1SMB85AT3 Equivalent & Substitute Parts

Part Overview

The 1SMB85AT3 is a transient voltage suppressor (TVS) diode manufactured by onsemi, designed for general-purpose overvoltage protection in surface mount applications. This unidirectional Zener diode features an 85V reverse standoff voltage with a 137V maximum clamping voltage and 4.4A peak pulse current capability in the DO-214AA (SMB) package. The part is currently obsolete, making equivalent and substitute parts necessary for ongoing design support and production requirements.

Key Parameters

Parameter	Value
Manufacturer Part Number	1SMB85AT3
Manufacturer	onsemi
Category	Transient Voltage Suppressors (TVS)
Type	Zener
Unidirectional Channels	1
Voltage - Reverse Standoff (Typ)	85V
Voltage - Breakdown (Min)	94.4V
Voltage - Clamping (Max) @ Ipp	137V
Current - Peak Pulse (10/1000µs)	4.4A
Power - Peak Pulse	600W
Package / Case	DO-214AA, SMB
Mounting Type	Surface Mount
Operating Temperature	-65°C ~ 150°C (TJ)
Product Status	Obsolete
RoHS Status	RoHS non-compliant

Substitute Part Grouping Explanation

Substitution for the 1SMB85AT3 is determined by strict electrical and mechanical parameter matching:

Primary Substitution Criteria:

Voltage - Reverse Standoff (Typ): 85V
Voltage - Clamping (Max) @ Ipp: 137V
Current - Peak Pulse (10/1000µs): 4.4A (±0.2A tolerance acceptable)
Package / Case: DO-214AA (SMB)
Mounting Type: Surface Mount
Type: Zener, Unidirectional

Direct Equivalents maintain all electrical parameters within specification and are manufactured by different suppliers with active product status and RoHS3 compliance.

Similar Parts share the same voltage and clamping specifications but may have minor variations in peak pulse current (within 0.3A) or operating temperature range. These parts are functionally compatible for the same application requirements.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (Typ)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Package / Case	Operating Temperature	Product Status	RoHS Status
1SMB85AT3	onsemi	85V	137V	4.4A	DO-214AA, SMB	-65°C ~ 150°C	Obsolete	RoHS non-compliant
SMBJ85A	Meritek	85V	137V	4.38A	DO-214AA (SMB)	-55°C ~ 150°C	Active	ROHS3 Compliant
SMBJ85A-13-F	Diodes Incorporated	85V	137V	4.4A	DO-214AA, SMB	-55°C ~ 150°C	Active	ROHS3 Compliant
SMBJ85A-HR	Littelfuse Inc.	85V	137V	4.4A	DO-214AA, SMB	-65°C ~ 150°C	Active	ROHS3 Compliant
SMBJ85A-HRA	Littelfuse Inc.	85V	137V	4.4A	DO-214AA, SMB	-65°C ~ 150°C	Active	ROHS3 Compliant
SMBJ85A-M3/52	Vishay General Semiconductor - Diodes Division	85V	137V	4.4A	DO-214AA, SMB	-55°C ~ 150°C	Active	ROHS3 Compliant
SMBJ85A-M3/5B	Vishay General Semiconductor - Diodes Division	85V	137V	4.4A	DO-214AA, SMB	-55°C ~ 150°C	Active	ROHS3 Compliant
SMBJ85AE3/TR13	Microchip Technology	85V	137V	4.4A	DO-214AA, SMB	-65°C ~ 150°C	Active	ROHS3 Compliant
SMBJ78CA-TP	Micro Commercial Co	78V	126V	4.7A	DO-214AA, SMB	-55°C ~ 175°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Preferred): Select SMBJ85A-13-F (Diodes Incorporated), SMBJ85A-HR (Littelfuse Inc.), SMBJ85A-HRA (Littelfuse Inc.), SMBJ85A-M3/52 (Vishay), SMBJ85A-M3/5B (Vishay), or SMBJ85AE3/TR13 (Microchip Technology). All maintain identical electrical specifications (85V standoff, 137V clamping, 4.4A peak pulse) and are available in active production status with ROHS3 compliance. These parts are pin-compatible and functionally equivalent for direct PCB substitution.

For Extended Temperature Range: SMBJ85A-HR, SMBJ85A-HRA, and SMBJ85AE3/TR13 support the full -65°C to 150°C operating temperature range matching the original 1SMB85AT3 specification.

For Standard Temperature Range Applications: SMBJ85A (Meritek), SMBJ85A-13-F (Diodes Incorporated), SMBJ85A-M3/52 (Vishay), and SMBJ85A-M3/5B (Vishay) operate across -55°C to 150°C, suitable for most commercial and industrial applications.

Compliance Consideration: All recommended substitutes are ROHS3 compliant, addressing the RoHS non-compliance status of the obsolete 1SMB85AT3.

Alternative Voltage Rating: SMBJ78CA-TP (Micro Commercial Co) provides a lower voltage rating (78V standoff, 126V clamping) with higher peak pulse current (4.7A) and extended temperature range (-55°C to 175°C). This part is suitable only for applications where the lower voltage threshold is acceptable.

Frequently Asked Questions (FAQ)

Q: Can SMBJ85A directly replace 1SMB85AT3 in existing designs? A: Yes. SMBJ85A maintains identical electrical specifications (85V standoff, 137V clamping, 4.4A peak pulse) and is packaged in the same DO-214AA (SMB) surface mount case. Pin configuration and footprint are compatible for direct PCB substitution.

Q: What is the difference between SMBJ85A-HR and SMBJ85A-HRA? A: Both parts are manufactured by Littelfuse Inc. and share identical electrical specifications and operating temperature range (-65°C to 150°C). The suffix designations indicate different manufacturing series or packaging variants. Electrical performance and compatibility are equivalent.

Q: Why is SMBJ78CA-TP listed as a similar part rather than a direct substitute? A: SMBJ78CA-TP has a lower reverse standoff voltage (78V vs. 85V) and lower clamping voltage (126V vs. 137V), though peak pulse current is higher (4.7A vs. 4.4A). This part is suitable only for applications with lower voltage protection requirements and should not be used as a direct replacement without circuit re-evaluation.

Q: Are all substitute parts available in tape and reel packaging? A: Yes. All listed substitute parts are available in Tape & Reel (TR) packaging suitable for automated assembly processes.

Q: What compliance certifications apply to the substitute parts? A: All active substitute parts are ROHS3 compliant and REACH unaffected, with ECCN classification EAR99 and HTSUS code 8541.10.0080. Moisture sensitivity level is 1 (Unlimited) for all parts.

Q: Which substitute offers the best thermal performance? A: SMBJ78CA-TP supports the highest operating temperature range (-55°C to 175°C). However, for 85V voltage rating applications, SMBJ85A-HR, SMBJ85A-HRA, and SMBJ85AE3/TR13 maintain the full -65°C to 150°C range of the original part.

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