1SMA20AT3 Equivalent & Substitute Parts

Part Overview

The 1SMA20AT3 is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by onsemi, rated for 20V reverse standoff voltage with a 32.4V maximum clamping voltage at peak pulse current of 12.3A. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

TVS diodes in the 20V class are widely used for transient protection in general-purpose applications requiring surface-mount SMA (DO-214AC) packaging. The obsolete status of the 1SMA20AT3 necessitates identification of functionally equivalent alternatives from active manufacturers.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	20	V
Voltage - Breakdown (Min)	22.2	V
Voltage - Clamping (Max) @ Ipp	32.4	V
Current - Peak Pulse (10/1000µs)	12.3	A
Power - Peak Pulse	400	W
Package / Case	DO-214AC, SMA	—
Operating Temperature Range	-65°C ~ 150°C	TJ
Type	Zener	—
Unidirectional Channels	1	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the 1SMA20AT3 is determined by strict equivalence across the following electrical and mechanical parameters:

Voltage - Reverse Standoff (Typ): 20V
Voltage - Breakdown (Min): 22.2V
Voltage - Clamping (Max) @ Ipp: 32.4V
Current - Peak Pulse (10/1000µs): 12.3A
Power - Peak Pulse: 400W
Package / Case: DO-214AC, SMA
Type: Zener, Unidirectional

Substitute parts are categorized into two groups:

Direct Equivalents maintain all critical electrical parameters (20V standoff, 32.4V clamping, 12.3A peak pulse, 400W power) and identical SMA packaging. These parts are pin-compatible and electrically interchangeable.

Similar Alternatives share the same 20V standoff and 22.2V breakdown voltages but differ in clamping voltage, peak pulse current, or power dissipation. These parts are suitable only when the application can tolerate higher clamping voltages or different current ratings.

Parameter Comparison

Manufacturer 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
1SMA20AT3	onsemi	20V	22.2V	32.4V	12.3A	400W	DO-214AC, SMA	Obsolete	RoHS non-compliant
SMAJ20A	MDD	20V	22.2V	32.4V	12.3A	400W	DO-214AC, SMA	Active	ROHS3 Compliant
SMAJ20A-13-F	Diodes Incorporated	20V	22.2V	32.4V	12.3A	400W	DO-214AC, SMA	Active	ROHS3 Compliant
SMAJ20A-TP	Micro Commercial Co	20V	22.2V	32.4V	12.3A	400W	DO-214AC, SMA	Active	ROHS3 Compliant
PTVS20VS1UR,115	Nexperia USA Inc.	20V	22.2V	32.4V	12.3A	400W	SOD-123W	Active	ROHS3 Compliant
SM4T23AY	STMicroelectronics	20V	22.2V	42.8V	54A (8/20µs)	400W	DO-214AC, SMA	Active	ROHS3 Compliant
SMA6J20A-E3/5A	Vishay General Semiconductor - Diodes Division	20V	22.2V	36.8V	93A (8/20µs)	4000W	DO-214AC, SMA	Active	ROHS3 Compliant
SMA6J20A-E3/61	Vishay General Semiconductor - Diodes Division	20V	22.2V	36.8V	93A (8/20µs)	4000W	DO-214AC, SMA	Active	ROHS3 Compliant
SMA6J20A-TR	STMicroelectronics	20V	22.2V	36.8V	93A (8/20µs)	600W	DO-214AC, SMA	Active	ROHS3 Compliant
SM15T24A	STMicroelectronics	20.5V	22.8V	42.8V	234A (8/20µs)	1500W	DO-214AB, SMC	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Equivalents (Recommended for Pin-Compatible Replacement)

SMAJ20A (MDD), SMAJ20A-13-F (Diodes Incorporated), and SMAJ20A-TP (Micro Commercial Co) are electrically and mechanically identical to the 1SMA20AT3. All three are active products with ROHS3 compliance, providing immediate obsolescence mitigation. Selection among these three should be based on availability, lead time, and procurement channel preference.

Package Variant (Electrical Equivalent, Different Package)

PTVS20VS1UR,115 (Nexperia USA Inc.) maintains identical electrical specifications but uses SOD-123W packaging instead of SMA. This part is suitable only if the PCB layout can accommodate the different footprint. The part carries AEC-Q101 automotive qualification.

Higher Performance Alternatives (Electrical Differences)

SMA6J20A-E3/5A and SMA6J20A-E3/61 (Vishay) and SMA6J20A-TR (STMicroelectronics) share the same 20V standoff voltage but feature higher clamping voltage (36.8V), significantly higher peak pulse current (93A), and substantially higher power dissipation (4000W or 600W). These parts are suitable for applications requiring enhanced transient suppression capability but are not direct replacements due to different electrical characteristics.

SM4T23AY (STMicroelectronics) and SM15T24A (STMicroelectronics) represent higher-performance classes with increased clamping voltages and peak pulse currents. SM15T24A uses SMC packaging (DO-214AB) rather than SMA, requiring PCB redesign.

Compliance Considerations

The 1SMA20AT3 is RoHS non-compliant. All recommended direct equivalents and alternatives are ROHS3 compliant, supporting modern supply chain requirements.

Frequently Asked Questions (FAQ)

Q: Can SMAJ20A directly replace 1SMA20AT3 without circuit modification?

A: Yes. SMAJ20A maintains identical electrical parameters (20V standoff, 32.4V clamping, 12.3A peak pulse, 400W power) and SMA packaging. No circuit or PCB modifications are required.

Q: What is the difference between SMAJ20A-TP and SMAJ20A-13-F?

A: Both are electrically identical direct equivalents. The difference is in manufacturer (Micro Commercial Co versus Diodes Incorporated) and packaging format (Tape & Reel versus Cut Tape & Digi-Reel). Selection depends on procurement preference and availability.

Q: Why do SMA6J20A variants have different electrical specifications?

A: SMA6J20A variants are designed for higher transient energy absorption, featuring 36.8V clamping voltage and 93A peak pulse current compared to the 1SMA20AT3's 32.4V and 12.3A. These are suitable only for applications requiring enhanced protection, not as direct replacements.

Q: Can PTVS20VS1UR,115 be used as a direct replacement?

A: PTVS20VS1UR,115 is electrically equivalent but uses SOD-123W packaging instead of SMA. Direct substitution requires PCB footprint modification. Use only if layout changes are feasible.

Q: What is the significance of RoHS compliance in selecting a substitute?

A: RoHS3 compliance is required for modern electronics manufacturing and supply chain acceptance. All active substitute parts listed are ROHS3 compliant, whereas the obsolete 1SMA20AT3 is non-compliant. Compliance status should be verified with your procurement and quality requirements.

Q: Are there any temperature range differences between direct equivalents?

A: SMAJ20A-TP extends to -55°C to 175°C (TA), while SMAJ20A and SMAJ20A-13-F operate to -55°C to 150°C (TJ). The 1SMA20AT3 operates to -65°C to 150°C (TJ). Verify temperature requirements for your application before selection.

Q: What packaging formats are available for 20V TVS diodes in this class?

A: Direct equivalents use DO-214AC (SMA) packaging. PTVS20VS1UR,115 uses SOD-123W. Higher-performance variants use SMA or SMC (DO-214AB) packages. Confirm PCB footprint compatibility before ordering.

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