74LS191 Synchronous Up/Down 4-bit Binary
The SN54/74LS190 is a synchronous UP/DOWN BCD Decade (8421) Counter and the SN54/74LS191 is a synchronous UP/DOWN Modulo-16 Binary Counter. State changes of the counters are synchronous with the A LOW-to-HIGH transition of the Clock Pulse input. An asynchronous Parallel Load (PL) input overrides counting and loads the data present on the P n inputs into the flip-flops, which makes it possible to use the circuits as programmable counters. A Count Enable (CE) input serves as the carry/borrow input in multi-stage counters. An Up/Down Count Control (U/D) input determines whether a circuit counts up or down. A Terminal Count (TC) output and a Ripple Clock (RC) output provide overflow/underflow indication and make possible a variety of methods for generating carry/borrow signals in multistage counter applications.
- Low Power: 90 mW Typical Dissipation
- High Speed: 25 MHz Typical Count Frequency
- Synchronous Counting
- Asynchronous Parallel Load
- Individual Preset Inputs
- Count Enable and Up/Down Control Inputs
- Input Clamp Diodes Limit High-Speed Termination Effects
NOTE: The Flatpak version has the same pinouts (Connection Diagram) as the Dual In-Line Package.