MM74HC123AMTCX Equivalent & Substitute Parts

Part Overview

The MM74HC123AMTCX is a monostable multivibrator logic IC manufactured by onsemi, housed in a 16-TSSOP surface mount package. This device features two independent circuits with Schmitt trigger inputs and a propagation delay of 22 ns. The part is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity.

Substiute Parts

MM74HC123AMTCX

onsemiIn Stock: 3965MM74HC123AMTCX Datasheet

Current PartRFQ

74VHC123AMTCX

onsemiIn Stock: 2978874VHC123AMTCX Datasheet

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74HC123PW,112

Nexperia USA Inc.In Stock: 94074HC123PW,112 Datasheet

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74HC123PW,118

Nexperia USA Inc.In Stock: 890874HC123PW,118 Datasheet

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CD74HC123PWR

Texas InstrumentsIn Stock: 50164CD74HC123PWR Datasheet

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CD74HC123PWT

Texas InstrumentsIn Stock: 1019CD74HC123PWT Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution for the MM74HC123AMTCX is determined by the following critical parameters:

• Package compatibility: 16-TSSOP surface mount form factor
• Functional equivalence: Monostable multivibrator with two independent circuits
• Electrical compatibility: Supply voltage range, output current capability, and propagation delay performance
• Interface compatibility: Schmitt trigger input presence affects noise immunity characteristics
• Temperature rating: Operating range must meet or exceed application requirements

Substitute parts are grouped into two categories based on these criteria:

Category 1 - Direct Functional Equivalents: Parts maintaining Schmitt trigger inputs and comparable propagation delay performance within the 74HC logic family.

Category 2 - Enhanced Performance Alternatives: Parts offering improved propagation delay or extended temperature ratings while maintaining core functional requirements.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: 74VHC123AMTCX

The 74VHC123AMTCX is the preferred substitute for the MM74HC123AMTCX. Both parts maintain Schmitt trigger inputs, identical independent circuit count, and matching operating temperature range. The 74VHC variant offers superior propagation delay performance (8.1 ns versus 22 ns) and higher output current capability (8 mA versus 5.2 mA). This part is currently active in production and carries RoHS3 compliance certification.

Secondary Recommendation: CD74HC123PWR

The CD74HC123PWR from Texas Instruments provides an active production alternative with extended temperature rating (-55°C to 125°C). Propagation delay is 25 ns, closely matching the original specification. Output current and supply voltage parameters are identical to the MM74HC123AMTCX. This part is RoHS3 compliant and widely available.

Alternative Consideration: 74HC123PW,118

The 74HC123PW,118 from Nexperia is an active production part with extended temperature range (-40°C to 125°C). Note that this variant lacks Schmitt trigger inputs, which may affect noise immunity in applications with marginal signal quality. Propagation delay is 65 ns, representing a significant departure from the original specification.

Not Recommended: CD74HC123PWT

While functionally equivalent to CD74HC123PWR, this part is discontinued at DiGi Electronics and should not be selected for new designs requiring long-term supply assurance.

Frequently Asked Questions (FAQ)

Q: Can the 74VHC123AMTCX directly replace the MM74HC123AMTCX in all applications?

A: The 74VHC123AMTCX is pin-compatible and functionally equivalent with improved performance characteristics. Both parts feature Schmitt trigger inputs, identical circuit count, and matching package geometry. The primary difference is propagation delay (8.1 ns versus 22 ns) and output current capability (8 mA versus 5.2 mA), both favorable for the 74VHC variant. Verify that your application does not depend on the specific timing characteristics of the original part.

Q: What is the significance of Schmitt trigger inputs in substitution?

A: Schmitt trigger inputs provide hysteresis, improving noise immunity and signal integrity in noisy environments. The MM74HC123AMTCX and 74VHC123AMTCX both feature Schmitt triggers, while the Nexperia and some Texas Instruments variants do not. If your application relies on noise rejection, maintain Schmitt trigger functionality in your selection.

Q: Why do some substitutes have different propagation delays?

A: Propagation delay varies based on semiconductor process technology and design optimization. The 74VHC series uses advanced CMOS technology achieving 8.1 ns, while standard 74HC variants range from 22 ns to 65 ns. Verify that timing-critical applications can tolerate the substitute part's delay specification.

Q: Are all substitute parts RoHS3 compliant?

A: Yes, all listed substitute parts carry RoHS3 compliance certification. The original MM74HC123AMTCX does not specify RoHS status but is REACH unaffected.

Q: What is the difference between 74HC123PW,112 and 74HC123PW,118?

A: Both parts are functionally identical with 65 ns propagation delay and no Schmitt trigger inputs. The primary difference is packaging: 74HC123PW,112 is supplied in cut tape format, while 74HC123PW,118 is supplied in tape and reel format. The 74HC123PW,118 is currently active in production, making it the preferred choice for new designs.

Q: Can I use CD74HC123PWT for new production?

A: CD74HC123PWT is discontinued at DiGi Electronics and should not be selected for designs requiring long-term supply continuity. Use CD74HC123PWR instead, which offers identical electrical specifications and active production status.