74LS90 Decade Counter IC

74LS90 designed as a MOD-10 decade counter that generates a BCD output code. It comes with four master-slave JK flip-flops, internally connected to provide MOD-2 (count to 2) counter and MOD-5 counter. 74LS90 also offer an independent toggle JK flip-flop by CLKA and the other three driven by the CLKB.

74LS90 Decade Counter IC operates at a Supply Voltage of 4.75 to 5.25V  with 8mA Low Level and – 0.4mA high-Level Output Current. It is a simple counter, that count from 0 to 9 cyclically in its natural mode. It counts input pulses and output received as a 4-bit binary number through pins QA, QB, QC, and QD. The binary output reset to 0000 at every tenth pulse and the count starts from 0 again.

Each of those monolithic counters contains four master-slave flip-flops. And extra gating to supply a divide-by two counter and a three-stage binary counter that the count cycle length is divide-by-five for the 74LS90. All of those counters have a gated zero reset and therefore the 74LS90 also has gated set-to-nine inputs to used in BCD nine’s complement applications. In order to utilize maximum count length (decade or four bit binary), the B input connected to the QA output. The input count pulses are applied to input A and therefore the outputs are as described within the appropriate truth table. Asymmetrical divide-by-10 count often obtained from the DM74LS90 counters by connecting the QD output to the A input. And also applying the input count to the B input which gives a divide-by-ten square wave at output QA.

APPLICATIONS:

•  Power amplifiers, Small-signal amplifiers, Operational amplifier
• Microwave amplifier, RF and IF amplifier, Voltage comparator, Multiplier.