1SMC20AT3 Transient Voltage Suppressor (TVS) Diode – Equivalent & Substitute Parts

Part Overview

The 1SMC20AT3 is a unidirectional Zener-type transient voltage suppressor diode manufactured by onsemi, designed for general-purpose overvoltage protection in surface-mount applications. The device features a 20V reverse standoff voltage with 32.4V maximum clamping voltage and 46.3A peak pulse current capability in a DO-214AB (SMC) package. The part is currently obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity.

Key Parameters

Parameter	Value
Voltage – Reverse Standoff (Typ)	20V
Voltage – Breakdown (Min)	22.2V
Voltage – Clamping (Max) @ Ipp	32.4V
Current – Peak Pulse (10/1000µs)	46.3A
Power – Peak Pulse	1500W (1.5kW)
Package / Case	DO-214AB, SMC
Mounting Type	Surface Mount
Operating Temperature Range	-65°C ~ 150°C (TJ)
Type	Zener, Unidirectional

Substitute Part Grouping Explanation

Substitution for the 1SMC20AT3 is determined by strict equivalence in the following electrical and mechanical parameters:

Voltage Rating: Reverse standoff voltage of 20V, breakdown minimum of 22.2V, and clamping voltage of 32.4V
Current Handling: Peak pulse current capability of 46.3A at 10/1000µs pulse duration
Power Dissipation: Peak pulse power of 1500W (1.5kW)
Package: DO-214AB (SMC) surface-mount package
Diode Type: Unidirectional Zener configuration

Substitute parts are grouped into two categories:

Category A – Direct Electrical Equivalents (46.3A @ 1500W): Parts with identical electrical specifications and 1500W power rating, maintaining the same current and power characteristics as the original 1SMC20AT3.

Category B – Enhanced Performance Alternatives (Higher Current/Power): Parts with the same voltage ratings and package but offering increased peak pulse current and power dissipation capabilities, suitable for applications requiring additional margin or higher transient energy absorption.

Parameter Comparison

Part Number	Manufacturer	Voltage – Reverse Standoff	Voltage – Clamping (Max)	Current – Peak Pulse	Power – Peak Pulse	Package	Product Status	RoHS Status
1SMC20AT3	onsemi	20V	32.4V	46.3A	1500W	DO-214AB (SMC)	Obsolete	Non-compliant
SMCJ20A-13-F	Diodes Incorporated	20V	32.4V	46.3A	1500W	DO-214AB (SMC)	Active	ROHS3 Compliant
SMCJ20A-HR	Littelfuse Inc.	20V	32.4V	46.3A	1500W	DO-214AB (SMC)	Active	ROHS3 Compliant
SMCJ20A-HRA	Littelfuse	20V	32.4V	46.3A	1500W	DO-214AB (SMC)	Active	ROHS3 Compliant
SMCJ20A	Fairchild Semiconductor	20V	32.4V	46.3A	1500W	DO-214AB (SMC)	Active	Not specified
3.0SMCJ20A-13	Diodes Incorporated	20V	32.4V	62.6A	3000W	DO-214AB (SMC)	Active	ROHS3 Compliant
5.0SMDJ20A	Taiwan Semiconductor Corporation	20V	32.4V	155A	5000W	DO-214AB (SMC)	Active	ROHS3 Compliant
5.0SMDJ20A-T7	Littelfuse Inc.	20V	32.4V	155A	5000W	DO-214AB (SMC)	Active	ROHS3 Compliant
LNBTVS4-222S	STMicroelectronics	20V	30V	334A (8/20µs)	22500W	DO-214AB (SMC)	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Replacement (Category A – Electrical Equivalents)

For applications requiring exact electrical and power specifications matching the 1SMC20AT3, the following active parts provide direct substitution:

SMCJ20A-13-F (Diodes Incorporated): Active product with ROHS3 compliance, identical 46.3A / 1500W specifications, available in Tape & Reel packaging with 35,400 units in stock.
SMCJ20A-HR (Littelfuse Inc.): Active product with ROHS3 compliance, identical electrical specifications, extended operating temperature range (-65°C ~ 150°C), available in Tape & Reel with 939 units in stock.
SMCJ20A-HRA (Littelfuse): Active product with ROHS3 compliance, identical electrical specifications, extended operating temperature range (-65°C ~ 150°C), available in Tape & Reel with 739 units in stock.
SMCJ20A (Fairchild Semiconductor): Active product with identical 46.3A / 1500W specifications, available in bulk packaging with 23,864 units in stock.

Enhanced Performance Alternatives (Category B – Higher Current/Power)

For applications where increased transient energy absorption or design margin is beneficial:

3.0SMCJ20A-13 (Diodes Incorporated): 62.6A / 3000W capability, ROHS3 compliant, active status, 71,647 units in stock.
5.0SMDJ20A (Taiwan Semiconductor Corporation): 155A / 5000W capability, ROHS3 compliant, active status, 15,200 units in stock.
5.0SMDJ20A-T7 (Littelfuse Inc.): 155A / 5000W capability, ROHS3 compliant, active status, extended temperature range (-65°C ~ 150°C), 1,683 units in stock.
LNBTVS4-222S (STMicroelectronics): 334A / 22500W capability (8/20µs pulse), ROHS3 compliant, active status, 3,060 units in stock.

All substitute parts maintain the DO-214AB (SMC) package and surface-mount configuration. Selection should prioritize active products with ROHS3 compliance for new designs.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with higher peak pulse current than the 1SMC20AT3?

A: Yes. Parts with higher current ratings (62.6A, 155A, or 334A) are electrically compatible substitutes provided they maintain the same voltage ratings (20V reverse standoff, 32.4V clamping). Higher current capability provides additional design margin and does not create compatibility issues in the circuit.

Q: What is the difference between the SMCJ20A variants (SMCJ20A-HR, SMCJ20A-HRA, SMCJ20A-13-F)?

A: All three maintain identical electrical specifications (20V / 32.4V / 46.3A / 1500W). Differences are in packaging format (Tape & Reel vs. Bulk), manufacturer (Littelfuse vs. Diodes Incorporated), and inventory availability. The "-HR" and "-HRA" designations indicate Littelfuse high-reliability series variants with extended temperature range support (-65°C ~ 150°C).

Q: Is the 1SMC20AT3 still available for purchase?

A: The 1SMC20AT3 is obsolete. However, 3,550 units are reported in stock as new original inventory. For long-term production continuity, migration to an active substitute part is recommended.

Q: Are all substitute parts RoHS compliant?

A: Most active substitutes listed are ROHS3 compliant. The original 1SMC20AT3 is RoHS non-compliant. The SMCJ20A (Fairchild Semiconductor) does not specify RoHS status. For applications requiring RoHS compliance, select from Diodes Incorporated, Littelfuse, Taiwan Semiconductor Corporation, or STMicroelectronics alternatives.

Q: Can I use the LNBTVS4-222S as a direct replacement?

A: The LNBTVS4-222S maintains the same 20V reverse standoff voltage and DO-214AB package but has a 30V maximum clamping voltage (versus 32.4V) and significantly higher current/power ratings (334A / 22500W). It is electrically compatible for overvoltage protection but represents a higher-performance alternative rather than a direct equivalent.

Q: What packaging options are available for substitute parts?

A: Substitute parts are available in Tape & Reel (TR) and Bulk packaging formats. All maintain the DO-214AB (SMC) surface-mount package. Selection of packaging format depends on production volume and assembly requirements.

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