MC74AC161N

Counter Dividers Overview

The MC74AC161N is a high-speed synchronous modulo-16 binary counter manufactured by onsemi in a 16-pin PDIP package. It operates within a supply voltage range of 2 V to 6 V and supports a typical count rate of 125 MHz. The device features an asynchronous Master Reset input that forces outputs LOW, parallel data inputs for presettable loading, and two Count Enable inputs (CEP and CET). It includes a Terminal Count output for multistage expansion and provides outputs capable of sourcing or sinking 24 mA.

Counter Dividers Feature Summary

• Synchronous counting and loading with D-type edge-triggered flip-flops
• Asynchronous Master Reset input overriding all other functions
• Parallel load capability via dedicated P0-P3 inputs
• Terminal Count output for synchronous multistage expansion

Counter Dividers Applications

• Programmable frequency dividers
• Synchronous multistage counters
• Digital timing sequences
• Event counting logic

Counter Dividers Procurement Notes

Verify the specific ordering suffix 'N' corresponds to the 16-lead Plastic Dual In-Line Package (PDIP) as defined in the datasheet. Confirm RoHS compliance status for the specific production lot, as historical documentation indicates variations between standard and Pb-free devices. Ensure the application environment remains within the specified -40°C to +85°C operating temperature range.

Counter Dividers Selection Notes

Select this component when an asynchronous reset function is required for immediate output clearing. The AC series offers a wider supply voltage flexibility compared to ACT variants. Verify that the system clock rise and fall times adhere to the recommended limits for the chosen supply voltage to ensure reliable synchronous operation without race conditions.

Counter Dividers Part Context

This part belongs to the MC74AC161/ACT161 family of synchronous presettable binary counters. It is functionally distinct from the MC74AC163, which utilizes a Synchronous Reset input instead of an Asynchronous Master Reset. Both share similar counting architectures but differ in reset timing behavior relative to the clock edge.

Counter Dividers Replacement Considerations

CD74AC161E (Texas Instruments)

Counter Dividers FAQ

How does the reset mechanism of the MC74AC161N differ from the MC74AC163?

The MC74AC161N features an asynchronous Master Reset that immediately forces outputs LOW regardless of the clock state. In contrast, the MC74AC163 uses a Synchronous Reset that clears outputs only on the rising edge of the clock pulse.

What is the purpose of the Terminal Count (TC) output?

The TC output goes HIGH when the counter reaches state 15 and CET is HIGH. It is designed to cascade with the Count Enable Parallel (CEP) and Count Enable Trickle (CET) inputs to form synchronous multistage counters.