1SMB8.5AT3 Equivalent & Substitute Parts

Part Overview

The 1SMB8.5AT3 is a transient voltage suppressor (TVS) diode manufactured by onsemi, designed for general-purpose overvoltage protection in surface mount applications. This component features an 8.5V reverse standoff voltage with a 14.4V maximum clamping voltage and 41.7A 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 continuity.

Key Parameters

Parameter	Value
Manufacturer Part Number	1SMB8.5AT3
Manufacturer	onsemi
Category	Transient Voltage Suppressors (TVS)
Type	Zener
Voltage - Reverse Standoff (Typ)	8.5V
Voltage - Breakdown (Min)	9.44V
Voltage - Clamping (Max) @ Ipp	14.4V
Current - Peak Pulse (10/1000µs)	41.7A
Power - Peak Pulse	600W
Package / Case	DO-214AA, SMB
Operating Temperature	-65°C ~ 150°C (TJ)
Mounting Type	Surface Mount
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the 1SMB8.5AT3 is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Voltage - Reverse Standoff: 8.5V (±tolerance)
Voltage - Clamping (Max) @ Ipp: 14.4V (±tolerance)
Current - Peak Pulse (10/1000µs): 41.7A (±tolerance)
Package / Case: DO-214AA (SMB)
Mounting Type: Surface Mount
Unidirectional Channels: 1

Substitution Categories:

Direct Equivalents maintain all critical electrical parameters within acceptable tolerance and use identical packaging. These parts are pin-compatible and functionally interchangeable without circuit modification.

Similar Substitutes maintain the core voltage and current specifications but may have minor variations in clamping voltage (±0.1V) or peak pulse current (±2A). These parts are suitable for applications where the tolerance band permits slight parameter deviation.

Alternative Substitutes operate within the same voltage class but may use different package variants (SOD-128) or have different temperature ratings. These require verification of mechanical fit and thermal performance in the target application.

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
1SMB8.5AT3	onsemi	8.5V	14.4V	41.7A	DO-214AA, SMB	-65°C ~ 150°C	Obsolete	RoHS non-compliant
SMBJ8.5A	Taiwan Semiconductor Corporation	8.5V	14.4V	43A	DO-214AA, SMB	-55°C ~ 150°C	Active	ROHS3 Compliant
SMBJ8.5A/54	Vishay General Semiconductor - Diodes Division	8.5V	14.4V	41.7A	DO-214AA, SMB	-55°C ~ 150°C	Active	RoHS non-compliant
P6SMB10A-M3/52	Vishay General Semiconductor - Diodes Division	8.55V	14.5V	41.4A	DO-214AA, SMB	-65°C ~ 150°C	Active	ROHS3 Compliant
P6SMB10A-M3/5B	Vishay General Semiconductor - Diodes Division	8.55V	14.5V	41.4A	DO-214AA, SMB	-65°C ~ 150°C	Active	ROHS3 Compliant
PTVS8V5P1UP,115	NXP USA Inc.	8.5V	14.4V	41.7A	SOD-128	-55°C ~ 150°C	Active	Not specified
SACB8.5	Littelfuse Inc.	8.5V	14V	34A	DO-214AA, SMB	-55°C ~ 150°C	Active	ROHS3 Compliant
SM6T10A-E3/5B	Vishay General Semiconductor - Diodes Division	8.55V	14.5V	41A	DO-214AA, SMB	-65°C ~ 150°C	Active	ROHS3 Compliant
SM6T10A-M3/52	Vishay General Semiconductor - Diodes Division	8.55V	14.5V	41A	DO-214AA, SMB	-65°C ~ 150°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Equivalents (Recommended for Pin-Compatible Replacement):

SMBJ8.5A from Taiwan Semiconductor Corporation and SMBJ8.5A/54 from Vishay General Semiconductor are the closest functional equivalents. Both maintain the 8.5V reverse standoff and 14.4V clamping voltage specifications. SMBJ8.5A is active and RoHS3 compliant, making it suitable for new designs and production environments with RoHS requirements. SMBJ8.5A/54 maintains the original RoHS non-compliant status but offers identical electrical performance.

