HD74LS669

HD74LS669 Synchronous Up / Down 4-bit Binary Counter REJ03D0493–0200 Rev.2.00 Feb.18.2005 This synchronous preset table 4-bit binary counter features an internal carry look-ahead 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 inputs and internal gating. This mode of operation helps eliminate the output counting spikes that are normally associated with asynchronous (ripple-clock) counters. A buffered clock input trigger the four master-slave flip-flops on the rising (positive-going) edge of the clock waveform. This counter is fully programmable; that is, the outputs may each be preset to either level. 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 ag...