DM74LS123N Equivalent & Substitute Parts

Part Overview

The DM74LS123N is a monostable multivibrator logic IC manufactured by onsemi, featuring dual independent circuits with 45 ns propagation delay in a 16-PDIP package. This component is classified as obsolete, making equivalent substitutes necessary for ongoing system support and new designs. The part operates within the standard 74LS logic family voltage range of 4.75 V to 5.25 V and is suitable for through-hole mounting applications requiring monostable timing functions.

Substiute Parts

DM74LS123N

onsemiIn Stock: 3530DM74LS123N Datasheet

Current PartRFQ

SN74LS123N

Texas InstrumentsIn Stock: 6112SN74LS123N Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the DM74LS123N is determined by strict adherence to the following electrical and mechanical parameters:

• Logic family and base product number (74LS123)
• Functional equivalence as a monostable multivibrator with dual independent circuits
• Package type and pinout compatibility (16-DIP, 0.300" spacing)
• Electrical specifications: supply voltage range (4.75 V ~ 5.25 V), output current ratings (400µA high, 8mA low), and operating temperature range (0°C ~ 70°C)
• Schmitt trigger input configuration (not present in either part)

The SN74LS123N from Texas Instruments meets all substitution criteria. While it exhibits improved propagation delay (28 ns versus 45 ns), this represents a performance enhancement rather than a deviation from compatibility requirements. Both parts share identical supply voltage, output current specifications, package configuration, and functional architecture.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS123N is the direct functional equivalent for the DM74LS123N. Selection between these parts should be based on the following criteria:

For new designs and systems requiring regulatory compliance, the SN74LS123N is preferred due to its active product status and ROHS3 compliance certification. The improved propagation delay of 28 ns provides timing margin benefits in applications where the original 45 ns specification was marginal.

For legacy system maintenance where the original 45 ns timing specification is critical to circuit operation, the DM74LS123N remains available. However, the SN74LS123N's faster propagation delay is backward-compatible and will not cause functional issues in circuits designed for the slower onsemi variant.

Both parts maintain identical electrical interfaces, supply voltage requirements, output current capabilities, and operating temperature ranges, ensuring direct pin-for-pin substitution without circuit modification.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS123N replace the DM74LS123N in existing circuits?

A: Yes. The SN74LS123N is a direct substitute with identical pinout, supply voltage range (4.75 V ~ 5.25 V), output current specifications (400µA high, 8mA low), and operating temperature range (0°C ~ 70°C). The faster propagation delay (28 ns versus 45 ns) is a performance enhancement and does not create compatibility issues.

Q: Are there package differences between these parts?

A: No. Both the DM74LS123N and SN74LS123N use the 16-DIP package with 0.300" (7.62mm) spacing, enabling direct mechanical and electrical substitution without PCB modifications.

Q: What is the significance of the propagation delay difference?

A: The SN74LS123N exhibits 28 ns propagation delay compared to the DM74LS123N's 45 ns. This represents faster circuit response time. In applications where timing margins were designed around the 45 ns specification, the faster SN74LS123N will not cause functional degradation and may improve overall system performance.

Q: Why is the DM74LS123N listed as obsolete?

A: Obsolete status indicates the part is no longer in active production by onsemi. The SN74LS123N from Texas Instruments remains in active production and is the recommended source for new inventory requirements.

Q: Are there compliance differences between these parts?

A: Yes. The SN74LS123N is ROHS3 compliant, while the DM74LS123N is RoHS non-compliant. For applications subject to RoHS regulations, the SN74LS123N is the required choice.