Decade and Binary Counters
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.
Let’s look at this example in the diagram below..
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.