7490 Datasheet – Decade Conunter and Divider

Part Number : 7490

Function : Package Contains a Divide-by-Two and a Divide-by-Five Counter

Manufactures : ETC

Image and Pinout

7490-datasheet-counter

 

Mode of operation

The device consists of 4 flip-flops which are connected internally to create one divide-by-2 and one divide-by-5 counters. All filp-flops have a common reset line controlled by two inputs MR1 and MR2. When both MR1 and MR2 are high the counters are cleared. Flip-flop 1 is not interally connected to the other stages, thus providing a variety of counter sequences :

a) Counting to 10 (BCD) : Output Q0 is connected to the Clock 1 input. The input pluses are applied to the Clock 0 input and the divided signal is extracted at Q3. The device counts in binary code up to 9, with the outputs returning to zero on the 10th clock pulse. Pins 2, 3 and 6, 7 must be grounded.

b) Divide by 2 and divide by 5 : Filp-flop 1 is used as a 2:1 divider and flip-flops 2, 3 and 4 are used as a 5:1 divider

Logic Diagram

7490-logic-diagram

 

7490 Datasheet