SMAJ30 Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The SMAJ30 is a unidirectional Zener-type transient voltage suppressor manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. The device features a 30V reverse standoff voltage with a 50.82V maximum clamping voltage at peak pulse current, housed in a DO-214AC (SMA) package. The SMAJ30 is classified as obsolete; therefore, identifying functionally equivalent active alternatives is essential for design continuity and procurement reliability.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	30	V
Voltage - Breakdown (Min)	31.55	V
Voltage - Clamping (Max) @ Ipp	50.82	V
Current - Peak Pulse (10/1000µs)	8.3	A
Power - Peak Pulse	400	W
Operating Temperature Range	-65 to 150	°C (TJ)
Package / Case	DO-214AC, SMA	—
Type	Zener	—
Unidirectional Channels	1	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution eligibility for the SMAJ30 is determined by the following critical parameters:

Voltage - Reverse Standoff (Typ): Must be 30V
Package / Case: Must be DO-214AC (SMA)
Type: Must be Zener
Unidirectional Channels: Must be 1
Mounting Type: Must be Surface Mount
RoHS Status: Must be ROHS3 Compliant

Substitute parts are grouped into two categories based on clamping voltage performance:

Category A - Standard Clamping (48.4V): Parts with clamping voltage at or below 50.82V, maintaining electrical compatibility with the original design intent.

Category B - Enhanced Clamping (54.6V - 64.3V): Parts with higher clamping voltages, suitable for applications requiring additional transient suppression margin but requiring design verification.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (V)	Voltage - Breakdown Min (V)	Voltage - Clamping Max @ Ipp (V)	Current - Peak Pulse (A)	Power - Peak Pulse (W)	Operating Temp (°C)	Package	Status
SMAJ30	Littelfuse Inc.	30	31.55	50.82	8.3	400	-65 to 150	DO-214AC (SMA)	Obsolete
SMAJ30A	MDD	30	33.3	48.4	8.3	400	-50 to 150	DO-214AC (SMA)	Active
SZ1SMA30AT3G	Littelfuse Inc.	30	33.3	48.4	8.3	400	-65 to 150	DO-214AC (SMA)	Active
SMAJ30A-13-F	Diodes Incorporated	30	33.3	48.4	8.3	400	-55 to 150	DO-214AC (SMA)	Active
SMAJ30A-TP	Micro Commercial Co	30	33.3	48.4	8.3	400	-55 to 175	DO-214AC (SMA)	Active
SMAJ30AE3/TR13	Microchip Technology	30	33.3	48.4	10.3	500	-65 to 150	DO-214AC (SMA)	Active
SMAJ30E3/TR13	Microchip Technology	30	33.3	54.6	9.3	500	-65 to 150	DO-214AC (SMA)	Active
SM4T35AY	STMicroelectronics	30	33.3	64.3	36 (8/20µs)	400	-55 to 150	DO-214AC (SMA)	Active
SMAJ30A-TR	STMicroelectronics	30	33.3	64.3	36 (8/20µs)	400	-55 to 150	DO-214AC (SMA)	Active
TV04A300J-G	Comchip Technology	30	33.3	48.4	8.26	400	-55 to 150	DO-214AC (SMA)	Active

Engineering Selection Recommendations

Primary Recommendation - Category A (Standard Clamping)

For direct replacement with minimal design impact, select from parts with 48.4V clamping voltage:

SZ1SMA30AT3G (Littelfuse Inc.): Maintains original manufacturer continuity. Preserves full temperature range (-65 to 150°C). AEC-Q101 automotive qualification provides enhanced reliability documentation. Tape & Reel packaging supports production automation.
SMAJ30A-13-F (Diodes Incorporated): Active status with established supply chain. Cut Tape & Digi-Reel packaging options accommodate various procurement workflows. REACH compliant.
SMAJ30A-TP (Micro Commercial Co): Extended upper operating temperature to 175°C provides thermal margin for high-ambient applications. Tape & Reel packaging standard.

Secondary Recommendation - Category B (Enhanced Clamping)

For applications requiring additional transient suppression margin:

SMAJ30E3/TR13 (Microchip Technology): 54.6V clamping with 9.3A peak pulse current. 500W peak power rating. Maintains -65 to 150°C temperature range. Suitable for circuits with tighter voltage tolerance requirements.
SM4T35AY or SMAJ30A-TR (STMicroelectronics): 64.3V clamping with significantly higher peak pulse current (36A at 8/20µs). AEC-Q101 automotive qualification. Recommended only when circuit design explicitly requires enhanced transient suppression beyond original SMAJ30 specifications.

Enhanced Performance Option

SMAJ30AE3/TR13 (Microchip Technology): 48.4V clamping with elevated peak pulse current (10.3A) and 500W power rating. Provides performance headroom while maintaining voltage compatibility. Full temperature range support.

All recommended substitutes are ROHS3 compliant and MSL 1 rated, ensuring compatibility with standard manufacturing and storage protocols.

Frequently Asked Questions (FAQ)

Q: Can I use SM4T35AY or SMAJ30A-TR as direct replacements for SMAJ30?

A: These parts meet the core substitution criteria (30V standoff, DO-214AC package, Zener type, single channel). However, their 64.3V clamping voltage is significantly higher than the original 50.82V. Use only if circuit design has been verified to tolerate the higher clamping voltage. The 36A peak pulse current (8/20µs) differs from the original 8.3A (10/1000µs) specification, requiring pulse waveform compatibility assessment.

Q: What is the difference between SMAJ30AE3/TR13 and SMAJ30E3/TR13?

A: Both are Microchip Technology products in DO-214AC (SMA) packages with -65 to 150°C operating range. SMAJ30AE3/TR13 provides 48.4V clamping with 10.3A peak pulse and 500W power. SMAJ30E3/TR13 provides 54.6V clamping with 9.3A peak pulse and 500W power. Select based on required clamping voltage for your circuit protection threshold.

Q: Why does SZ1SMA30AT3G have AEC-Q101 qualification while others do not list it?

A: AEC-Q101 is an automotive-grade qualification indicating enhanced reliability testing and traceability. SZ1SMA30AT3G explicitly lists this qualification. Other parts may meet equivalent standards but do not explicitly declare automotive qualification in the provided specifications. Verify qualification requirements with your application standards.

Q: Can I substitute SMAJ30A (MDD) for SMAJ30?

A: Yes, SMAJ30A meets all core substitution criteria. However, its operating temperature range is -50 to 150°C, which is 15°C narrower at the lower end compared to the original -65 to 150°C. Verify that your application does not require operation below -50°C.

Q: What packaging options are available for these substitutes?

A: Substitute parts are available in Tape & Reel (TR), Cut Tape (CT) & Digi-Reel, and bulk packaging. Tape & Reel is standard for automated assembly. Cut Tape & Digi-Reel accommodates lower-volume or mixed-component procurement. Verify packaging availability with your supplier before design finalization.

Q: Are all substitutes RoHS3 compliant?

A: Yes, all listed substitute parts are ROHS3 compliant and MSL 1 rated, meeting standard environmental and moisture sensitivity requirements for surface-mount assembly.

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