74AC161PC Binary Counter IC - Equivalent & Substitute Parts

Part Overview

The 74AC161PC is a 4-bit binary counter IC manufactured by onsemi, housed in a 16-DIP package. This synchronous counter with asynchronous reset operates at a maximum count rate of 167 MHz and supports supply voltages from 2 V to 6 V. The device is classified as obsolete, making equivalent and substitute parts necessary for ongoing system maintenance, repairs, and legacy product support.

Substiute Parts

74AC161PC

onsemiIn Stock: 142974AC161PC Datasheet

Current PartRFQ

CD74AC161E

Harris CorporationIn Stock: 1975CD74AC161E Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 74AC161PC is determined by the following critical parameters:

• Logic Function: Binary counter with 4-bit capacity, 1 element
• Trigger Characteristic: Positive edge triggered
• Reset Type: Asynchronous reset capability
• Timing Architecture: Synchronous operation
• Package Compatibility: 16-DIP (0.300", 7.62mm) through-hole mounting
• Base Series: 74AC logic family

The CD74AC161E qualifies as a substitute based on matching all functional and package requirements. Variations in count rate, supply voltage range, and operating temperature do not preclude substitution when the application requirements fall within the substitute's specifications.

Parameter Comparison

Engineering Selection Recommendations

Both the 74AC161PC and CD74AC161E are obsolete products within the 74AC binary counter family. Selection between these parts depends on application-specific requirements:

74AC161PC (onsemi): Use when maximum count rate of 167 MHz is required and the application operates within the 2 V to 6 V supply range and -40°C to 85°C temperature window.

CD74AC161E (Harris Corporation): Use when extended temperature range (-55°C to 125°C) is required or when the application operates at lower supply voltages (1.5 V minimum). The 90 MHz count rate is suitable for applications not requiring the higher frequency capability of the onsemi variant.

Both devices share identical functional architecture, pin configuration, and 16-DIP package footprint, ensuring direct mechanical and electrical compatibility within their respective operating specifications.

Frequently Asked Questions (FAQ)

Q: Can the CD74AC161E directly replace the 74AC161PC in all applications?

A: Direct replacement is possible when the application's count rate requirement does not exceed 90 MHz and the operating conditions fall within the CD74AC161E's supply voltage (1.5 V ~ 5.5 V) and temperature range (-55°C ~ 125°C). If the application requires the full 167 MHz count rate of the 74AC161PC, the CD74AC161E is not suitable.

Q: Are there pin-to-pin compatibility differences between these parts?

A: No. Both the 74AC161PC and CD74AC161E use identical 16-DIP package pinouts and are functionally equivalent in terms of logic operation, reset behavior, and trigger characteristics.

Q: What is the significance of the different count rates?

A: The count rate specifies the maximum frequency at which the counter can reliably operate. The 74AC161PC supports up to 167 MHz, while the CD74AC161E supports up to 90 MHz. Selection depends on whether the application requires high-frequency operation.

Q: Why are both parts listed as obsolete?

A: Both the 74AC161PC and CD74AC161E are legacy components from the 74AC logic family. Modern applications typically use newer logic families or programmable alternatives. Obsolete status indicates limited availability and no active manufacturing.

Q: Can these parts be used interchangeably in PCB designs?

A: Yes, from a mechanical and electrical standpoint. Both parts fit the same 16-DIP footprint and have identical pinouts. However, the application's frequency and environmental requirements must be verified against each part's specifications before substitution.