74HC393D,653

The 74HC393 is a dual 4-stage binary ripple counter. Each counter features a clock input, an overriding asynchronous master reset input (nMR) and 4 buffered parallel outputs (nQ0 to nQ3). The counter advances on the HIGH-to-LOW transition of clock input. A HIGH on nMR clears the counter stages and forces the outputs LOW, independent of the state of clock input. Inputs include clamp diodes. This enables the use of current limiting resistors to interface inputs to voltages in excess of VCC.