74AC257PC Equivalent & Substitute Parts

Part Overview

The 74AC257PC is a 4 x 2:1 multiplexer logic integrated circuit manufactured by onsemi, housed in a 16-DIP through-hole package. This component is classified as obsolete, indicating it is no longer in active production. Due to its obsolete status and limited availability from original manufacturers, identifying functionally equivalent substitute parts is essential for system redesign, legacy system maintenance, and procurement continuity.

Substiute Parts

74AC257PC

onsemiIn Stock: 571974AC257PC Datasheet

Current PartRFQ

CD74AC257E

Harris CorporationIn Stock: 17841CD74AC257E Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 74AC257PC is determined by the following critical parameters:

• Circuit Configuration: Must be 4 x 2:1 multiplexer topology
• Package Type: Must be 16-DIP form factor with 0.300" (7.62mm) pitch for direct PCB compatibility
• Mounting Method: Must support through-hole installation
• Voltage Supply Compatibility: Operating voltage range must encompass or exceed the original specification
• Output Current Capability: Must meet or exceed the 24mA output current requirement
• Base Product Series: 74AC logic family designation

The CD74AC257E qualifies as a functional substitute based on these parameters. Both parts share the identical 4 x 2:1 multiplexer circuit, 16-DIP package footprint, and through-hole mounting configuration. The substitute part maintains backward compatibility with existing PCB designs while offering enhanced electrical performance characteristics.

Parameter Comparison

Engineering Selection Recommendations

The CD74AC257E represents a direct functional substitute for the 74AC257PC in applications requiring a 4 x 2:1 multiplexer in 16-DIP through-hole configuration. Selection between these parts should be based on the following factors:

Electrical Performance: The CD74AC257E provides superior output current capability (75mA versus 24mA), making it suitable for applications requiring higher drive capability. The expanded operating temperature range (-55°C to 125°C versus -40°C to 85°C) accommodates more demanding environmental conditions.

Supply Voltage Consideration: The overlapping voltage supply range (1.5V to 5.5V) ensures compatibility in standard logic applications. Designs operating at the lower voltage boundary (below 2V) require the CD74AC257E.

Compliance Status: Both parts are classified as obsolete and non-compliant with current RoHS directives. Procurement decisions should account for inventory availability and long-term supply chain implications.

Package Compatibility: Identical 16-DIP footprints ensure direct PCB substitution without layout modifications.

Frequently Asked Questions (FAQ)

Q: Can the CD74AC257E replace the 74AC257PC in existing designs without PCB modification?

A: Yes. Both parts use identical 16-DIP (0.300", 7.62mm) through-hole packages. Direct pin-for-pin substitution is possible without PCB redesign.

Q: What is the primary difference between these two parts?

A: The CD74AC257E offers enhanced electrical performance with 75mA output current (versus 24mA) and an extended operating temperature range (-55°C to 125°C versus -40°C to 85°C). The supply voltage range differs slightly but maintains practical overlap for standard applications.

Q: Are there voltage supply compatibility concerns?

A: The CD74AC257E operates at 1.5V to 5.5V, while the 74AC257PC operates at 2V to 6V. The common operating range is 1.5V to 5.5V. Applications requiring operation above 5.5V or below 1.5V must verify compatibility with the specific substitute part selected.

Q: Why are both parts classified as obsolete?

A: Both the 74AC257PC and CD74AC257E are legacy logic components from the 74AC series. Modern designs typically employ programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), or application-specific integrated circuits (ASICs) for multiplexing functions. These discrete multiplexer ICs remain available for legacy system support and maintenance.

Q: What packaging options are available for the CD74AC257E?

A: The CD74AC257E is supplied in tube packaging. Verify packaging requirements for your procurement and assembly processes.

Q: Is the CD74AC257E RoHS compliant?

A: No. The CD74AC257E is classified as RoHS non-compliant. Applications subject to RoHS directives require alternative solutions or exemption documentation.