SN74LS138DG4 Equivalent & Substitute Parts

Part Overview

The SN74LS138DG4 is a Decoder/Demultiplexer logic IC with 1 x 3:8 circuit configuration in a 16-SOIC surface mount package, manufactured by Texas Instruments. This part is discontinued at DiGi Electronics, making substitute parts necessary for ongoing design requirements and production needs. The device operates on single supply voltage and is suitable for applications requiring address decoding and demultiplexing functions in digital logic systems.

Substiute Parts

SN74LS138DG4

Texas InstrumentsIn Stock: 1199SN74LS138DG4 Datasheet

Current PartRFQ

SN74LS138D

Texas InstrumentsIn Stock: 2343SN74LS138D Datasheet

MFR RecommendedRFQ

SN74S138AD

Texas InstrumentsIn Stock: 1055SN74S138AD Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SN74LS138DG4 are qualified based on the following critical parameters that determine functional and mechanical compatibility:

Electrical Parameters:

• Circuit configuration: 1 x 3:8 decoder/demultiplexer function
• Voltage supply range: 4.75V ~ 5.25V
• Output current specifications: 400µA (high), 8mA (low)
• Operating temperature range: 0°C ~ 70°C

Mechanical Parameters:

• Package type: 16-SOIC surface mount
• Package dimensions: 0.154" width (3.90mm)

Compliance Parameters:

• RoHS3 compliance
• Moisture Sensitivity Level: 1 (Unlimited)

Substitutes are grouped into two categories: MFR Recommended (direct replacement) and Parametric Equivalent (same electrical and mechanical specifications with different series designation).

Parameter Comparison

Engineering Selection Recommendations

SN74LS138D is the primary substitute for SN74LS138DG4. Both parts share identical electrical specifications, mechanical packaging, and compliance certifications. The SN74LS138D is currently active in production, making it the direct replacement option. The only distinction is packaging format (tube vs. original packaging) and active product status.

SN74S138AD is a parametric equivalent substitute. It maintains all critical electrical parameters, mechanical compatibility, and compliance requirements. The difference lies in the series designation (74S vs. 74LS), which represents a different logic family within the same functional class. Both parts are currently active and ROHS3 compliant.

Selection between SN74LS138D and SN74S138AD depends on design requirements and supply chain availability. Both are functionally compatible with the original SN74LS138DG4 based on the provided specifications.

Frequently Asked Questions (FAQ)

Q: Can SN74LS138D directly replace SN74LS138DG4? A: Yes. The SN74LS138D is electrically and mechanically identical to the SN74LS138DG4. Both feature the same 1 x 3:8 decoder/demultiplexer configuration, 16-SOIC package, voltage supply range (4.75V ~ 5.25V), output current specifications, and operating temperature range. The primary difference is product status (active vs. discontinued).

Q: What is the difference between SN74LS138D and SN74S138AD? A: Both parts are parametrically equivalent with identical electrical performance and mechanical packaging. The difference is the logic series: 74LS (Low-Power Schottky) versus 74S (Schottky). Both meet the specified voltage supply, output current, temperature range, and RoHS3 compliance requirements.

Q: Are all three parts in the same 16-SOIC package? A: Yes. SN74LS138DG4, SN74LS138D, and SN74S138AD all use the 16-SOIC surface mount package with 0.154" width (3.90mm). They are mechanically interchangeable on PCBs designed for this package type.

Q: What compliance certifications apply to substitute parts? A: Both SN74LS138D and SN74S138AD are ROHS3 compliant with Moisture Sensitivity Level 1 (Unlimited), matching the original SN74LS138DG4 specifications.

Q: Why is the original SN74LS138DG4 discontinued? A: The SN74LS138DG4 is discontinued at DiGi Electronics. However, functionally equivalent parts remain in active production, ensuring design continuity and supply chain availability.