Is there a pin-compatible replacement for SN74HC138DR?

No, based on the reviewed candidates, there is no pin-compatible replacement for the SN74HC138DR. All functional alternatives require a PCB redesign due to different pinouts.

What risks should I check before replacing SN74HC138DR?

Before replacing, you must verify the pinout, logic function, and propagation delay. The primary risk is that alternatives are not pin-compatible and have different functions (e.g., dual 2:4 vs single 3:8), requiring a full board redesign.

SN74HC138DR Alternatives, Datasheet & Cross Reference | Texas Instruments

The SN74HC138DR is a popular 3-to-8 line decoder in a SOIC-16 package. While no direct drop-in replacements are available, several functional alternatives from the 74HC logic family exist for board redesigns.

AI replacement insight

Electrical riskhigh

Pinout and function are different. Using a substitute without redesign will cause circuit failure.

Package risklow

Several alternatives exist in the same SOIC-16 package, simplifying physical placement in a redesign.

Can it be replaced directly?

No direct, pin-compatible drop-in replacement for the SN74HC138DR has been identified. All alternatives require circuit and PCB layout modifications.

Best replacement path

For new designs or board revisions, consider a functional alternative like the SN74HC139DR, which provides two 2-to-4 decoders in the same package.

Main risk

The primary risk is pinout and functional incompatibility, which necessitates a board redesign and logic verification.

Recommended alternatives

Functional alternative in the same package, but requires redesign due to different pinout and logic configuration.

View details

Alternative comparison matrix

Feature / factor	SN74HC138DR	SN74HC139DR	SN74HC139QDRQ1	Compatibility / risk
Package	SOIC-16	SOIC-16	SOIC-16	SOIC-16 — Package matches, enabling form-fit consideration.; SN74HC139QDRQ1: Package matches, enabling form-fit consideration.
Function	Single 3-to-8 Decoder	Dual 2-to-4 Decoder	Dual 2-to-4 Decoder	Dual 2-to-4 Decoder — Different configuration; not a direct replacement.; SN74HC139QDRQ1: Different configuration; not a direct replacement.
Voltage	2 V to 6 V	2 V to 6 V	-	2 V to 6 V — Supply voltage range is identical.
Temperature	-40°C to 85°C	-40°C to 85°C	-40°C to 125°C	-40°C to 85°C / -40°C to 125°C — Operating temperature range is identical.; SN74HC139QDRQ1: Wider operating temperature range.
Pinout	Compatible	Not compatible	Not compatible	Not compatible — Pin functions do not align; requires PCB redesign.; SN74HC139QDRQ1: Pin functions do not align; requires PCB redesign.
Application	No	-	Yes (AEC-Q100)	Yes (AEC-Q100) — Automotive qualified, may be suitable for higher reliability needs.

Application & sourcing insights

Questions & answers

The best alternative depends on your design flexibility. If you can redesign the PCB, the SN74HC139DR is a related part from the same family. However, it is a dual 2-to-4 decoder and not a direct 3-to-8 decoder.