TI SN54LS393J

Each of these monolithic circuits contains eight master-slave flip-flops and additional gating to implement. two individual four-bit counters in a single package. The '390 and 'LS390 incorporate dual divide-by-two and divide-by-five counters, which can be used to implement cycle lengths equal to any whole and/or cumulative multiples of 2 and/or 5 up to divide-by-100. When connected as a bi-quinary counter, the separate divide-by-two circuit can be used to provide symmetry (a square wave) at the final output stage. The '393 and 'LS393 each comprise two independent four-bit binary counters each having a clear and a clock input. N-bit binary counters can be implemented with each package providing the capability of divide-by-256.The'390,'LS390,'393, and 'LS393 have parallel outputs from each counter stage so that any submultiple of the input count frequency is available for system-timing signals.

• Dual Versions of the Popular '90A, 'LS90 and '93A, 'LS93
• '390, 'LS390 ... lndividual Clocks for A and B Flip-Flops Provide Dual ÷2 and ÷5 Counters
• '393, 'LS393 ... Dual 4-Bit Binary Counter with Individual Clocks
• All Have Direct Clear for Each 4-Bit Counter
• Dual 4-Bit Versions Can Significantly Improve System Densities by Reducing Counter Package Count by 50%
• Typical Maximum Count Frequency ... 35 MHz
• Buffered Outputs Reduce Possibility of Collector Commutation

• Counter function for different division ratios
• Timing signal generation for digital systems