Spec

• Overview 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.　
• Features Dual Versions of the Popular '90 A,' LS90 and '93 A,' 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
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