General Description
The MM74HC393 counter circuits contain independent ripple carry counters and utilize advanced silicon-gate CMOS technology. The MM74HC393 contains two 4-bit ripple carry binary counters, which can be cascaded to create a single divide-by-256 counter.
Each of the two 4-bit counters is incremented on the HIGH to-LOW transition (negative edge) of the clock input, and each has an independent clear input. When clear is set HIGH all four bits of each counter are set to a low level.
This enables count truncation and allows the implementation of divide-by-N counter configurations.
Each of the counters outputs can drive 10 low power Schottky TTL equivalent loads. This counter is functionally as well as pin equivalent to the 74LS393. All inputs are protected from damage due to static discharge by diodes to VCC and ground.

FEATUREs
■ Typical operating frequency: 50 MHz
■ Typical propagation delay: 13 ns (Ck to QA)
■ Wide operating supply voltage range: 2–6V
■ Low input current: <1 µA
■ Low quiescent supply current: 80 µA maximum (74HC Series)
■ Fanout of 10 LS-TTL loads