SZ1SMB85AT3G Equivalent & Substitute Parts

Part Overview

The SZ1SMB85AT3G is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Littelfuse Inc., designed for surface mount applications in the DO-214AA (SMB) package. This component operates with an 85V reverse standoff voltage and provides 137V maximum clamping voltage at peak pulse current, delivering 600W peak pulse power dissipation. The device is qualified to AEC-Q101 automotive standards and maintains active product status. Substitute parts are identified to address inventory availability, extended temperature range requirements, or specific application needs while maintaining electrical and mechanical compatibility within defined parameter tolerances.

Substiute Parts

SZ1SMB85AT3G

Littelfuse Inc.In Stock: 3706SZ1SMB85AT3G Datasheet

Current PartRFQ

SMBJE78AH

Eaton - Electronics DivisionIn Stock: 3668SMBJE78AH Datasheet

MFR RecommendedRFQ

SMBJE85AH

Eaton - Electronics DivisionIn Stock: 6667SMBJE85AH Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SZ1SMB85AT3G are selected based on strict electrical and mechanical parameter alignment. The primary substitution criteria are:

Electrical Parameters:

• Voltage - Reverse Standoff (Typ): 85V nominal operation point
• Voltage - Clamping (Max) @ Ipp: 137V maximum transient suppression level
• Current - Peak Pulse (10/1000µs): 4.4A pulse handling capacity
• Power - Peak Pulse: 600W dissipation capability

Mechanical Parameters:

• Package / Case: DO-214AA (SMB) surface mount configuration
• Mounting Type: Surface Mount
• Unidirectional Channels: 1

Compliance Parameters:

• Grade: Automotive
• Qualification: AEC-Q101
• RoHS Status: ROHS3 Compliant
• Moisture Sensitivity Level: 1 (Unlimited)

Substitute parts must maintain identical or equivalent electrical performance within the specified voltage and current ranges, use the same surface mount package, and retain automotive-grade qualification. The SMBJE85AH provides direct electrical equivalence with identical clamping voltage and peak pulse current. The SMBJE78AH offers lower voltage standoff (78V) with slightly higher peak pulse current (4.8A), suitable for applications requiring lower voltage thresholds while maintaining equivalent power dissipation.

Parameter Comparison

Engineering Selection Recommendations

SMBJE85AH (Direct Equivalent): The SMBJE85AH from Eaton - Electronics Division provides direct electrical equivalence to the SZ1SMB85AT3G. Both devices maintain identical reverse standoff voltage (85V), breakdown voltage (94.4V minimum), clamping voltage (137V maximum), and peak pulse current (4.4A). Both are qualified to AEC-Q101 automotive standards, ROHS3 compliant, and packaged in DO-214AA (SMB) surface mount configuration. The SMBJE85AH is suitable for direct replacement in applications where the SZ1SMB85AT3G is specified. Inventory availability is higher (6616 pcs vs. 3600 pcs). Operating temperature range is -55 to 150°C, which covers the upper operating point of the main part but does not extend to the lower -65°C minimum of the SZ1SMB85AT3G.

SMBJE78AH (Lower Voltage Alternative): The SMBJE78AH from Eaton - Electronics Division operates at a lower reverse standoff voltage (78V) with correspondingly lower breakdown voltage (86.7V minimum) and clamping voltage (126V maximum). Peak pulse current is slightly higher at 4.8A. This substitute is applicable only in applications where the lower voltage thresholds are acceptable and do not conflict with circuit protection requirements. Both devices share identical power dissipation (600W), AEC-Q101 qualification, ROHS3 compliance, and DO-214AA (SMB) packaging. Operating temperature range is -55 to 150°C. Inventory availability is comparable (3576 pcs).

Temperature Range Consideration: The SZ1SMB85AT3G specifies an operating temperature range of -65 to 150°C. Both Eaton substitutes limit the lower operating temperature to -55°C. Selection of substitute parts should account for this 10°C difference in minimum operating temperature if the application requires operation below -55°C.

Frequently Asked Questions (FAQ)

Q: Can SMBJE85AH be used as a direct replacement for SZ1SMB85AT3G?

A: Yes. The SMBJE85AH provides identical electrical parameters: 85V reverse standoff voltage, 137V clamping voltage, and 4.4A peak pulse current. Both devices are AEC-Q101 qualified, ROHS3 compliant, and packaged in DO-214AA (SMB). The primary difference is the operating temperature minimum: SZ1SMB85AT3G operates to -65°C while SMBJE85AH operates to -55°C. Direct replacement is valid for applications not requiring operation below -55°C.

Q: When should SMBJE78AH be selected instead of the main part?

A: SMBJE78AH is selected only when the application circuit design permits lower voltage thresholds. The 78V reverse standoff voltage and 126V clamping voltage are 7V lower than the SZ1SMB85AT3G. This substitute is not interchangeable for circuits designed around the 85V protection level. Verify circuit requirements before substitution.

Q: Are all substitute parts in the same package?

A: Yes. The SZ1SMB85AT3G, SMBJE78AH, and SMBJE85AH all use the DO-214AA (SMB) surface mount package. Physical footprint and mounting requirements are identical, allowing direct PCB placement compatibility.

Q: What is the impact of the operating temperature range difference?

A: The SZ1SMB85AT3G operates from -65°C to 150°C, while both Eaton substitutes operate from -55°C to 150°C. If the application requires operation below -55°C, the SZ1SMB85AT3G or equivalent parts with extended low-temperature ratings must be used. For applications within -55°C to 150°C, the temperature range difference is not a limiting factor.

Q: Do all parts meet automotive qualification requirements?

A: Yes. The SZ1SMB85AT3G, SMBJE78AH, and SMBJE85AH are all qualified to AEC-Q101 automotive standards and are ROHS3 compliant. All three parts are suitable for automotive applications requiring transient voltage suppression.

Q: What is the capacitance specification for substitute parts?

A: Capacitance data is provided only for the SZ1SMB85AT3G (220pF @ 1MHz). Capacitance specifications are not provided in the input data for SMBJE78AH or SMBJE85AH. If capacitance is a critical parameter for the application, consult the manufacturer datasheets for Eaton parts or contact the supplier for complete specifications.

Q: Are there inventory differences between the parts?

A: Yes. Current inventory levels are: SZ1SMB85AT3G (3600 pcs), SMBJE78AH (3576 pcs), and SMBJE85AH (6616 pcs). The SMBJE85AH has significantly higher inventory availability, which may be relevant for high-volume procurement or extended lead time mitigation.