MM54HCT193

These high speed synchronous counters utilize advanced silicon-gate CMOS technology to achieve the high noise immunity and low power consumption of CMOS technology, along with the speeds of low power Schottky TTL. The MM54HCT193/MM74HCT193 is a binary counter having two separate clock inputs, an UP COUNT input and a DOWN COUNT input. All outputs of the flip-flops are simultaneously triggered on the low-to-high transition of either clock while the other input is held high. The direction of counting is determined by which input is clocked. This device has TTL compatible inputs. It can drive 15 LSTTL loads.

This counter may be preset by entering the desired data on the DATA A, DATA B, DATA C, and DATA D inputs. When the LOAD input is taken low, the data is loaded independently of either clock input. This feature allows the counter to be used as a divide-by-n counter by modifying the count length with the preset inputs.

In addition, the HCT193 can also be cleared. This is accomplished by inputting a high on the CLEAR input. All 4 internal stages are set to a low level independently of either COUNT input.

Both a BORROW and CARRY output are provided to enable cascading of both up and down counting functions. The BORROW output produces a negative-going pulse when the counter underflows and the CARRY outputs a pulse when the counter overflows. The counter can be cascaded by connecting the CARRY and BORROW outputs of one device to the COUNT UP and COUNT DOWN inputs, respectively, of the next device.

All inputs are protected from damage due to static discharge by diodes to VCC and ground.