SN74ALS138ANS Equivalent & Substitute Parts

Part Overview

The SN74ALS138ANS is a decoder/demultiplexer logic integrated circuit manufactured by Texas Instruments, featuring a 1 x 3:8 circuit configuration in a 16-SOIC surface mount package. This component is classified as Last Time Buy, indicating limited availability and the necessity to identify functionally equivalent alternatives for ongoing design requirements and production planning.

Substiute Parts

SN74ALS138ANS

Texas InstrumentsIn Stock: 1487SN74ALS138ANS Datasheet

Current PartRFQ

SN74ALS138ANSR

Texas InstrumentsIn Stock: 3463SN74ALS138ANSR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SN74ALS138ANS is determined by strict equivalence across the following critical parameters:

• Decoder/Demultiplexer circuit type with 1 x 3:8 configuration
• 16-SOIC surface mount package with identical pinout and mechanical dimensions
• Single supply voltage range of 4.5V ~ 5.5V
• Output current specifications: 400µA (high), 8mA (low)
• Operating temperature range: 0°C ~ 70°C
• RoHS3 compliance and MSL Level 1 rating

The SN74ALS138ANSR qualifies as a direct substitute based on identical electrical and mechanical specifications. The primary distinction is packaging format: the original part is supplied in Tube packaging, while the substitute is supplied in Tape & Reel (TR) format. Both parts share the same base product number (74ALS138) and maintain full functional equivalence.

Parameter Comparison

Engineering Selection Recommendations

The SN74ALS138ANSR is the direct equivalent substitute for the SN74ALS138ANS. Selection between these parts should be based on procurement and assembly requirements:

The SN74ALS138ANS (Tube packaging) is suitable for low-volume applications, prototype development, and manual assembly processes. However, its Last Time Buy status indicates declining availability.

The SN74ALS138ANSR (Tape & Reel packaging) is the recommended selection for ongoing production and high-volume manufacturing. Its Active product status ensures continued availability and supply chain stability. Both parts maintain identical electrical performance, compliance certifications (ROHS3), and environmental ratings (MSL Level 1).

Frequently Asked Questions (FAQ)

Q: Can SN74ALS138ANSR be used as a direct replacement for SN74ALS138ANS?

A: Yes. Both parts are electrically and mechanically identical. The only difference is packaging format: Tube versus Tape & Reel. Pinout, performance characteristics, and compliance ratings are equivalent.

Q: What is the significance of the Last Time Buy status on the SN74ALS138ANS?

A: Last Time Buy indicates that Texas Instruments has discontinued or is discontinuing this part number. Existing inventory will be depleted without replenishment. The SN74ALS138ANSR (Active status) should be selected for new designs and ongoing production to ensure supply continuity.

Q: Are there any thermal or electrical performance differences between these parts?

A: No. Both parts operate within identical voltage ranges (4.5V ~ 5.5V), temperature ranges (0°C ~ 70°C), and output current specifications (400µA high, 8mA low).

Q: Does packaging format affect circuit board assembly compatibility?

A: Packaging format affects procurement and handling but not circuit board compatibility. Tape & Reel (TR) packaging is optimized for automated pick-and-place assembly, while Tube packaging is suitable for manual handling and lower-volume assembly. Both parts use the same 16-SOIC package footprint.

Q: Are both parts RoHS compliant?

A: Yes. Both SN74ALS138ANS and SN74ALS138ANSR are ROHS3 compliant with MSL Level 1 (Unlimited moisture sensitivity), meeting environmental and regulatory requirements for commercial and industrial applications.