SN74LS423NS Equivalent & Substitute Parts

Part Overview

The SN74LS423NS is a Monostable Multivibrator logic integrated circuit manufactured by Texas Instruments, featuring dual independent circuits with a 34 ns propagation delay. The device is packaged in a 16-SOIC surface mount configuration and operates within the standard TTL voltage supply range of 4.75 V to 5.25 V.

This part carries a Last Time Buy product status, indicating that Texas Instruments has discontinued active production. Identifying equivalent and substitute parts is necessary to ensure design continuity, maintain supply chain reliability, and support long-term product availability for applications currently utilizing this component.

Substiute Parts

SN74LS423NS

Texas InstrumentsIn Stock: 748SN74LS423NS Datasheet

Current PartRFQ

SN74LS423NSR

Texas InstrumentsIn Stock: 3249SN74LS423NSR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the SN74LS423NS is determined by strict alignment of the following critical parameters:

Functional Equivalence: Both the main part and substitute must be Monostable Multivibrator logic devices within the 74LS series, containing exactly 2 independent circuits.

Electrical Compatibility: Supply voltage range (4.75 V ~ 5.25 V), operating temperature range (0°C ~ 70°C), output current specifications (8 mA high, 400 µA low), and logic family characteristics must be identical.

Physical Compatibility: Package type must be 16-SOIC with identical physical dimensions (0.209", 5.30mm width) to ensure direct board-level substitution without layout modifications.

Compliance Requirements: RoHS3 compliance and MSL rating of 1 (Unlimited) must be maintained.

The SN74LS423NSR qualifies as a direct substitute based on these parameters. While the SN74LS423NSR exhibits improved propagation delay performance (28 ns versus 34 ns), this represents a performance enhancement rather than a deviation, as the faster specification remains within the functional requirements of applications designed for the original part.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS423NSR is the direct substitute for the SN74LS423NS based on functional, electrical, and physical parameter alignment. The primary advantage of selecting the SN74LS423NSR is its Active product status with Texas Instruments, ensuring continued availability and supply chain stability compared to the Last Time Buy status of the original part.

Both devices maintain ROHS3 compliance and identical MSL ratings, satisfying regulatory and environmental requirements. The SN74LS423NSR is available in Tape & Reel packaging format, which is standard for high-volume production environments, whereas the SN74LS423NS is supplied in tube packaging.

The improved propagation delay specification of the SN74LS423NSR (28 ns) does not introduce compatibility issues for applications designed around the 34 ns specification of the original part, as faster logic operation remains functionally transparent to circuit designs.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS423NSR be used as a direct replacement for the SN74LS423NS without circuit modifications?

A: Yes. Both devices share identical package geometry (16-SOIC), supply voltage requirements (4.75 V ~ 5.25 V), operating temperature range (0°C ~ 70°C), and output current specifications. Pin-for-pin compatibility is maintained, allowing direct board-level substitution.

Q: What is the significance of the propagation delay difference between the two parts?

A: The SN74LS423NSR exhibits a 28 ns propagation delay compared to the 34 ns specification of the SN74LS423NS. This represents improved performance. Applications designed for the original 34 ns specification will operate correctly with the faster device, as timing margins are not compromised by faster logic operation.

Q: Why is the SN74LS423NS marked as Last Time Buy?

A: Last Time Buy status indicates that Texas Instruments has discontinued active production of this part number. Existing inventory may be available through authorized distributors, but long-term availability cannot be guaranteed. The SN74LS423NSR, with Active status, provides supply continuity.

Q: Are there packaging format differences between these parts?

A: Yes. The SN74LS423NS is supplied in tube packaging, while the SN74LS423NSR is supplied in Tape & Reel (TR) format. Tape & Reel packaging is standard for automated assembly processes and high-volume production. Tube packaging is typically used for lower-volume or manual assembly applications.

Q: Do both parts meet the same compliance standards?

A: Yes. Both the SN74LS423NS and SN74LS423NSR are ROHS3 compliant with MSL rating of 1 (Unlimited), satisfying identical regulatory and environmental requirements.

Q: What is the base product number for these devices?

A: The base product number is 74LS423. Both the SN74LS423NS and SN74LS423NSR are variants of this base product, differentiated by packaging format and product status.