DM74LS169A

54LS169 DM54LS169A DM74LS169A Synchronous 4-Bit Up Down Binary Counter June 1989 54LS169 DM54LS169A DM74LS169A Synchronous 4-Bit Up Down Binary Counter General Description This synchronous presettable 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 all change at the same time 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 edge of the clock waveform This counter is fully programmable that is the outputs may each be preset either high or low 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 The carry look-ahead circuitry permits cascading counters for n-bit synchronous applications without additional gating Both count-enable inputs (P and T) must be low to count The direction of the count is determined by the level of the up down input When the input is high the counter counts up when low it counts down Input T is fed forward to enable the carry outputs The carry output thus enabled will produce...