SN74HC126D Equivalent & Substitute Parts

Part Overview

The SN74HC126D is a non-inverting buffer logic IC manufactured by Texas Instruments, designed for 4-element buffering with 3-state output capability. This device operates across a 2V to 6V supply range and is housed in a 14-SOIC surface mount package. The part is currently discontinued at DiGi Electronics, making equivalent and substitute parts necessary for ongoing design support and production requirements.

Key Parameters

Parameter	Value
Manufacturer Part Number	SN74HC126D
Manufacturer	Texas Instruments
Logic Type	Buffer, Non-Inverting
Number of Elements	4
Output Type	3-State
Current - Output High, Low	7.8mA, 7.8mA
Voltage - Supply	2V ~ 6V
Operating Temperature	-40°C ~ 85°C (TA)
Package / Case	14-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for the SN74HC126D is determined by strict equivalence across the following critical parameters:

Logic Type: Buffer, Non-Inverting
Number of Elements: 4
Number of Bits per Element: 1
Output Type: 3-State
Package / Case: 14-SOIC (0.154", 3.90mm Width)
Voltage - Supply: 2V ~ 6V
Current - Output High, Low: 7.8mA, 7.8mA
Mounting Type: Surface Mount

Substitute parts are categorized into three groups:

Direct Manufacturer Equivalents: Parts with identical electrical specifications and packaging from the original or alternative manufacturers, differing only in packaging format (tube vs. cut tape/reel).

Manufacturer Recommended Substitutes: Parts recommended by manufacturers as direct replacements, with identical functional specifications but potentially extended operating temperature ranges or alternative package designations.

Parametric Equivalents: Parts with identical electrical and functional characteristics but different base product numbers (74HC125 vs. 74HC126), maintaining full compatibility within the specified parameter envelope.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Logic Type	Elements	Output Type	Current (mA)	Voltage Supply	Temp Range (°C)	Package	Product Status
SN74HC126D	Texas Instruments	Buffer, Non-Inverting	4	3-State	7.8 / 7.8	2V ~ 6V	-40 ~ 85	14-SOIC	Discontinued
SN74HC126DR	Texas Instruments	Buffer, Non-Inverting	4	3-State	7.8 / 7.8	2V ~ 6V	-40 ~ 85	14-SOIC	Active
MM74HC126M	Fairchild Semiconductor	Buffer, Non-Inverting	4	3-State	7.8 / 7.8	2V ~ 6V	-40 ~ 85	14-SOIC	Active
MM74HC126MX	Fairchild Semiconductor	Buffer, Non-Inverting	4	3-State	7.8 / 7.8	2V ~ 6V	-40 ~ 85	14-SOIC	Active
74HC126D,653	Nexperia USA Inc.	Buffer, Non-Inverting	4	3-State	7.8 / 7.8	2V ~ 6V	-40 ~ 125	14-SOIC	Active
74HC126S14-13	Diodes Incorporated	Buffer, Non-Inverting	4	3-State	5.2 / 5.2	2V ~ 6V	-40 ~ 125	14-SOIC	Active
MC74HC126ADG	onsemi	Buffer, Non-Inverting	4	3-State	7.8 / 7.8	2V ~ 6V	-55 ~ 125	14-SOIC	Obsolete
MC74HC126ADR2G	onsemi	Buffer, Non-Inverting	4	3-State	7.8 / 7.8	2V ~ 6V	-55 ~ 125	14-SOIC	Active
MM74HC125M	Fairchild Semiconductor	Buffer, Non-Inverting	4	3-State	7.8 / 7.8	2V ~ 6V	-40 ~ 85	14-SOIC	Active
SN74HC125D	Texas Instruments	Buffer, Non-Inverting	4	3-State	7.8 / 7.8	2V ~ 6V	-40 ~ 85	14-SOIC	Discontinued

Engineering Selection Recommendations

Primary Selection: SN74HC126DR (Texas Instruments) is the direct equivalent with active product status and identical specifications to the original SN74HC126D. This part maintains the same manufacturer lineage and electrical characteristics.

Extended Temperature Range Option: 74HC126D,653 (Nexperia USA Inc.) and MC74HC126ADR2G (onsemi) both provide extended operating temperature ranges (-40°C to 125°C versus -40°C to 85°C), offering enhanced reliability in demanding thermal environments while maintaining full electrical equivalence.

Output Current Consideration: 74HC126S14-13 (Diodes Incorporated) features reduced output current specifications (5.2mA versus 7.8mA). This part is suitable only for applications where lower output drive capability is acceptable.

Parametric Equivalents: MM74HC126M, MM74HC126MX, MM74HC125M, and SN74HC125D are parametrically equivalent alternatives. These parts maintain identical functional and electrical specifications within the defined parameter envelope and are suitable for direct substitution in applications where the specific base product number is not a design constraint.

Compliance Status: All recommended active parts maintain ROHS3 compliance and MSL Level 1 (Unlimited) moisture sensitivity rating, ensuring compatibility with modern manufacturing and storage requirements.

Frequently Asked Questions (FAQ)

Q: Can SN74HC126DR be used as a direct replacement for SN74HC126D?

A: Yes. SN74HC126DR is the direct equivalent with identical electrical specifications, logic type, element count, output type, current ratings, supply voltage range, and 14-SOIC packaging. The only difference is packaging format (cut tape/reel versus tube). Both are ROHS3 compliant with MSL Level 1 rating.

Q: What is the difference between 74HC126 and 74HC125 variants?

A: Both are 4-element non-inverting buffers with 3-state outputs in 14-SOIC packaging. They are parametrically equivalent and functionally interchangeable within the specified electrical envelope. The base product number difference does not affect substitution eligibility.

Q: Why does 74HC126S14-13 have lower output current (5.2mA vs. 7.8mA)?

A: This is a manufacturing variation from Diodes Incorporated. The part remains functionally equivalent but with reduced output drive capability. Use this part only if your application does not require the full 7.8mA output current specification.

Q: Are extended temperature range parts (MC74HC126ADR2G, 74HC126D,653) suitable for standard applications?

A: Yes. Extended temperature range parts are fully backward compatible with standard temperature range applications. They provide additional thermal margin and are suitable for any application using the original SN74HC126D.

Q: What is the significance of the packaging designations (tube, cut tape, reel)?

A: Packaging format affects handling, storage, and automated assembly compatibility but does not impact electrical performance or functionality. Select based on your manufacturing process requirements.

Q: Are all substitute parts ROHS3 compliant?

A: All active and recommended substitute parts listed maintain ROHS3 compliance. Verify compliance documentation for any parts sourced from alternative suppliers.

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