3KP85A-B Equivalent & Substitute Parts

Part Overview

The 3KP85A-B is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. This component features an 85V reverse standoff voltage with a 137V maximum clamping voltage and 21.9A peak pulse current capability in a through-hole P600 axial package. The product is currently obsolete, making equivalent and substitute parts necessary for ongoing design support and component procurement.

Substiute Parts

3KP85A-B

Littelfuse Inc.In Stock: 9423KP85A-B Datasheet

Current PartRFQ

5KP85A-B

Littelfuse Inc.In Stock: 10235KP85A-B Datasheet

DirectRFQ

3KP85A-TP

Micro Commercial CoIn Stock: 10163KP85A-TP Datasheet

MFR RecommendedRFQ

5KP85A-E3/54

Vishay General Semiconductor - Diodes DivisionIn Stock: 83255KP85A-E3/54 Datasheet

MFR RecommendedRFQ

5KP85A-E3/73

Vishay General Semiconductor - Diodes DivisionIn Stock: 9585KP85A-E3/73 Datasheet

MFR RecommendedRFQ

5KP85AHE3/54

Vishay General Semiconductor - Diodes DivisionIn Stock: 10515KP85AHE3/54 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the 3KP85A-B is determined by the following critical electrical and mechanical parameters:

• Voltage Rating: Reverse standoff voltage of 85V, breakdown minimum of 94.4V, and clamping voltage maximum of 137V must be maintained
• Current Capability: Peak pulse current of 21.9A minimum
• Power Dissipation: Peak pulse power of 3000W minimum
• Package Compatibility: Through-hole axial package (P600 or equivalent R-6)
• Temperature Range: Operating range of -55°C to 175°C
• Compliance: ROHS3 compliance required

Substitute parts are grouped into two categories:

Category 1: Direct Electrical Equivalents (Same Power Rating) Parts maintaining the 3000W power dissipation and 21.9A current specification with identical voltage parameters.

Category 2: Enhanced Performance Substitutes (Higher Power Rating) Parts with 5000W power dissipation and higher peak pulse current (36.5A to 37.2A) that exceed the original specification while maintaining all voltage parameters and compatibility.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Same Power Rating):

The 3KP85A-TP from Micro Commercial Co is the primary direct equivalent, maintaining identical electrical specifications (21.9A peak pulse current, 3000W power dissipation) and operating temperature range. This part is currently active and available. Package consideration: the 3KP85A-TP uses an R-6 axial package instead of P600; verify mechanical fit in the application before selection.

For Enhanced Performance Applications:

The 5KP series substitutes (5KP85A-B, 5KP85A-E3/54, 5KP85A-E3/73, and 5KP85AHE3/54) provide higher peak pulse current (36.5A to 37.2A) and increased power dissipation (5000W), offering improved transient protection margin. All maintain the critical voltage parameters (85V standoff, 137V clamping) and through-hole mounting compatibility. These parts are all currently active with established supply availability.

For Automotive Applications:

The 5KP85AHE3/54 is qualified to AEC-Q101 automotive standards and carries Automotive grade designation, making it suitable for automotive and harsh-environment applications requiring enhanced reliability qualification.

Compliance Considerations:

All recommended substitutes maintain ROHS3 compliance. The 5KP series parts from Vishay and Littelfuse carry REACH Unaffected status, providing additional regulatory assurance for international applications.

Frequently Asked Questions (FAQ)

Q: Can the 5KP85A series directly replace the 3KP85A-B?

A: Yes, electrically. The 5KP series maintains all critical voltage parameters (85V standoff, 94.4V breakdown minimum, 137V clamping maximum) and operating temperature range. The higher current and power ratings (37.2A, 5000W versus 21.9A, 3000W) provide enhanced protection capability. Verify mechanical fit in your application, as package dimensions may vary.

Q: What is the difference between P600 and R-6 packages?

A: Both are through-hole axial packages for TVS diodes. P600 and R-6 are different mechanical package designations. The 3KP85A-TP uses R-6 packaging while the original 3KP85A-B uses P600. Confirm your PCB footprint compatibility before substitution.

Q: Why are there multiple 5KP85A variants (E3/54, E3/73, HE3/54)?

A: These designations represent different manufacturing codes and packaging options from Vishay. All three (5KP85A-E3/54, 5KP85A-E3/73, 5KP85AHE3/54) maintain identical electrical specifications and are functionally interchangeable for the 3KP85A-B application. The HE3/54 variant includes automotive qualification (AEC-Q101).

Q: Is the 3KP85A-TP a better choice than the 5KP series for my application?

A: The 3KP85A-TP is the direct electrical equivalent with matching power dissipation (3000W). Select this if your circuit design is validated for 3000W peak pulse power. Choose the 5KP series if your application benefits from higher transient current handling or if you require additional protection margin.

Q: Are all substitutes ROHS3 compliant?

A: The 3KP85A-TP compliance status is not specified in available data. All 5KP series substitutes (5KP85A-B, 5KP85A-E3/54, 5KP85A-E3/73, 5KP85AHE3/54) are confirmed ROHS3 compliant. Verify compliance requirements with your procurement specifications.

Q: Which substitute has the best availability?

A: The 5KP85A-E3/54 from Vishay shows the highest inventory (8300 pcs), followed by 5KP85AHE3/54 (1012 pcs) and 5KP85A-E3/73 (947 pcs). The 3KP85A-TP has 940 pcs available. Littelfuse 5KP85A-B has 1002 pcs in stock.