CD54HC160

These synchronous, presettable counters feature an internal carry look-ahead for application in high-speed counting designs. The CD54HC160 and CD54HC162 are BCD decade counters. 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 (ENP, ENT) inputs and internal gating. This mode of operation eliminates the output counting spikes that are normally associated with synchronous (ripple-clock) counters. A buffered clock (CLK) input triggers the four flip-flops on the rising (positive-going) edge of the clock waveform.

These CD54HC160 counters are fully programmable; that is, they can be preset to any number between 0 and 9. As presetting is synchronous, setting up a low level at the load input disables the counter and causes the outputs to agree with the setup data after the next clock pulse, regardless of the levels of the enable inputs. The clear function for the CD54HC160 is asynchronous. A CD54HC160 low level at the clear (CLR) input sets all four of the flip-flop outputs low, regardless of the levels of the CLK, load (LOAD), or enable inputs. The carry look-ahead circuitry provides for cascading counters for n-bit synchronous applications without additional gating. Instrumental in accomplishing this function are ENP, ENT, and a ripple-carry output (RCO). Both ENP and ENT must be high to count, and ENT is fed forward to enable RCO. Enabling RCO produces a high-level pulse while the count is maximum (9 with QA high). This high-level overflow ripple-carry pulse can be used to enable successive cascaded stages. Transitions at ENP or ENT are allowed, regardless of the level of CLK.

These CD54HC160 counters feature a fully independent clock circuit. Changes at control inputs (ENP, ENT, or LOAD) that modify the operating mode have no effect on the contents of the counter until clocking occurs. The function of the counter (whether enabled, disabled, loading, or counting) is dictated solely by the conditions meeting the stable setup and hold times. The CD54HC160 and CD54HC162 are supplied in 16-lead hermetic dual-in-line ceramic packages (F suffix), and are characterized for operation over the full military temperature range of 55°C to 125°C.