DM74LS163A
Description
These synchronous, presettable counters feature an internal carry look-ahead for application in high-speed counting designs. T he D M74LS161A a nd D M74LS163A ar e 4- bit binary counters. The carry output is decoded by means of a N OR ga te, thus pr eventing spi kes d uring th e n ormal counting mode of operation. Synchronous operation is provided by having all flip-flops clocked simultaneously so that the outputs cha nge coincident w ith ea ch oth er when so instructed by th e co unt-enable i nputs and i nternal gating. This mod e o f ope ration e liminates the o utput co unting spikes which ar e no rmally associated w ith asyn chronous (ripple clock) cou nters. A buffered clock input tr iggers t he four fl ip-flops o n th e r ising (positive-going) ed ge of t he clock input waveform. These counters are fully programmable; that is, the outputs may be preset to either level. As presetting is synchronous, setting up a low level at the load input disables the counter and...
