Arithmetic Logic Functions | MC74HC393

High-Performance Silicon-Gate CMOS

The MC54/74HC393 is identical in pinout to the LS393. The device inputs are compatible with standard CMOS outputs; with pullup resistors, they are compatible with LSTTL outputs.

This device consists of two independent 4-bit binary ripple counters with parallel outputs from each counter stage. A �b8; 256 counter can be obtained by cascading the two binary counters.

Internal flip-flops are triggered by high-to-low transitions of the clock input. Reset for the counters is asynchronous and active-high. State changes of the Q outputs do not occur simultaneously because of internal ripple delays. Therefore, decoded output signals are subject to decoding spikes and should not be used as clocks or as strobes except when gated with the Clock of the HC393.