Synchronous 4-Bit Up/Down Binary Counters Positive-Edge DIP-16

These synchronous, presettable counters feature an internal carry look-ahead for application in high-speed counting designs. This mode of operation eliminates the output counting spikes 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 counters are fully programmable; that is, they can be preset to any number between 0 and 9 or 15. 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 ’HC163 devices is synchronous. A low level at the clear (CLR) input sets all four of the flip-flop outputs low after the next low-to-high transition of CLK, regardless of the levels of the enable inputs. This synchronous clear allows the count length to be modified easily by decoding the Q outputs for the maximum count desired. The active-low output of the gate used for decoding is connected to CLR to synchronously clear the counter to 0000 (LLLL). The carry look-ahead circuitry provides for cascading counters for n-bit synchronous applications without additional gating. Low Power Consumption, 80-µA Max ICC, Typical tpd = 14 ns, Synchronous Counting