74ACT251PC Equivalent & Substitute Parts

Part Overview

The 74ACT251PC is a 1 x 8:1 multiplexer logic integrated circuit manufactured by onsemi in a 16-DIP through-hole package. This component is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and production continuity. The 74ACT251 series provides single-supply multiplexing functionality suitable for digital logic applications requiring channel selection from eight input lines.

Substiute Parts

74ACT251PC

onsemiIn Stock: 353674ACT251PC Datasheet

Current PartRFQ

CD74AC251M

Texas InstrumentsIn Stock: 1978CD74AC251M Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 74ACT251PC is determined by the following critical parameters:

• Functional Equivalence: Multiplexer circuit configuration must be 1 x 8:1
• Logic Family Compatibility: Base product number 74AC251 ensures functional compatibility across manufacturers
• Supply Voltage: Substitute must operate within or encompass the 4.5V ~ 5.5V range
• Output Current Capability: Substitute must meet or exceed 24mA output current specifications
• Operating Temperature: Substitute must support the -40°C ~ 85°C operating window
• Package Compatibility: Through-hole or surface-mount variants are acceptable based on application requirements

The CD74AC251M from Texas Instruments qualifies as a functional substitute based on identical multiplexer configuration (1 x 8:1), shared base product number (74AC251), and compatible electrical characteristics within the specified parameters.

Parameter Comparison

Engineering Selection Recommendations

For Direct Through-Hole Replacement: The 74ACT251PC remains the preferred choice if inventory is available, as it maintains identical package geometry and mounting technology. Current availability is 3460 pieces in new original stock.

For Surface-Mount Applications or PCB Redesign: The CD74AC251M provides functional substitution with enhanced electrical performance. The higher output current capability (75mA versus 24mA) and extended operating temperature range (-55°C ~ 125°C versus -40°C ~ 85°C) offer design margin improvements. Surface-mount packaging requires PCB layout modification. Current availability is 1917 pieces in new original stock.

Compliance Considerations: Both parts maintain REACH Unaffected status and EAR99 classification, ensuring regulatory consistency. MSL 1 rating for both components eliminates moisture sensitivity constraints during storage and handling.

Frequently Asked Questions (FAQ)

Q: Can the CD74AC251M directly replace the 74ACT251PC without circuit modification?

A: Functional substitution is valid based on identical 1 x 8:1 multiplexer configuration and compatible electrical parameters. However, package geometry differs (16-SOIC surface-mount versus 16-DIP through-hole), requiring PCB layout changes. Electrical performance of the CD74AC251M exceeds the 74ACT251PC specifications, making it electrically compatible.

Q: What is the significance of the higher output current in the CD74AC251M?

A: The CD74AC251M provides 75mA output current capability compared to 24mA in the 74ACT251PC. This increased current capacity allows driving higher-impedance loads or multiple downstream logic gates without performance degradation. Applications limited by the 24mA specification benefit from this enhancement.

Q: Are there supply voltage compatibility concerns between these parts?

A: The 74ACT251PC operates within 4.5V ~ 5.5V. The CD74AC251M operates within 1.5V ~ 5.5V, encompassing the original specification range. Both parts are compatible with standard 5V logic supply systems. The CD74AC251M provides additional flexibility for lower-voltage applications.

Q: What packaging considerations apply to substitution?

A: The 74ACT251PC uses through-hole 16-DIP packaging for breadboard and traditional PCB assembly. The CD74AC251M uses surface-mount 16-SOIC packaging, requiring SMD assembly equipment and modified PCB footprints. Package selection depends on manufacturing capability and PCB design constraints.

Q: Do both parts have identical temperature operating ranges?

A: No. The 74ACT251PC operates from -40°C ~ 85°C, while the CD74AC251M operates from -55°C ~ 125°C. Applications requiring extended temperature performance benefit from the CD74AC251M. Standard industrial applications within -40°C ~ 85°C show no functional difference.

Q: What is the product status impact on long-term availability?

A: Both parts are classified as obsolete or discontinued, indicating no new production. Substitution decisions should prioritize current inventory levels and long-term supply chain planning. The 74ACT251PC shows higher current availability (3460 pieces) compared to the CD74AC251M (1917 pieces).