1SMB20AT3 Equivalent & Substitute Parts

Part Overview

The 1SMB20AT3 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 20V reverse standoff voltage with a 32.4V maximum clamping voltage and 18.5A peak pulse current capability in a DO-214AA (SMB) package. The part is currently obsolete, making equivalent substitutes necessary for new designs and ongoing production support.

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)	18.5	A
Power - Peak Pulse	600	W
Package / Case	DO-214AA, SMB	—
Operating Temperature Range	-65 to 150	°C (TJ)
Type	Zener	—
Unidirectional Channels	1	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the 1SMB20AT3 is determined by strict electrical and mechanical parameter matching:

Critical Matching Parameters:

Voltage - Reverse Standoff: 20V (typ)
Voltage - Breakdown (Min): 22.2V
Voltage - Clamping (Max) @ Ipp: 32.4V
Current - Peak Pulse (10/1000µs): 18.5A minimum
Power - Peak Pulse: 600W
Package / Case: DO-214AA (SMB)
Unidirectional Channels: 1
Type: Zener

All substitute parts listed maintain these electrical specifications within the defined tolerances. Package compatibility (DO-214AA/SMB) ensures direct mechanical and electrical interchangeability on printed circuit boards. Operating temperature range variations are noted but do not prevent substitution where the application temperature remains within the substitute part's specified range.

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	Operating Temperature	Product Status	RoHS Status
1SMB20AT3	onsemi	20V	22.2V	32.4V	18.5A	600W	DO-214AA, SMB	-65 to 150°C (TJ)	Obsolete	RoHS non-compliant
SMBJ20A	Good-Ark Semiconductor	20V	22.2V	32.4V	18.5A	600W	DO-214AA, SMB	-55 to 150°C (TJ)	Active	ROHS3 Compliant
SMBJ20A-TR	STMicroelectronics	20V	22.2V	32.4V	19.4A	600W	DO-214AA, SMB	-55 to 150°C (TJ)	Active	ROHS3 Compliant
SMBJ20A/54	Vishay General Semiconductor - Diodes Division	20V	22.2V	32.4V	18.5A	600W	DO-214AA, SMB	-55 to 150°C (TJ)	Active	RoHS non-compliant
PTVS20VP1UP,115	NXP USA Inc.	20V	22.2V	32.4V	18.5A	600W	SOD-128	-55 to 150°C (TA)	Active	Not specified
SMBJ20A-13-F	Diodes Incorporated	20V	22.2V	32.4V	18.5A	600W	DO-214AA, SMB	-55 to 150°C (TJ)	Active	ROHS3 Compliant
SMBJ20A-HR	Littelfuse Inc.	20V	22.2V	32.4V	18.6A	600W	DO-214AA, SMB	-65 to 150°C (TJ)	Active	ROHS3 Compliant
SMBJ20A-HRA	Littelfuse Inc.	20V	22.2V	32.4V	18.6A	600W	DO-214AA, SMB	-65 to 150°C (TJ)	Active	ROHS3 Compliant
SMBJ20A-TP	Micro Commercial Co	20V	22.2V	32.4V	18.5A	600W	DO-214AA, SMB	-55 to 175°C (TJ)	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct SMB Package Substitutes (Recommended Primary Options):

SMBJ20A variants from Good-Ark Semiconductor, STMicroelectronics, Diodes Incorporated, Littelfuse, and Micro Commercial Co provide full electrical equivalence with active product status. These parts maintain the 20V reverse standoff, 22.2V minimum breakdown, and 32.4V clamping specifications. Selection among these options should prioritize ROHS3 compliance for new designs. The Littelfuse SMBJ20A-HR and SMBJ20A-HRA variants extend the lower operating temperature limit to -65°C, matching the original 1SMB20AT3 specification.

Alternative Package Consideration:

The PTVS20VP1UP,115 from NXP USA Inc. (Nexperia) provides electrical equivalence but uses a SOD-128 package instead of DO-214AA (SMB). This part is suitable only for applications where PCB layout permits SOD-128 footprint substitution. The automotive-grade qualification (AEC-Q101) provides additional reliability assurance for demanding environments.

Compliance Considerations:

The original 1SMB20AT3 is RoHS non-compliant and obsolete. For new production, ROHS3-compliant alternatives (SMBJ20A from Good-Ark, STMicroelectronics, Diodes Incorporated, Littelfuse, and Micro Commercial Co) are preferred. The Vishay SMBJ20A/54 maintains RoHS non-compliance status, matching the original specification if legacy compliance requirements apply.

Frequently Asked Questions (FAQ)

Q: Can SMBJ20A variants be used as direct replacements for 1SMB20AT3?

A: Yes. All SMBJ20A variants listed maintain identical electrical specifications (20V standoff, 22.2V breakdown, 32.4V clamping, 18.5A peak pulse, 600W peak power) and use the same DO-214AA (SMB) package. They are electrically and mechanically interchangeable.

Q: What is the difference between SMBJ20A-HR and SMBJ20A-HRA?

A: Both parts from Littelfuse are electrically identical with matching specifications. The designation difference reflects internal product line organization. Both are ROHS3 compliant and support the extended -65 to 150°C operating temperature range.

Q: Why is PTVS20VP1UP,115 listed as a similar part rather than a direct substitute?

A: The PTVS20VP1UP,115 uses a SOD-128 package instead of DO-214AA (SMB). While electrical specifications are equivalent, the different package footprint requires PCB layout modification. It is suitable only when package change is acceptable.

Q: Does operating temperature range affect substitution eligibility?

A: Operating temperature range affects substitution only if the application requires operation outside the substitute part's specified range. For applications operating within -55 to 150°C, all listed SMBJ20A variants are suitable. For applications requiring -65°C operation, select Littelfuse SMBJ20A-HR, SMBJ20A-HRA, or onsemi alternatives.

Q: Are there RoHS compliance differences among the substitute parts?

A: Yes. Good-Ark Semiconductor, STMicroelectronics, Diodes Incorporated, Littelfuse, and Micro Commercial Co variants are ROHS3 compliant. The Vishay SMBJ20A/54 is RoHS non-compliant, matching the original 1SMB20AT3 status. For new designs, ROHS3-compliant options are recommended.

Q: What is the peak pulse current specification tolerance among substitutes?

A: Most substitutes specify 18.5A peak pulse current, matching the original 1SMB20AT3. The STMicroelectronics SMBJ20A-TR and Littelfuse variants (SMBJ20A-HR, SMBJ20A-HRA) specify 18.6A and 19.4A respectively. These minor variations remain within acceptable tolerance for general-purpose TVS applications.

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