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. Series 54 and Series 54LS circuits are characterized for operation over the full military temperature range of -55°C to 125°C; Series 74 and Series 74LS circuits are characterized for operation from 0°C to 70°C.
● Dual Versions of the Popular "90A, "LS90 and "93A, "LS93
● "390, "LS390 … Individual 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
