MM74HC123ASJX Equivalent & Substitute Parts

Part Overview

The MM74HC123ASJX is a monostable multivibrator logic IC manufactured by onsemi, featuring dual independent circuits with Schmitt trigger input capability and 22 ns propagation delay. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The 74HC123 series provides standardized monostable multivibrator functionality across multiple manufacturers, enabling direct substitution based on electrical and mechanical compatibility parameters.

Substiute Parts

MM74HC123ASJX

onsemiIn Stock: 1077MM74HC123ASJX Datasheet

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74HC123D,653

Nexperia USA Inc.In Stock: 198674HC123D,653 Datasheet

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CD74HC123M96

Texas InstrumentsIn Stock: 50187CD74HC123M96 Datasheet

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CD74HC123ME4

Texas InstrumentsIn Stock: 969CD74HC123ME4 Datasheet

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CD74HC123MG4

Texas InstrumentsIn Stock: 920CD74HC123MG4 Datasheet

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CD74HC123MT

Texas InstrumentsIn Stock: 11170CD74HC123MT Datasheet

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CD74HC123NSR

Texas InstrumentsIn Stock: 3798CD74HC123NSR Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the MM74HC123ASJX is determined by the following critical parameters:

• Base product number (74HC123) ensures functional equivalence
• Supply voltage range (2 V ~ 6 V) must be maintained or exceeded
• Output current capability (5.2 mA minimum for both high and low states)
• Mounting type (Surface Mount) and package compatibility
• Operating temperature range must support the application requirements
• Logic type (Monostable Multivibrator) with dual independent circuits

Substitute parts are grouped by package type and propagation delay performance. Parts with identical electrical specifications but different propagation delays (22 ns, 25 ns, 65 ns) are functionally interchangeable when timing margins permit. Package variations (16-SOIC with different widths) require PCB layout verification for mechanical fit.

Parameter Comparison

Engineering Selection Recommendations

For designs currently using the MM74HC123ASJX, the following selection criteria apply:

Package Compatibility: CD74HC123NSR maintains the original 16-SOIC (0.209", 5.30mm Width) package footprint, eliminating PCB layout modifications. All other substitutes use the narrower 16-SOIC (0.154", 3.90mm Width) package and require PCB redesign.

Product Status and Availability: CD74HC123NSR and CD74HC123M96 are active products from Texas Instruments with established supply chains. 74HC123D,653 from Nexperia USA Inc. is also active. CD74HC123ME4, CD74HC123MG4, and CD74HC123MT are discontinued or discontinued at DiGi Electronics and should be avoided for new designs.

Compliance Requirements: All substitute parts are ROHS3 compliant and REACH unaffected, meeting modern regulatory standards. The original MM74HC123ASJX does not specify RoHS status.

Temperature Range: The MM74HC123ASJX operates to 85°C. All substitutes extend to 125°C, providing enhanced thermal margin. For applications requiring the original -40°C to 85°C range, all substitutes remain compatible.

Propagation Delay: The MM74HC123ASJX specifies 22 ns. Substitutes range from 25 ns (Texas Instruments parts) to 65 ns (Nexperia part). Timing-critical applications must verify that the increased delay does not violate system requirements.

Schmitt Trigger Input: The MM74HC123ASJX includes Schmitt trigger input. No substitute parts retain this feature. Applications dependent on Schmitt trigger hysteresis require external input conditioning or alternative component selection.

Frequently Asked Questions (FAQ)

Q: Can I directly replace MM74HC123ASJX with CD74HC123NSR?

A: Yes, CD74HC123NSR is a direct replacement. Both use the 16-SOIC (0.209", 5.30mm Width) package, eliminating PCB modifications. Electrical specifications are compatible across the 2 V to 6 V supply range and -40°C to 85°C operating temperature. CD74HC123NSR is an active product from Texas Instruments.

Q: What is the impact of different propagation delays?

A: The MM74HC123ASJX specifies 22 ns propagation delay. Texas Instruments substitutes (CD74HC123M96, CD74HC123ME4, CD74HC123MG4, CD74HC123MT, CD74HC123NSR) specify 25 ns, a 3 ns increase. The Nexperia part (74HC123D,653) specifies 65 ns, a 43 ns increase. Timing-critical applications must verify that output pulse widths and circuit timing remain within specification with the substitute part's delay characteristics.

Q: Why do some substitutes have different package widths?

A: The 16-SOIC package exists in two standard widths: 0.209" (5.30mm) and 0.154" (3.90mm). The MM74HC123ASJX uses the wider 0.209" variant. Most modern substitutes use the narrower 0.154" variant. PCB footprints are not interchangeable; designs must be updated to accommodate the narrower package or select CD74HC123NSR, which maintains the original width.

Q: Is the Schmitt trigger input feature available in substitute parts?

A: No. The MM74HC123ASJX includes Schmitt trigger input capability. All listed substitute parts do not include this feature. Applications requiring Schmitt trigger hysteresis must implement external input conditioning circuits or select alternative components.

Q: Which substitute part should I select for new designs?

A: CD74HC123NSR is recommended for new designs. It is an active product from Texas Instruments, maintains the original package footprint (16-SOIC 0.209"), is ROHS3 compliant, and provides extended operating temperature range (-55°C to 125°C). CD74HC123M96 is an alternative if the narrower package (16-SOIC 0.154") is acceptable for your PCB layout.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts are ROHS3 compliant and REACH unaffected. The original MM74HC123ASJX does not specify RoHS status.

Q: Can I use 74HC123D,653 as a substitute?

A: 74HC123D,653 from Nexperia USA Inc. is functionally compatible but has significant differences. It specifies 65 ns propagation delay (versus 22 ns for the original), lacks Schmitt trigger input, uses a narrower package (16-SOIC 0.154"), and requires PCB redesign. Use only if timing margins accommodate the 43 ns delay increase.