Is there a pin-compatible replacement for SMAJ40A?

SMAJ36A is a potential form-fit replacement in the same DO-214AC (SMA) package. However, its lower standoff voltage (36V vs 40V) is a critical difference that must be verified for your application.

What risks should I check before replacing SMAJ40A?

First, ensure the replacement is unidirectional. Second, verify the package (DO-214AC/SMA) and PCB footprint match. Third, confirm the reverse standoff voltage is >= 40V to avoid unintended clamping during normal operation.

SMAJ40A Alternatives, Datasheet & Cross Reference | BOURNS

The SMAJ40A is a 400W, 40V unidirectional TVS diode in a DO-214AC (SMA) package. When seeking alternatives, key considerations include matching the unidirectional polarity, package footprint, and ensuring the standoff voltage is at least 40V.

AI replacement insight

Electrical riskmedium

Candidates have different standoff voltages which must be verified.

Package riskhigh

Most functional alternatives are in different packages (SMB, SMC) and are not drop-in.

Can it be replaced directly?

No direct, fully-compatible replacement for SMAJ40A was identified. All candidates have critical differences in either electrical parameters or physical package.

Best replacement path

Parametric alternative (SMAJ36A) if the lower 36V standoff voltage is acceptable; otherwise, a functional alternate with a board redesign is necessary.

Main risk

The primary risks are package mismatch requiring a board redesign, or using a part with a lower standoff voltage that could fail in a 40V system.

Recommended alternatives

Form-fit alternate with a lower 36V standoff voltage. Requires electrical verification before use.

View details

Alternative comparison matrix

Feature / factor	SMAJ40A	SMAJ36A	SMBJ60A	SMCJ48A	Compatibility / risk
Package	DO-214AC (SMA)	DO-214AC (SMA)	DO-214AA (SMB)	DO-214AB (SMC)	DO-214AC (SMA) / DO-214AA (SMB) / DO-214AB (SMC) — Package is form-fit compatible.; SMBJ60A: Larger package requires PCB redesign.; SMCJ48A: Larger package requires PCB redesign.
Polarity Or Type	Unidirectional	Unidirectional	Unidirectional	Unidirectional	Unidirectional — Polarity matches.; SMBJ60A: Polarity matches.; SMCJ48A: Polarity matches.
Voltage V	40.0V	36.0V	60.0V	48.0V	36.0V / 60.0V / 48.0V — Lower standoff voltage is a risk.; SMBJ60A: Higher voltage provides more margin.; SMCJ48A: Higher voltage provides more margin.
Power W	400.0W	400.0W	600.0W	1500.0W	400.0W / 600.0W / 1500.0W — Power rating matches.; SMBJ60A: Higher power rating.; SMCJ48A: Significantly higher power rating.

Application & sourcing insights

Questions & answers

There are no direct drop-in replacements found. SMAJ36A has the same package but a lower 36V standoff voltage, requiring electrical review. Other parts like SMCJ48A are electrically superior but require a PCB layout change due to different packages.