74VHCT138AMTC Equivalent & Substitute Parts

Part Overview

The 74VHCT138AMTC is a decoder/demultiplexer logic IC manufactured by onsemi, featuring a 1 x 3:8 circuit configuration in a 16-TSSOP surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

The 74VHCT138AMTC operates with a single 4.5V to 5.5V supply, delivers 8mA output current (high and low), and functions across the -40°C to 85°C temperature range. Its obsolete status requires designers to identify active alternatives that maintain electrical and mechanical compatibility.

Key Parameters

Parameter	Value
Type	Decoder/Demultiplexer
Circuit Configuration	1 x 3:8
Output Current (High/Low)	8mA / 8mA
Supply Voltage	4.5V – 5.5V
Operating Temperature	-40°C to 85°C
Package Type	16-TSSOP (0.173", 4.40mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the 74VHCT138AMTC is determined by the following critical parameters:

Circuit Configuration: All substitutes must maintain the 1 x 3:8 decoder/demultiplexer function
Package Type: Primary substitutes use 16-TSSOP; alternatives with 16-SSOP require PCB layout verification
Supply Voltage: All substitutes operate within 4.5V to 5.5V range
Output Current: Substitutes with 8mA (high/low) are direct equivalents; 12mA variants provide enhanced drive capability
Operating Temperature: Substitutes with -40°C to 85°C match the original; extended range (-55°C to 125°C) variants offer broader environmental coverage
Product Status: Active parts are preferred over obsolete or last-time-buy classifications
Compliance: RoHS3 compliance and MSL 1 rating maintained across all substitutes

Parameter Comparison

Part Number	Manufacturer	Series	Output Current (mA)	Operating Temp (°C)	Package	Product Status	Packaging Type
74VHCT138AMTC	onsemi	74VHCT	8 / 8	-40 to 85	16-TSSOP	Obsolete	Bulk
MC74VHCT138ADTRG	onsemi	74VHCT	8 / 8	-55 to 125	16-TSSOP	Active	Tape & Reel
CAHCT138QPWRG4Q1	Texas Instruments	74AHCT	8 / 8	-40 to 125	16-TSSOP	Active	Tape & Reel
SN74AHCT138PWR	Texas Instruments	74AHCT	8 / 8	-40 to 85	16-TSSOP	Active	Cut Tape & Digi-Reel
SN74LV138ATPW	Texas Instruments	74LV	12 / 12	-40 to 125	16-TSSOP	Last Time Buy	Tube
74AHCT138PW,118	NXP Semiconductors	74AHCT	8 / 8	-40 to 125	16-TSSOP	Active	Bulk
74AHCT138PW-Q100J	Nexperia USA Inc.	74AHCT	8 / 8	-40 to 125	16-TSSOP	Active	Tape & Reel
74AHCT138T16-13	Diodes Incorporated	74AHCT	8 / 8	-40 to 125	16-TSSOP	Active	Tape & Reel
SN74AHCT138MPWREP	Texas Instruments	74AHCT	8 / 8	-55 to 125	16-TSSOP	Active	Tape & Reel
74HCT138T16-13	Diodes Incorporated	74HCT	4 / 4	-40 to 125	16-TSSOP	Active	Tape & Reel
SN74AHCT138DBR	Texas Instruments	74AHCT	8 / 8	-40 to 85	16-SSOP	Active	Tape & Reel

Engineering Selection Recommendations

Direct Equivalents (Preferred for 74VHCT138AMTC Replacement)

MC74VHCT138ADTRG (onsemi) maintains the 74VHCT series lineage with active product status and extended operating temperature range (-55°C to 125°C). This part provides the closest functional match while offering improved temperature coverage.

SN74AHCT138PWR (Texas Instruments) delivers identical electrical specifications (8mA output current, -40°C to 85°C) in 16-TSSOP packaging with active status. This part matches the original temperature range precisely.

Extended Temperature Alternatives

CAHCT138QPWRG4Q1 (Texas Instruments) and 74AHCT138PW-Q100J (Nexperia USA Inc.) both extend the operating range to -40°C to 125°C while maintaining 8mA output current and 16-TSSOP packaging. The CAHCT138QPWRG4Q1 includes automotive-grade qualification (AEC-Q100), suitable for automotive applications.

SN74AHCT138MPWREP (Texas Instruments) provides -55°C to 125°C coverage with 8mA output current in 16-TSSOP packaging and active product status.

Enhanced Drive Capability

SN74LV138ATPW (Texas Instruments) offers 12mA output current (high and low) with extended temperature range (-40°C to 125°C). This part is classified as last-time-buy; use only when enhanced drive capability is required and long-term availability is not critical.

Reduced Drive Capability

74HCT138T16-13 (Diodes Incorporated) delivers 4mA output current with active status and extended temperature range. This part is suitable only for applications where reduced output current is acceptable.

Package Variant

SN74AHCT138DBR (Texas Instruments) uses 16-SSOP packaging (0.209", 5.30mm width) instead of 16-TSSOP. This variant requires PCB layout modification and is suitable only when 16-SSOP footprints are available.

Frequently Asked Questions (FAQ)

Q: Can I directly replace 74VHCT138AMTC with any of these substitutes?

A: Direct replacement is possible with parts maintaining identical electrical specifications: 8mA output current, 4.5V to 5.5V supply, and 16-TSSOP packaging. MC74VHCT138ADTRG and SN74AHCT138PWR are primary candidates. Parts with different output current ratings (4mA or 12mA) or extended temperature ranges require circuit verification.

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

A: These represent different logic families with varying electrical characteristics. 74VHCT and 74AHCT deliver 8mA output current. 74HCT delivers 4mA. 74LV delivers 12mA. All operate within the 4.5V to 5.5V supply range. Series selection depends on output drive requirements and temperature range needs.

Q: Why is the original 74VHCT138AMTC obsolete?

A: Obsolescence reflects manufacturer discontinuation. Active alternatives from onsemi (MC74VHCT138ADTRG), Texas Instruments (SN74AHCT138PWR, CAHCT138QPWRG4Q1), NXP Semiconductors (74AHCT138PW,118), Nexperia (74AHCT138PW-Q100J), and Diodes Incorporated (74AHCT138T16-13) provide equivalent functionality with ongoing production support.

Q: Does package type affect substitution?

A: Yes. The original uses 16-TSSOP (0.173", 4.40mm width). Most substitutes maintain this package. SN74AHCT138DBR uses 16-SSOP (0.209", 5.30mm width), requiring PCB footprint modification. Verify PCB layout compatibility before selecting package variants.

Q: Are all substitutes RoHS3 compliant?

A: All listed substitutes maintain RoHS3 compliance and MSL 1 (unlimited moisture sensitivity) ratings, matching the original part's environmental certifications.

Q: Which substitute offers the broadest temperature coverage?

A: SN74AHCT138MPWREP, MC74VHCT138ADTRG, and CAHCT138QPWRG4Q1 all provide -55°C to 125°C operating range, compared to the original -40°C to 85°C. Select based on application temperature requirements and long-term availability needs.

Q: Can I use SN74LV138ATPW as a direct replacement?

A: SN74LV138ATPW is functionally compatible but delivers 12mA output current versus the original 8mA. This enhanced drive capability is suitable for applications requiring higher output current. However, this part is classified as last-time-buy; verify long-term availability before design commitment.

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