7490 IC Decade Counter DIP-14

Pin layout

74LS90 Pin Configuration

Pin No.

Pin Name

Description

1

CLKB

Clock Input 2

2

R1

Reset 1

3

R2

Reset 2

4

NC

Not Connected

5

Vcc

Positive Supply Input

6

R3

Reset 3

7

R4

Reset 4

8

Qc

Output Pin 3

9

Qb

Output Pin 2

10

Gnd

Ground

11

Qd

Output Pin 4

12

Qa

Output Pin 1

13

NC

Not Connected

14

CLKA

Clock Input 1

Features and Specifications

Typical power dissipation: 45mW

High count rates: 42MHz

Choice of counting modes

Input Clamp Diodes Limit High-Speed Termination Effect

Supply voltage: 5V

Operating Ambient Temperature Range: 55 to 125C

Brief About 7490 IC

74LS90
is basically a MOD-10 decade counter that generate a BCD output code. It consists of four master-slave JK flip-flop, which are internally connected to provide MOD-2 (count to 2) counter and MOD-5 counter. 74LS90 also have an independent toggle JK flip-flop by CLKA and other three are driven by the CLKB.

Internal Logic Diagram

How to Use Decade Counter IC?

The below circuit diagram is for
BCD decade counter
, by giving HIGH and LOW logic to the CLKA pin, IC start counts from zero to 8 at every HIGH logic. If you want to display the number on a 7-segment display you need aseven segment displaydriver IC.

74LS90 BCD Counter IC Datasheet