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The NTE74LS390 is a monolithic dual 4-bit decade ripple counter in a 16-lead plastic DIP-type package that contains eight master-slave flip-flops and additional gating to implement two individual four-bit counters. This device incorporates 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 NTE74LS390 has parallel outputs from each counter stage so that any submultiple of the input count frequency is available for system-timing signals.
Individual clocks for A and B flip−flops provide dual ÷2 and ÷5 counters
Direct clear for each 4−bit counter
Dual 4−bit versions can improve system densities by reducing counter package count by 50%
Typical maximum count frequency: 35MHz
Buffered outputs reduce possibility of collector commutation
Absolute Maximum Ratings:
Supply voltage VCC: 7V
Clear input voltage: 7V
Any A or B clock input voltage: 5.5V
Operating temperature range TA: 0°C to +70°C
Storage temperature range Tstg: -65°C to +150°C
Unless otherwise specified, all voltages are referenced to GND
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