The IN74HC393 is identical in pinout to the LS/ALS393. The device inputs are compatible with standard CMOS outputs; with pullup resistors, they are compatible with LS/ALSTTL outputs.
This device consists of two independent 4-bit binary ripple counters with parallel outputs from each counter stage. A÷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 activehigh. State changes of the Q outputs do not occur simultaneously becaue 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 IN74HC393.

• Outputs Directly Interface to CMOS, NMOS, and TTL
• Operating Voltage Range: 2.0 to 6.0 V
• Low Input Current: 1.0 µA
• High Noise Immunity Characteristic of CMOS Devices