SN74HCT138D Equivalent & Substitute Parts

Part Overview

The SN74HCT138D is a 1 x 3:8 Decoder/Demultiplexer logic integrated circuit manufactured by Texas Instruments in a 16-SOIC surface mount package. This part is discontinued at DiGi Electronics but remains available through alternative sources with 5650 pieces in current inventory. The device operates on a single 4.5V to 5.5V supply and is designed for applications requiring address decoding and demultiplexing functions in digital logic circuits. Due to its discontinued status, equivalent substitute parts from active manufacturers are necessary for new designs and ongoing production requirements.

Substiute Parts

SN74HCT138D

Texas InstrumentsIn Stock: 5704SN74HCT138D Datasheet

Current PartRFQ

SN74HCT138DR

Texas InstrumentsIn Stock: 7462SN74HCT138DR Datasheet

DirectRFQ

74HCT138D,653

Nexperia USA Inc.In Stock: 1040774HCT138D,653 Datasheet

MFR RecommendedRFQ

74HCT138D-Q100,118

NXP USA Inc.In Stock: 503774HCT138D-Q100,118 Datasheet

MFR RecommendedRFQ

74HCT138S16-13

Diodes IncorporatedIn Stock: 2023574HCT138S16-13 Datasheet

MFR RecommendedRFQ

74HCT377D,652

Nexperia USA Inc.In Stock: 93374HCT377D,652 Datasheet

MFR RecommendedRFQ

MC74VHCT138ADR2G

onsemiIn Stock: 65901MC74VHCT138ADR2G Datasheet

MFR RecommendedRFQ

MM74HCT138M

Fairchild SemiconductorIn Stock: 1572MM74HCT138M Datasheet

MFR RecommendedRFQ

MM74HCT138MX

Fairchild SemiconductorIn Stock: 2327MM74HCT138MX Datasheet

MFR RecommendedRFQ

SN74HCT138DG4

Texas InstrumentsIn Stock: 1077SN74HCT138DG4 Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SN74HCT138D are classified based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Critical Matching Parameters:

• Circuit configuration: 1 x 3:8 decoder/demultiplexer function
• Package type: 16-SOIC surface mount
• Voltage supply range: 4.5V ~ 5.5V
• Output current capability: 4mA minimum (high and low)
• Series compatibility: 74HCT logic family

Substitution Categories:

Direct Manufacturer Substitutes maintain identical electrical specifications and packaging from the same or equivalent manufacturers. These parts are pin-compatible and functionally equivalent with no design modifications required.

Manufacturer Recommended Substitutes are designated by original equipment manufacturers as approved alternatives. These parts meet or exceed the original specifications and are qualified for direct replacement.

Parametric Equivalents share the same functional circuit and package but may originate from different manufacturers. All critical electrical parameters remain within compatible ranges.

Enhanced Performance Alternatives provide superior specifications (higher output current, extended temperature range, or higher speed grades) while maintaining backward compatibility with the original design.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: SN74HCT138DR

The SN74HCT138DR from Texas Instruments is the direct active substitute for the discontinued SN74HCT138D. This part maintains identical electrical specifications, package configuration, and operating parameters. The primary difference is packaging format (Cut Tape & Digi-Reel versus Tube), which does not affect circuit performance. With 7420 pieces in inventory and active product status, this part provides continuity with the original design without requiring any circuit modifications.

Secondary Recommendations for Extended Temperature Range:

The 74HCT138D,653 (Nexperia), 74HCT138D-Q100,118 (NXP), and 74HCT138S16-13 (Diodes Incorporated) all provide extended operating temperature range (-40°C to 125°C versus -40°C to 85°C) while maintaining identical electrical specifications. These parts are suitable for applications requiring operation at elevated temperatures. The 74HCT138D-Q100,118 includes AEC-Q100 automotive qualification, appropriate for automotive and harsh environment applications.

Enhanced Performance Alternative: MC74VHCT138ADR2G

The MC74VHCT138ADR2G from onsemi provides doubled output current capability (8mA versus 4mA) and extended temperature range (-55°C to 125°C). This part is suitable for designs requiring higher drive capability or operation in extreme temperature environments. The 74VHCT series maintains full backward compatibility with 74HCT logic levels.

Fairchild Semiconductor Options:

The MM74HCT138M and MM74HCT138MX from Fairchild Semiconductor provide equivalent functionality with slightly enhanced output current (4.8mA). These parts are suitable for applications where marginal output current improvements are beneficial.

Compliance Considerations:

All recommended substitutes maintain ROHS3 compliance and MSL Level 1 (Unlimited) moisture sensitivity rating, consistent with the original part. Parts designated as active products ensure long-term availability and supply chain stability for production applications.

Frequently Asked Questions (FAQ)

Q: Can I use SN74HCT138DR as a direct replacement for SN74HCT138D?

A: Yes. The SN74HCT138DR is electrically and functionally identical to the SN74HCT138D. The only difference is packaging format (Cut Tape & Digi-Reel versus Tube). No circuit modifications are required.

Q: What is the difference between the 74HCT and 74VHCT series?

A: The 74VHCT series (represented by MC74VHCT138ADR2G) provides higher output current capability (8mA versus 4mA) and extended temperature range. Both series are compatible with standard TTL logic levels and can be used interchangeably in most applications. The 74VHCT variant is suitable for designs requiring higher drive capability.

Q: Are the Nexperia and NXP parts interchangeable with the Texas Instruments original?

A: Yes. The 74HCT138D,653 (Nexperia) and 74HCT138D-Q100,118 (NXP) are functionally equivalent with identical electrical specifications and package configuration. Both are active products with extended temperature range capability. The NXP variant includes AEC-Q100 automotive qualification.

Q: What does the "-Q100,118" designation mean in 74HCT138D-Q100,118?

A: The "-Q100,118" suffix indicates AEC-Q100 automotive qualification. This part meets automotive industry reliability and testing standards and is suitable for automotive applications and harsh environment use.

Q: Can I substitute MM74HCT138M or MM74HCT138MX for the original part?

A: Yes. The Fairchild Semiconductor variants (MM74HCT138M and MM74HCT138MX) are functionally equivalent with identical circuit configuration and package. Output current is slightly higher (4.8mA versus 4mA), which provides marginal performance improvement. Both parts are active products.

Q: What is the significance of the extended temperature range (-40°C to 125°C) in some substitutes?

A: Extended temperature range allows operation at higher ambient temperatures without performance degradation. If your application operates only within -40°C to 85°C, standard temperature range parts are sufficient. For applications requiring operation above 85°C, select parts with -40°C to 125°C range.

Q: Are all substitute parts ROHS3 compliant?

A: All recommended substitutes maintain ROHS3 compliance consistent with the original SN74HCT138D. Compliance status is specified in the parameter comparison table.

Q: What packaging formats are available for these substitutes?

A: Substitute parts are available in multiple packaging formats: Cut Tape & Digi-Reel (SN74HCT138DR), Tape & Reel (74HCT138D,653; 74HCT138S16-13; MC74VHCT138ADR2G), and Bulk (74HCT138D-Q100,118). Select packaging format based on your procurement and assembly requirements.