SN74F169D

The SN74F169D is a 4-bit synchronous Up/Down Binary Counter features an internal carry look-ahead circuitry for cascading in high-speed counting applications. Synchronous operation is provided by having all flip-flops clocked simultaneously so that the outputs change coincident with each other when so instructed by the count-enable (CNP\, ENT\) inputs and internal gating. This mode of operation eliminates the output counting spikes that are normally associated with asynchronous (ripple-clock) counters. A buffered clock input triggers the four flip-flops on the rising (positive-going) edge of the clock waveform. This counter is fully programmable, that is, it may be preset to any number between 0 and its maximum count. The load-input circuitry allows loading with the carry-enable output of cascaded counters. As loading is synchronous, setting up a low level at the LOAD\ input disables the counter and causes the outputs to agree with the data inputs after the next clock pulse.