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HD74HC668/HD74HC669
Synchronous UP/Down Decade Counter Synchronous Up/Down 4-bit binary Counter
Description
This synchronous presettable decade counter features an internal carry look-ahead for cascading in highspeed 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 countenable 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 triggers 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.
HD74HC668 Datasheet
