DM74LS191, DM74LS190 Datasheet - National Semiconductor

DM74LS191 - Synchronous 4-Bit Up/Down Counters

These circuits are synchronous reversible up down counters The LS191 is a 4-bit binary counter and the LS190 is a BCD counter Synchronous operation is provided by having all flip-flops clocked simultaneously so that the outputs change simultaneously when so instructed by the steering logic This mode

DM74LS191 Features

* Y Counts 8-4-2-1 BCD or binary Y Single down up count control line Y Count enable control input Y Ripple clock output for cascading Y Asynchronously presettable with load control Y Parallel outputs Y Cascadable for n-bit applications Y Average propagation delay 20 ns Y Typical clock frequency 25 MHz

DM74LS190-NationalSemiconductor.pdf