1SMA12AT3 Equivalent & Substitute Parts

Part Overview

The 1SMA12AT3 is a unidirectional transient voltage suppressor (TVS) diode manufactured by onsemi, designed for general-purpose overvoltage protection in surface-mount applications. This component features a 12V reverse standoff voltage with a 19.9V maximum clamping voltage and 20.1A peak pulse current capability in a DO-214AC (SMA) package. The part is classified as obsolete, making identification of active equivalent and substitute components essential for ongoing design support and procurement.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	12	V
Voltage - Breakdown (Min)	13.3	V
Voltage - Clamping (Max) @ Ipp	19.9	V
Current - Peak Pulse (10/1000µs)	20.1	A
Power - Peak Pulse	400	W
Package / Case	DO-214AC, SMA	—
Operating Temperature	-65°C ~ 150°C	TJ
Mounting Type	Surface Mount	—
Type	Zener	—
Unidirectional Channels	1	—

Substitute Part Grouping Explanation

Substitution of the 1SMA12AT3 is determined by strict equivalence across the following electrical and mechanical parameters:

Primary Substitution Criteria:

Voltage - Reverse Standoff (Typ): 12V
Voltage - Breakdown (Min): 13.3V
Voltage - Clamping (Max) @ Ipp: 19.9V
Current - Peak Pulse (10/1000µs): 20.1A
Power - Peak Pulse: 400W
Package / Case: DO-214AC (SMA)
Unidirectional Channels: 1
Type: Zener

Substitute parts are grouped into two categories:

Direct Electrical Equivalents (Identical Clamping Voltage & Peak Current): Parts matching all primary electrical specifications with 19.9V clamping and 20.1A peak pulse current.

Functional Equivalents (Same Voltage Rating, Different Current/Power Ratings): Parts with identical 12V reverse standoff and 13.3V breakdown voltages but higher clamping voltages or peak pulse currents, suitable for applications requiring enhanced transient suppression capability within the same voltage class.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (Typ)	Voltage - Breakdown (Min)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Package / Case	Product Status	RoHS Status
1SMA12AT3	onsemi	12V	13.3V	19.9V	20.1A	400W	DO-214AC, SMA	Obsolete	RoHS non-compliant
SMAJ12A	Good-Ark Semiconductor	12V	13.3V	19.9V	20.1A	400W	DO-214AC, SMA	Active	ROHS3 Compliant
SMAJ12A-TR	STMicroelectronics	12V	13.3V	25.3V	91A (8/20µs)	400W	DO-214AC, SMA	Active	ROHS3 Compliant
PTVS12VS1UR,115	Nexperia USA Inc.	12V	13.3V	19.9V	20.1A	400W	SOD-123W	Active	ROHS3 Compliant
SM4T14AY	STMicroelectronics	12V	13.3V	25.3V	91A (8/20µs)	400W	DO-214AC, SMA	Active	ROHS3 Compliant
SMA6J12A-E3/61	Vishay General Semiconductor - Diodes Division	12V	13.3V	24.6V	157A (8/20µs)	4000W	DO-214AC, SMA	Active	ROHS3 Compliant
SMA6J12A-TP	Micro Commercial Co	12V	13.3V	19.9V	30.2A	600W	DO-214AC, SMA	Active	ROHS3 Compliant
SMA6J12A-TR	STMicroelectronics	12V	13.3V	24.6V	157A (8/20µs)	600W	DO-214AC, SMA	Active	ROHS3 Compliant
SMA6L12A	Littelfuse Inc.	12V	13.3V	19.9V	30.2A	600W	DO-221AC, SMA Flat Leads	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Replacement (Identical Electrical Performance):

SMAJ12A (Good-Ark Semiconductor) provides the closest direct replacement for the 1SMA12AT3. This part matches all electrical specifications exactly: 12V reverse standoff, 13.3V breakdown, 19.9V clamping voltage, and 20.1A peak pulse current in the same DO-214AC (SMA) package. The part is active and ROHS3 compliant, addressing the obsolescence and compliance limitations of the original component.

SMA6J12A-TP (Micro Commercial Co) offers identical electrical performance with enhanced current handling (30.2A vs. 20.1A) and higher power dissipation (600W vs. 400W) while maintaining the same 19.9V clamping voltage. This part is suitable for applications requiring additional margin in transient suppression capability.

Package Consideration:

PTVS12VS1UR,115 (Nexperia USA Inc.) matches the electrical specifications of the 1SMA12AT3 but uses a SOD-123W package instead of DO-214AC (SMA). This part is automotive-qualified (AEC-Q101) and suitable only for designs where package footprint compatibility is not a constraint.

Enhanced Performance Alternatives:

SMA6J12A-E3/61 (Vishay General Semiconductor) and SMA6J12A-TR (STMicroelectronics) provide higher clamping voltages (24.6V) and significantly higher peak pulse currents (157A) with substantially increased power dissipation (4000W and 600W respectively). These parts are suitable for applications requiring enhanced transient suppression beyond the original specification.

All recommended active substitutes are ROHS3 compliant and carry current product status, ensuring long-term availability and supply chain stability.

Frequently Asked Questions (FAQ)

Q: Can SMAJ12A directly replace the 1SMA12AT3 without circuit modification?

A: Yes. SMAJ12A matches all electrical parameters of the 1SMA12AT3: 12V reverse standoff, 13.3V breakdown voltage, 19.9V clamping voltage, 20.1A peak pulse current, and 400W power dissipation. The DO-214AC (SMA) package is identical. No circuit modification is required.

Q: What is the difference between SMAJ12A and SMA6J12A-TP?

A: Both parts share the same 12V reverse standoff and 19.9V clamping voltage. SMA6J12A-TP provides higher peak pulse current (30.2A vs. 20.1A) and power dissipation (600W vs. 400W), offering additional transient suppression margin. Both use the DO-214AC (SMA) package.

Q: Why do some substitutes have higher clamping voltages (24.6V or 25.3V)?

A: Parts such as SMA6J12A-TR and SMAJ12A-TR maintain the same 12V reverse standoff voltage but exhibit higher clamping voltages due to different semiconductor design. These parts are suitable for applications where the circuit can tolerate higher transient voltage peaks while maintaining the same standoff protection threshold.

Q: Is PTVS12VS1UR,115 compatible with the 1SMA12AT3 footprint?

A: No. PTVS12VS1UR,115 uses a SOD-123W package, which has a different footprint than the DO-214AC (SMA) package of the 1SMA12AT3. PCB layout modification is required for this substitution.

Q: Are all recommended substitutes RoHS compliant?

A: Yes. All active substitute parts listed are ROHS3 compliant, addressing the RoHS non-compliance status of the obsolete 1SMA12AT3.

Q: What is the operating temperature range difference between substitutes?

A: The 1SMA12AT3 operates from -65°C to 150°C. Most substitutes operate from -55°C to 150°C or -55°C to 175°C. Verify the specific operating temperature requirement of your application before selection.

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