SN74HC138APWR Equivalent & Substitute Parts

Part Overview

The SN74HC138APWR is a 1 x 3:8 Decoder/Demultiplexer logic integrated circuit manufactured by Texas Instruments in the 74HC series. This component functions as a decoder that converts a 3-bit binary input into one of eight active outputs, commonly used in address decoding, data routing, and multiplexing applications. The part is currently in active product status with 3874 units in stock. Substitute parts are identified based on matching electrical specifications, circuit configuration, and mechanical packaging to ensure direct functional equivalence in circuit applications.

Key Parameters

Parameter	Value
Manufacturer Part Number	SN74HC138APWR
Manufacturer	Texas Instruments
Series	74HC
Type	Decoder/Demultiplexer
Circuit Configuration	1 x 3:8
Independent Circuits	1
Current - Output High	5.2 mA
Current - Output Low	5.2 mA
Voltage Supply Source	Single Supply
Voltage - Supply Range	2V ~ 6V
Operating Temperature Range	-40°C ~ 85°C
Mounting Type	Surface Mount
Package / Case	16-TSSOP (0.173", 4.40mm Width)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)
Product Status	Active

Substitute Part Grouping Explanation

Substitute parts for the SN74HC138APWR are qualified based on the following critical parameters that determine functional equivalence:

Electrical Equivalence Criteria:

Circuit configuration: 1 x 3:8 decoder/demultiplexer topology
Output current specifications: 5.2 mA high and low
Supply voltage range: 2V ~ 6V single supply operation
Operating temperature range: -40°C ~ 85°C

Mechanical Equivalence Criteria:

Package type: 16-TSSOP form factor
Physical dimensions: 0.173" width, 4.40mm width
Surface mount mounting type

Compliance Criteria:

RoHS3 compliance status
Moisture sensitivity level: MSL 1

All substitute parts listed maintain identical electrical performance characteristics and mechanical compatibility. Variations in packaging format (Cut Tape, Digi-Reel, Bulk, Tube) represent different distribution methods and do not affect circuit functionality.

Parameter Comparison

Part Number	Manufacturer	Circuit Config	Output Current (mA)	Supply Voltage	Temp Range (°C)	Package	Product Status	Inventory (Pcs)
SN74HC138APWR	Texas Instruments	1 x 3:8	5.2 / 5.2	2V ~ 6V	-40 ~ 85	16-TSSOP	Active	3874
SN74HC138PWR	Texas Instruments	1 x 3:8	5.2 / 5.2	2V ~ 6V	-40 ~ 85	16-TSSOP	Active	2200
SN74HC138PWT	Texas Instruments	1 x 3:8	5.2 / 5.2	2V ~ 6V	-40 ~ 85	16-TSSOP	Discontinued at DiGi Electronics	3667
MM74HC138MTCX	Fairchild Semiconductor	1 x 3:8	5.2 / 5.2	2V ~ 6V	-40 ~ 85	16-TSSOP	Active	3455
MM74HC138MTC	Fairchild Semiconductor	1 x 3:8	5.2 / 5.2	2V ~ 6V	-40 ~ 85	16-TSSOP	Active	5505
SN74HC138PW	Texas Instruments	1 x 3:8	5.2 / 5.2	2V ~ 6V	-40 ~ 85	16-TSSOP	Discontinued at DiGi Electronics	2312

Engineering Selection Recommendations

Active Product Status Parts: SN74HC138PWR (Texas Instruments) and MM74HC138MTCX or MM74HC138MTC (Fairchild Semiconductor) are recommended for new designs. These parts maintain active product status with full manufacturer support and availability. SN74HC138PWR offers the advantage of Texas Instruments manufacturing with 2200 units in stock. The Fairchild Semiconductor alternatives (MM74HC138MTCX and MM74HC138MTC) provide equivalent functionality with higher inventory levels (3455 and 5505 units respectively).

Discontinued Parts: SN74HC138PWT and SN74HC138PW are discontinued at DiGi Electronics and should be avoided for new designs. These parts may be used only in legacy system maintenance or repair applications where existing inventory is available.

Compliance Considerations: All active substitute parts maintain ROHS3 compliance and MSL 1 rating, ensuring compatibility with modern manufacturing processes and long-term storage capability without moisture sensitivity concerns.

Frequently Asked Questions (FAQ)

Q: Can SN74HC138PWR be used as a direct replacement for SN74HC138APWR? A: Yes. Both parts share identical electrical specifications (1 x 3:8 decoder configuration, 5.2 mA output current, 2V-6V supply range, -40°C to 85°C operating temperature) and mechanical packaging (16-TSSOP). The difference lies in packaging format and inventory source, not circuit functionality.

Q: What is the difference between Texas Instruments and Fairchild Semiconductor versions? A: Both manufacturers produce 74HC138 series decoders with identical electrical and mechanical specifications. The primary differences are manufacturer identity and packaging distribution methods (Cut Tape, Bulk, Tube). Circuit performance and pin compatibility are equivalent.

Q: Are the discontinued parts (SN74HC138PWT, SN74HC138PW) still usable? A: Discontinued parts retain full electrical and mechanical compatibility with active alternatives. However, they should not be specified for new designs due to unavailability from primary distributors. Use only when existing inventory is available for legacy system support.

Q: What does the packaging designation (PWR, PWT, PW, MTC, MTCX) indicate? A: These suffixes denote packaging and distribution format: PWR indicates Cut Tape with Digi-Reel packaging, PWT indicates Cut Tape format, PW indicates Tube packaging, and MTC/MTCX indicate Bulk packaging. All formats contain identical die and pin configurations.

Q: Can I mix different manufacturers in the same circuit board? A: Yes. Texas Instruments and Fairchild Semiconductor 74HC138 decoders are pin-compatible and electrically equivalent. Mixed sourcing is acceptable from a functional standpoint, though single-source procurement is preferred for supply chain consistency.

Q: What is MSL 1 and why does it matter? A: MSL (Moisture Sensitivity Level) 1 indicates unlimited shelf life without moisture sensitivity concerns. This allows extended storage without desiccant packaging or baking requirements prior to assembly.

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