SMAJ12 Equivalent & Substitute Parts

Part Overview

The SMAJ12 is a unidirectional transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. This component features a 12V reverse standoff voltage, 20.9V maximum clamping voltage, and 400W peak pulse power rating in a DO-214AC (SMA) package. The SMAJ12 is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain electrical compatibility across voltage ratings, current handling, and thermal specifications while supporting the same surface-mount package format.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	12	V
Voltage - Breakdown (Min)	12.6	V
Voltage - Clamping (Max) @ Ipp	20.9	V
Current - Peak Pulse (10/1000µs)	20.1	A
Power - Peak Pulse	400	W
Operating Temperature Range	-65°C ~ 150°C	TJ
Package / Case	DO-214AC, SMA	—
Mounting Type	Surface Mount	—
Type	Zener	—
Unidirectional Channels	1	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution eligibility for the SMAJ12 is determined by the following critical parameters:

Mandatory Matching Criteria:

Voltage - Reverse Standoff (Typ): 12V
Package / Case: DO-214AC, SMA
Mounting Type: Surface Mount
Type: Zener
Unidirectional Channels: 1

Allowable Variation Ranges:

Voltage - Clamping (Max) @ Ipp: 19.9V to 24.6V (original: 20.9V)
Current - Peak Pulse (10/1000µs): 20.1A to 157A (original: 20.1A)
Power - Peak Pulse: 400W to 4000W (original: 400W)
Operating Temperature Range: -65°C to -55°C minimum; 150°C to 175°C maximum
Voltage - Breakdown (Min): 12.6V to 13.3V (original: 12.6V)

All substitute parts identified maintain the 12V standoff voltage and DO-214AC SMA package format. Variations in clamping voltage, peak pulse current, and power dissipation reflect different manufacturer specifications while preserving functional compatibility for general-purpose transient suppression applications.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (Typ)	Voltage - Breakdown (Min)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Operating Temperature	Product Status
SMAJ12	Littelfuse Inc.	12V	12.6V	20.9V	20.1A	400W	-65°C ~ 150°C (TJ)	Obsolete
SMAJ12A	Good-Ark Semiconductor	12V	13.3V	19.9V	20.1A	400W	-55°C ~ 150°C (TJ)	Active
SMA6J12A-E3/61	Vishay General Semiconductor - Diodes Division	12V	13.3V	24.6V	157A (8/20µs)	4000W	-55°C ~ 150°C (TJ)	Active
SMA6J12A-TP	Micro Commercial Co	12V	13.3V	19.9V	30.2A	600W	-55°C ~ 175°C (TA)	Active
SMA6J12A-TR	STMicroelectronics	12V	13.3V	24.6V	157A (8/20µs)	600W	-55°C ~ 175°C (TJ)	Active
SMAJ12A-13-F	Diodes Incorporated	12V	13.3V	19.9V	20.1A	400W	-55°C ~ 150°C (TJ)	Active
SMAJ12A-TP	Micro Commercial Co	12V	13.3V	19.9V	20.1A	400W	-55°C ~ 175°C (TA)	Active
SMAJ12AE3/TR13	Microchip Technology	12V	13.3V	19.9V	25.1A	500W	-65°C ~ 150°C (TJ)	Active
SMAJ12E3/TR13	Microchip Technology	12V	13.3V	22V	22.7A	500W	-65°C ~ 150°C (TJ)	Active

Engineering Selection Recommendations

All identified substitute parts are classified as Active products, ensuring ongoing availability and manufacturer support. The SMAJ12 (Obsolete) requires replacement with an active equivalent for new production and long-term supply chain continuity.

Compliance & Certification: All substitute parts maintain ROHS3 compliance and Moisture Sensitivity Level 1 (Unlimited), matching the original SMAJ12 specifications. REACH status is unaffected for all active substitutes.

Selection Basis:

Direct Electrical Match: SMAJ12A (Good-Ark Semiconductor), SMAJ12A-13-F (Diodes Incorporated), and SMAJ12A-TP (Micro Commercial Co) provide identical 12V standoff voltage, 19.9V clamping voltage, 20.1A peak pulse current, and 400W power rating. These parts are functionally equivalent to the original SMAJ12.
Enhanced Performance Options: SMA6J12A-E3/61 (Vishay) and SMA6J12A-TR (STMicroelectronics) offer higher current handling (157A) and power dissipation (4000W and 600W respectively), suitable for applications requiring greater transient suppression capability.
Temperature Range Considerations: SMAJ12AE3/TR13 and SMAJ12E3/TR13 (Microchip Technology) maintain the original -65°C minimum operating temperature, matching extended low-temperature requirements. SMA6J12A-TP and SMA6J12A-TR extend the maximum operating temperature to 175°C.

Frequently Asked Questions (FAQ)

Q: Can SMAJ12A directly replace the obsolete SMAJ12? A: Yes. SMAJ12A (Good-Ark Semiconductor) provides direct electrical equivalence with identical 12V standoff voltage, 19.9V clamping voltage, 20.1A peak pulse current, and 400W power rating in the same DO-214AC SMA package.

Q: What is the difference between 19.9V and 24.6V clamping voltage options? A: Clamping voltage determines the maximum voltage the TVS diode allows across its terminals during a transient event. The 19.9V variants (SMAJ12A, SMAJ12A-13-F, SMAJ12A-TP) clamp closer to the original SMAJ12 specification (20.9V). The 24.6V variants (SMA6J12A-E3/61, SMA6J12A-TR) provide slightly higher clamping voltage, suitable for applications with higher transient voltage tolerance.

Q: Are all substitute parts available in the same packaging format? A: Yes. All substitute parts use DO-214AC (SMA) surface-mount package format, maintaining PCB layout and assembly compatibility with the original SMAJ12.

Q: Which substitute offers the best thermal performance? A: SMA6J12A-TP and SMA6J12A-TR support operating temperatures up to 175°C, compared to 150°C for most other substitutes. These parts are suitable for high-temperature applications.

Q: What is the significance of the peak pulse current rating difference? A: Peak pulse current (measured at 10/1000µs or 8/20µs waveforms) indicates the maximum transient current the diode can suppress. Higher ratings (157A for Vishay and STMicroelectronics variants) provide greater protection margin for high-energy transient events, while 20.1A to 30.2A ratings match or slightly exceed the original SMAJ12 specification.

Q: Are all substitutes RoHS3 compliant? A: Yes. All identified substitute parts maintain ROHS3 compliance and Moisture Sensitivity Level 1 (Unlimited), ensuring environmental and regulatory compatibility.

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