74LS90 – Decade and Binary Counters

74LS90 Information is available here.

Part Number : 74LS90, DM74LS90M, DM74LS90N

Function : Decade and Binary Counters.

Package : DIP, SOIC 14 Pin Type

Manufacturer : Fairchild Semiconductor

Image :

74LS90 datasheet pinout

Some text files in PDF file :

DM74LS90 Decade and Binary Counters


Each of these monolithic counters contains four masterslave flip-flops and additional gating to provide a divide-bytwo counter and a three-stage binary counter for which the count cycle length is divide-by-five for the DM74LS90. All of these counters have a gated zero reset and the DM74LS90 also has gated set-to-nine inputs for use in BCD nine’s complement applications.

To use their maximum count length (decade or four bit binary), the B input is connected to the QA output. The input count pulses are applied to input A and the outputs are as described in the appropriate truth table. A symmetrical divide-by-ten count can be obtained from the DM74LS90 counters by connecting the QD output to the A input and applying the input count to the B input which gives a divide-by-ten square wave at output QA.


1. Typical power dissipation 45 mW

2. Count frequency 42 MHz

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