The ’F191 is a reversible modulo-16 binary counter featuring synchronous counting and asynchronous presetting. The preset feature allows the ’F191 to be used in programmable dividers. The Count Enable input, the Terminal Count output and Ripple Clock output make possible a variety of methods of implementing multistage counters. In the counting modes, state changes are initiated by the rising edge of the clock. The counter has a high-speed, 125 MHz typical count frequency, supports synchronous counting, asynchronous parallel load and cascading.
The 54F/74F191 is a reversible modulo‑16 binary counter that supports synchronous up/down counting, asynchronous parallel load, and ripple‑clock outputs for multistage designs. It offers high‑speed operation up to 125 MHz and can be used in programmable dividers and other timing applications.
The device is offered in several JEDEC and EIAJ packages (DIP, SOIC, flat‑pack, etc.) with commercial and military temperature ranges. Electrical specifications include a supply voltage of 4.5 V‑5.5 V, VIH = 2.0 V, VIL = 0.8 V, and typical propagation delays of 3 ns. Absolute maximum ratings and recommended operating conditions are provided for reliable use.