SN74LS399D Equivalent & Substitute Parts

Part Overview

The SN74LS399D is a 4 x 2:1 multiplexer logic integrated circuit manufactured by Texas Instruments in a 16-SOIC surface mount package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The SN74LS399D operates on single supply voltage and is suitable for applications requiring multiplexing of four independent 2:1 data paths.

Substiute Parts

SN74LS399D

Texas InstrumentsIn Stock: 880SN74LS399D Datasheet

Current PartRFQ

SN74LS157D

onsemiIn Stock: 5676SN74LS157D Datasheet

Parametric EquivalentRFQ

SN74LS158D

Texas InstrumentsIn Stock: 2164SN74LS158D Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the SN74LS399D is determined by strict equivalence across the following critical parameters:

• Circuit configuration: 4 x 2:1 multiplexer topology
• Package type: 16-SOIC surface mount
• Voltage supply range: 4.75V ~ 5.25V
• Output current specifications: 400µA (high), 8mA (low)
• Operating temperature range: 0°C ~ 70°C
• Series classification: 74LS logic family

The substitute parts SN74LS157D and SN74LS158D meet all electrical and mechanical parameters required for direct substitution in applications using the SN74LS399D.

Parameter Comparison

Engineering Selection Recommendations

Both SN74LS157D and SN74LS158D provide electrical and mechanical equivalence to the SN74LS399D. Selection between these substitutes should be based on compliance and product lifecycle status:

SN74LS158D is the preferred substitute when RoHS3 compliance is required. This part is manufactured by Texas Instruments and carries Last Time Buy status, indicating controlled availability for a defined period. MSL rating of 1 (Unlimited) provides maximum flexibility for storage and handling.

SN74LS157D, manufactured by onsemi, provides functional equivalence but does not meet RoHS3 compliance requirements. This part is classified as obsolete and carries non-compliant RoHS status. Selection of this substitute should be limited to applications where RoHS compliance is not mandated.

Frequently Asked Questions (FAQ)

Q: Can SN74LS157D and SN74LS158D be used interchangeably with SN74LS399D?

A: Both parts meet the electrical and mechanical specifications required for substitution. They share identical circuit configuration (4 x 2:1 multiplexer), package type (16-SOIC), voltage supply range (4.75V ~ 5.25V), output current ratings (400µA, 8mA), and operating temperature range (0°C ~ 70°C).

Q: What is the difference between the two substitute parts?

A: The primary differences are manufacturer (onsemi vs. Texas Instruments), product status (Obsolete vs. Last Time Buy), and RoHS compliance (non-compliant vs. ROHS3 Compliant). Electrical and mechanical parameters are identical.

Q: Which substitute should I select for new designs?

A: Selection depends on compliance requirements. For RoHS3-compliant applications, use SN74LS158D. For applications without RoHS requirements, either part is electrically suitable, though SN74LS158D offers better long-term availability through Last Time Buy status.

Q: Are there any package or pinout differences between these parts?

A: No. All three parts use the 16-SOIC (0.154", 3.90mm Width) surface mount package with identical pinout and mechanical dimensions.

Q: What does Last Time Buy status mean for SN74LS158D?

A: Last Time Buy indicates the manufacturer has announced a defined period during which the part remains available before discontinuation. This provides a known window for procurement planning.