Active Substitutes with Minor Parameter Tolerance:

P6SMB10A-M3/52 and P6SMB10A-M3/5B from Vishay offer 8.55V reverse standoff and 14.5V clamping voltage, representing a 0.05V and 0.1V deviation respectively. Peak pulse current is 41.4A, within 0.3A of the original specification. Both parts are RoHS3 compliant and support the full -65°C to 150°C temperature range. These parts are suitable where minor parameter variations fall within circuit tolerance bands.

SM6T10A-E3/5B and SM6T10A-M3/52 from Vishay provide similar electrical performance with 8.55V standoff and 14.5V clamping. Peak pulse current is 41A, representing a 1.7A reduction. Both are RoHS3 compliant and support -65°C to 150°C operation. These parts are appropriate for applications where the slightly lower peak pulse current remains within design margins.

Alternative Package Consideration:

PTVS8V5P1UP,115 from NXP USA Inc. maintains identical electrical specifications (8.5V standoff, 14.4V clamping, 41.7A peak pulse) but uses SOD-128 packaging instead of DO-214AA (SMB). This part is suitable only if the PCB layout and mechanical constraints accommodate the different package footprint. Automotive qualification (AEC-Q101) is available for this part.

Lower Current Alternative:

SACB8.5 from Littelfuse Inc. operates at 8.5V standoff and 14V clamping but provides only 34A peak pulse current and 500W peak power. This part is suitable only for applications where the reduced current handling capacity meets design requirements. RoHS3 compliance is available.

Frequently Asked Questions (FAQ)

Q: Can SMBJ8.5A directly replace 1SMB8.5AT3 without circuit modification?

A: Yes. SMBJ8.5A maintains identical reverse standoff voltage (8.5V), clamping voltage (14.4V), and package (DO-214AA/SMB). Peak pulse current is 43A versus 41.7A, representing a 3.1% increase within normal component tolerance. No circuit modification is required.

Q: What is the difference between direct equivalents and similar substitutes?

A: Direct equivalents maintain all critical electrical parameters within ±1% tolerance. Similar substitutes may have clamping voltage variations of ±0.1V or peak pulse current variations of ±2A. Both categories use identical packaging and are pin-compatible, but similar substitutes require verification that the parameter deviation falls within circuit tolerance bands.

Q: Why does PTVS8V5P1UP,115 use a different package?

A: PTVS8V5P1UP,115 uses SOD-128 packaging instead of DO-214AA (SMB). While electrically equivalent, the different package footprint requires PCB layout modification. This part is suitable only if mechanical constraints permit package substitution.

Q: Is RoHS compliance a substitution criterion?

A: RoHS compliance is a regulatory and supply chain consideration, not an electrical substitution criterion. RoHS3-compliant parts (SMBJ8.5A, P6SMB10A series, SM6T10A series, SACB8.5) are preferred for new designs and production environments with RoHS requirements. The original 1SMB8.5AT3 is RoHS non-compliant; SMBJ8.5A/54 maintains this status if legacy compliance is required.

Q: Can SACB8.5 replace 1SMB8.5AT3 in all applications?

A: SACB8.5 is suitable only for applications where the reduced peak pulse current (34A versus 41.7A) and peak power (500W versus 600W) remain within design margins. The 8.5V standoff and 14V clamping voltage are compatible, but the 18% reduction in current handling capacity must be verified against circuit requirements.

Q: What temperature range should I consider for substitution?

A: The original 1SMB8.5AT3 operates from -65°C to 150°C. Most active substitutes operate from -55°C to 150°C, representing a 10°C reduction in minimum operating temperature. For applications requiring -65°C operation, select P6SMB10A-M3/52, P6SMB10A-M3/5B, SM6T10A-E3/5B, or SM6T10A-M3/52.

Q: Are there inventory considerations for substitution?

A: SMBJ8.5A from Taiwan Semiconductor Corporation has 44,300 units in stock, providing substantial availability. SM6T10A from STMicroelectronics has 15,230 units available. Vishay parts (P6SMB10A, SM6T10A variants) have lower inventory levels (685–3,915 units). Littelfuse SACB8.5 has 863 units available. Inventory levels should be verified with suppliers for production planning.

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