M74HC191

TheM54/74HC190/191 are high speedCMOS4-BIT SYNCHRONOUS UP/DOWN COUNTERS fabricated in silicon gate C²MOS technology.

They have the same high speed performance of LSTTL combined with true CMOS low power consumption.

State changes of the counter are synchronous with the LOW-to-HIGH transition of the Clock Pulse input.

An asynchronous parallel load input overrides counting and loads the data present ontheDATA inputs into the flip-flops, which makes it possible to use the circuitsasprogrammable counters. Acountenable input serves as the carry/borrow input in multi-stage counters. Control input, Down/Up, determines whether a circuit counts up or down. AMAX/MINoutputand aRippleClock output provide overflow/underflow indication and make possible a variety of methods for generating carry/borrow signals inmultistage counter applications.

All inputs are equipped with protection circuits against static discharge and transient excess voltage.