MM74HC123ASJ Equivalent & Substitute Parts

Part Overview

The MM74HC123ASJ is a monostable multivibrator logic IC manufactured by onsemi, featuring dual independent circuits with Schmitt trigger inputs and 22 ns propagation delay. The device operates across a 2 V to 6 V supply range and is housed in a 16-SOP package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Substiute Parts

MM74HC123ASJ

onsemiIn Stock: 1166MM74HC123ASJ Datasheet

Current PartRFQ

74HC123D,653

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

SimilarRFQ

CD74HC123M96

Texas InstrumentsIn Stock: 50187CD74HC123M96 Datasheet

SimilarRFQ

CD74HC123ME4

Texas InstrumentsIn Stock: 969CD74HC123ME4 Datasheet

SimilarRFQ

CD74HC123MG4

Texas InstrumentsIn Stock: 920CD74HC123MG4 Datasheet

SimilarRFQ

CD74HC123MT

Texas InstrumentsIn Stock: 11170CD74HC123MT Datasheet

SimilarRFQ

CD74HC123NSR

Texas InstrumentsIn Stock: 3798CD74HC123NSR Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the MM74HC123ASJ is determined by the following critical parameters:

• Base Product Number: All substitutes must be 74HC123 series devices
• Logic Type: Monostable multivibrator with dual independent circuits
• Independent Circuits: Must be 2
• Output Current: Must match 5.2 mA for both high and low states
• Supply Voltage Range: Must support 2 V ~ 6 V operation
• Mounting Type: Surface mount only
• Package Compatibility: 16-pin SOIC variants acceptable (0.154" or 0.209" width)

Substitute parts may vary in propagation delay (22 ns to 65 ns), Schmitt trigger input availability, operating temperature range, and product status. These variations do not prevent functional substitution when the core electrical and mechanical parameters align.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: CD74HC123NSR (Texas Instruments)

This part maintains the 0.209" package width matching the original MM74HC123ASJ, ensuring direct PCB compatibility without layout modifications. The device is active in production with full RoHS3 compliance and extended operating temperature range (-55°C ~ 125°C). Propagation delay of 25 ns is within acceptable tolerance for most timing-critical applications.

Secondary Recommendation: CD74HC123M96 (Texas Instruments)

This part offers the fastest propagation delay (25 ns) among active substitutes and is available in high volume (50,100 pcs). It requires PCB footprint adjustment due to the narrower 0.154" package width but provides superior performance margin and long-term availability.

Alternative for Cost-Sensitive Applications: 74HC123D,653 (Nexperia USA Inc.)

This part is actively produced and RoHS3 compliant. The 65 ns propagation delay is acceptable for non-critical timing applications. The narrower package requires PCB modification.

Avoid: CD74HC123ME4, CD74HC123MG4, and CD74HC123MT are discontinued or discontinued at DiGi Electronics, limiting long-term procurement viability.

Frequently Asked Questions (FAQ)

Q: Can I use CD74HC123M96 as a direct replacement for MM74HC123ASJ?

A: Electrically yes, but with PCB modification. The CD74HC123M96 has identical electrical specifications (2 V ~ 6 V supply, 5.2 mA output current, dual independent circuits) but uses a narrower 0.154" package versus the original 0.209" width. Footprint adjustment is required.

Q: What is the impact of propagation delay differences?

A: The MM74HC123ASJ specifies 22 ns propagation delay. Substitutes range from 25 ns to 65 ns. For timing-critical circuits, verify that the application's timing budget accommodates the longer delay. The 25 ns variants (CD74HC123M96, CD74HC123MT, CD74HC123NSR) provide minimal performance degradation.

Q: Does the absence of Schmitt trigger input on substitute parts affect functionality?

A: The MM74HC123ASJ includes Schmitt trigger inputs; most substitutes do not. If your circuit relies on Schmitt trigger hysteresis for noise immunity, verify that the substitute's standard input thresholds are acceptable for your signal conditioning requirements.

Q: Which substitute offers the best long-term availability?

A: CD74HC123M96 (Texas Instruments) has the highest inventory (50,100 pcs) and active production status, ensuring sustained availability. CD74HC123NSR is also actively produced with 3,777 pcs in stock.

Q: Are all substitutes RoHS3 compliant?

A: All active and discontinued-at-DiGi Electronics substitutes are RoHS3 compliant. The original MM74HC123ASJ has REACH Unaffected status. All substitutes maintain REACH Unaffected status.

Q: Can I use 74HC123D,653 if my application has relaxed timing requirements?

A: Yes. The 65 ns propagation delay is acceptable for non-critical timing applications. This part is actively produced by Nexperia and offers cost advantages. Verify that your circuit's timing budget accommodates the longer delay.