input

Another Input pin for Flip Flop. Also referred to as a set pin

7

Vss

Ground

Connected to the ground of the system

14

Vdd/Vcc

Supply Voltage

Powers the IC typically with 5V


74LS74 Flip-Flop Feature

  • Dual D Flip Flop Package IC
  • Operating Voltage: 2V to 15V
  • Propagation Delay: 40nS
  • Minimum High-Level Input Voltage: 2 V
  • Maximum Low-Level Input Voltage: 0.8V
  • Operating Temperature: 0 to 70°C
  • High-Level Output Current: 8mA
  • Available in 14-pin SO-14, SOT42 packages

Note: You can find complete technical details in the 74LS74 data sheet at the end of this page.


74LS74 Flip-Flop Equivalents

74LVC2G80, HEF40312B


How to use 74LS74

Using a Flip-Flop is pretty straight ahead. Just use the Vcc and GND pin to power the IC. As stated earlier, each flip-flop operates independently, just connect the input signals 2 and 3 to the 1st flip-flop and you'll get the output at pins 5 and 6. The pin 3 should be provided with a clock source that normally uses a PWM signal from the MCU or 555 timers. You can use the pin to clear the data and reset the flip flop by making it high. The complete operation of the Flip Flop can be understood by taking a look at the function table below. The symbol "X" indicates that you don't care, and the up-arrow indicates the rising edge of the signal.

How to use 74LS74

INPUTS

OUTPUTS

PRE (bar)

CLR (bar)

CLK

D

Q

Q (bar)

L

H

X

X

H

L

H

L

X

X

L

H

L

L

X

X

H

H

H

H

 

H

H

L

H

H

 

L

L

H

H

H

L

X

Q0

Q(bar)

You can also simulate an IC to check that it works as you wish. Here I used logic status and logic bits to see if the IC works as it should, but you can replace them with the actual circuitry of your application to check if it fits your needs. The gif file shown below can be checked with the above truth table to make sure the IC works as desired.


74LS74 Flip-Flop Applications

  • Used as Shift Registers
  • Memory/Control Registers
  • Buffer Circuits
  • Sampling Circuits
  • Latching devices

74LS74 Flip-Flop Package

The dimensions for IC 74LS74 are given below. The dimensions are for the CDIP package. If you are using a different IC package, please refer to the 74LS74 data sheet.

74LS74 Flip-Flop Package: CDIP


That’s all for our introduction to 74LS74. If you find this blog useful, please bookmark our website Apogeeweb, we will provide you with electronic component blogs, industry news, tools, etc. that you are interested in. Stay tuned for our next blog…

Component Datasheet

74LS74 Datasheet

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