DESCRIPTION
The LS190 is a synchronous Up / Down BCD Decade Counter and the LS191 is a synchronous Up / Down 4-Bit Binary Counter. The operating modes of the LS190 decade counter and the LS191 binary counter are identical, with the only difference being the count sequences as noted in the state diagrams. Each circuit contains four master / slave flip-flops, with internal gating and steering logic to provide individual preset, count-up and count-down operations. Each circuit has an asynchronous parallel load capability permitting the counter to be preset to any desired number. When the Parallel Load (PL) input is LOW, information present on the Parallel Data inputs (P0 – P3) is loaded into the counter and appears on the Q outputs. This operation overrides the counting functions, as indicated in the Mode Select Table. A HIGH signal on the CE input inhibits counting. When CE is LOW, internal state change are initiated synchronously by the LOW-to-HIGH transition of the clock input. The direction of counting is determined by the U/D input signal, as indicated in the Mode Select Table.
Motorola
