MM74HC251M Equivalent & Substitute Parts

Part Overview

The MM74HC251M is a 1 x 8:1 multiplexer logic IC manufactured by onsemi in a 16-SOIC surface mount package. This part is classified as obsolete, which necessitates identification of equivalent and substitute components for ongoing design support and procurement. The MM74HC251M operates with a single supply voltage between 2V and 6V, making it suitable for low-voltage digital logic applications requiring multiplexing functionality.

Key Parameters

Parameter	Value
Manufacturer Part Number	MM74HC251M
Manufacturer	onsemi
Type	Multiplexer 1 x 8:1
Package / Case	16-SOIC (0.154", 3.90mm Width)
Voltage Supply	2V ~ 6V
Current - Output High, Low	5.2mA, 5.2mA
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the MM74HC251M is determined by the following critical parameters:

Circuit configuration: 1 x 8:1 multiplexer topology
Package type: 16-SOIC form factor with 0.154" width (3.90mm)
Voltage supply range: 2V ~ 6V compatibility
Output current capability: 5.2mA minimum for both high and low states
Operating temperature range: Minimum -40°C to 85°C
Mounting method: Surface mount technology

Substitute parts must maintain electrical equivalence across these parameters. Parts with identical or superior specifications within these constraints are considered direct substitutes. Parts with extended temperature ranges or higher output current ratings provide enhanced performance margins while maintaining functional compatibility.

Parameter Comparison

Part Number	Manufacturer	Circuit	Package	Voltage Supply	Output Current (High/Low)	Operating Temperature	Product Status
MM74HC251M	onsemi	1 x 8:1	16-SOIC	2V ~ 6V	5.2mA / 5.2mA	-40°C ~ 85°C	Obsolete
MC74HC251ADG	onsemi	1 x 8:1	16-SOIC	2V ~ 6V	5.2mA / 5.2mA	-55°C ~ 125°C	Active
MC74HC251ADR2G	onsemi	1 x 8:1	16-SOIC	2V ~ 6V	5.2mA / 5.2mA	-55°C ~ 125°C	Active
SN74HC251D	Texas Instruments	1 x 8:1	16-SOIC	2V ~ 6V	7.8mA / 7.8mA	-40°C ~ 85°C	Discontinued at DiGi Electronics
SN74HC251DR	Texas Instruments	1 x 8:1	16-SOIC	2V ~ 6V	7.8mA / 7.8mA	-40°C ~ 85°C	Active
SN74HC251DT	Texas Instruments	1 x 8:1	16-SOIC	2V ~ 6V	7.8mA / 7.8mA	-40°C ~ 85°C	Discontinued at DiGi Electronics
74HC251D,653	Nexperia USA Inc.	1 x 8:1	16-SOIC	2V ~ 6V	5.2mA / 5.2mA	-40°C ~ 125°C	Active
74HC251D-Q100J	Nexperia USA Inc.	1 x 8:1	16-SOIC	2V ~ 6V	5.2mA / 5.2mA	-40°C ~ 125°C	Active
CD74HC251M	Harris Corporation	1 x 8:1	16-SOIC	2V ~ 6V	5.2mA / 5.2mA	-55°C ~ 125°C	Obsolete
CD74HC251M96	Harris Corporation	1 x 8:1	16-SOIC	2V ~ 6V	5.2mA / 5.2mA	-55°C ~ 125°C	Obsolete
CD74HC251MT	Texas Instruments	1 x 8:1	16-SOIC	2V ~ 6V	5.2mA / 5.2mA	-55°C ~ 125°C	Last Time Buy

Engineering Selection Recommendations

For active production designs, MC74HC251ADG and MC74HC251ADR2G from onsemi are preferred substitutes. Both parts maintain identical electrical specifications to the MM74HC251M while offering extended operating temperature ranges (-55°C to 125°C) and active product status. MC74HC251ADR2G is supplied in Tape & Reel packaging, suitable for automated assembly processes.

SN74HC251DR from Texas Instruments is an active alternative with higher output current capability (7.8mA versus 5.2mA), providing additional drive margin. This part is available in Cut Tape and Digi-Reel packaging formats.

The Nexperia 74HC251D,653 and 74HC251D-Q100J offer active status with extended temperature range (-40°C to 125°C). The 74HC251D-Q100J includes AEC-Q100 automotive qualification, suitable for automotive-grade applications.

Parts with obsolete or last-time-buy status (CD74HC251M, CD74HC251M96, CD74HC251MT) should be avoided for new designs due to limited availability and supply discontinuation.

Frequently Asked Questions (FAQ)

Q: Can the MM74HC251M be directly replaced with MC74HC251ADG?

A: Yes. Both parts share identical circuit configuration (1 x 8:1 multiplexer), package type (16-SOIC), voltage supply range (2V ~ 6V), and output current specifications (5.2mA). The MC74HC251ADG offers extended temperature range and active product status, making it a suitable direct replacement.

Q: What is the difference between MC74HC251ADR2G and MC74HC251ADG?

A: Both parts are electrically identical. The primary difference is packaging: MC74HC251ADR2G is supplied in Tape & Reel format for automated assembly, while MC74HC251ADG is supplied in Tube packaging for manual handling.

Q: Why do some substitutes have higher output current ratings?

A: The SN74HC251D, SN74HC251DR, and SN74HC251DT from Texas Instruments specify 7.8mA output current compared to 5.2mA in the MM74HC251M. This represents enhanced drive capability while maintaining functional compatibility. Higher output current provides additional margin for driving capacitive or resistive loads.

Q: Is the 74HC251D-Q100J suitable for automotive applications?

A: Yes. The 74HC251D-Q100J carries AEC-Q100 automotive qualification and is rated for -40°C to 125°C operating temperature, meeting automotive-grade requirements.

Q: Should I use parts with obsolete status?

A: No. Parts designated as obsolete (MM74HC251M, CD74HC251M, CD74HC251M96) or last-time-buy (CD74HC251MT) have limited availability and discontinued supply. Active-status alternatives should be selected for new designs and ongoing production.

Q: Are all 16-SOIC packages mechanically compatible?

A: Yes. All listed parts use the 16-SOIC package with 0.154" width (3.90mm), ensuring mechanical compatibility in PCB layouts and sockets. Packaging format differences (Tube, Tape & Reel, Cut Tape, Bulk) affect handling and assembly methods but not physical fit.

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