SN74ALS191AD

Counter Dividers Overview

The SN74ALS191AD is a synchronous 4-bit reversible up/down binary counter from the Texas Instruments ALS logic family. It operates on a single down/up count-control line and features look-ahead circuitry to enhance cascading speed. The device supports asynchronous presetting via a load control input and utilizes fully synchronous counting operation where all flip-flops are clocked simultaneously. It is housed in a 16-pin Small-Outline (D) package and functions within a supply voltage range of 4.5 V to 5.5 V, with an operating temperature range of 0°C to 70°C.

Counter Dividers Feature Summary

• Synchronous counting operation eliminates output counting spikes associated with asynchronous ripple-clock counters by clocking all flip-flops simultaneously.
• Features look-ahead circuitry that enhances the speed of cascaded counters through dedicated maximum/minimum count outputs.
• Supports asynchronous programmable presetting, allowing outputs to be set to specific data levels independently of the clock input.

Counter Dividers Applications

• Modulo-N frequency division circuits utilizing the asynchronous preset capability.
• High-speed digital counting systems requiring simultaneous output transitions.
• Cascaded multi-stage counter architectures using look-ahead outputs for timing optimization.

Counter Dividers Procurement Notes

Verify the exact ordering suffix against the manufacturer's current Package Option Addendum to confirm status and material specifications. Confirm RoHS compliance and lead finish details as these vary by production batch. Ensure the selected package variant matches the required thermal and mechanical constraints for the target application environment.

Counter Dividers Selection Notes

Select this component when synchronous operation is required to prevent counting glitches common in ripple counters. The ALS series offers higher speed than standard LS logic while maintaining compatible pinouts. Verify that the system clock frequency remains within the specified limits for the chosen operating temperature range to ensure reliable performance.

Counter Dividers Part Context

This part belongs to the SN74ALS191A family of synchronous 4-bit reversible binary counters. It shares functional characteristics with other devices in the 74ALS series but is distinguished by its specific package configuration and commercial temperature rating. The device provides a robust solution for applications needing precise, glitch-free binary counting operations.

Counter Dividers Replacement Considerations

SN74ALS191ADR

Counter Dividers FAQ

How does the SN74ALS191AD handle direction changes during counting?

The direction is determined by the level of the D/U input. Changes at the control inputs have no effect on the counter contents until the next clocking event occurs, ensuring stable operation.

What is the function of the MAX/MIN output?

The MAX/MIN output produces a high-level pulse when the count reaches its maximum or minimum value, enabling look-ahead functionality for high-speed cascaded operations.