7490 contains two independent counters used in counter circuits. It can perform BCD
counting or Bi-Quinary counting with the connection of the clock signal and output ports
applied to the InputA (Pin 14) and InputB (Pin 1) legs.
- It is manufactured in TTL structure with 14 legs and operates with 5V. Maximum counting frequency is 42 Mhz.
7490 Function Table
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Let’s look at this example in the diagram below..
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As it can be seen in the function table, if QA output (Pin 12) and Input B (Pin 1) connected each other and clock pulse is applied to the Input A (Pin 14), 7490 performs counting in BCD format.
You can make 7-segment display counter circuits or BCD to Decimal conversion process with BCD decoder ICs