3KP85-B Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The 3KP85-B is a unidirectional Zener-type transient voltage suppressor manufactured by Littelfuse, designed for general-purpose overvoltage protection applications. This through-hole axial component operates across a temperature range of -55°C to 175°C and is RoHS3 compliant. The part is currently listed as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support, maintenance, and new production requirements.

Substiute Parts

3KP85-B

LittelfuseIn Stock: 9783KP85-B Datasheet

Current PartRFQ

5KP85A-B

Littelfuse Inc.In Stock: 10235KP85A-B Datasheet

DirectRFQ

15KPA85AE3/TR13

Microchip TechnologyIn Stock: 86015KPA85AE3/TR13 Datasheet

MFR RecommendedRFQ

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-TP

Micro Commercial CoIn Stock: 7175KP85A-TP Datasheet

MFR RecommendedRFQ

5KP85AHE3/54

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

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 3KP85-B is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

• Voltage - Reverse Standoff (Typ): 85V (exact match required)
• Voltage - Breakdown (Min): 89.28V to 94.9V (acceptable range)
• Voltage - Clamping (Max) @ Ipp: 137V to 143.85V (acceptable range)
• Current - Peak Pulse (10/1000µs): minimum 21.9A
• Power - Peak Pulse: minimum 3000W
• Operating Temperature: -55°C ~ 175°C (exact match required)
• Type: Zener (exact match required)
• Unidirectional Channels: 1 (exact match required)

Mechanical Compatibility Criteria:

• Mounting Type: Through Hole (exact match required)
• Package / Case: P600 or R-6 Axial (compatible footprints)

Compliance Criteria:

• RoHS Status: ROHS3 Compliant (required)
• Product Status: Active preferred for new designs; obsolete acceptable for legacy support

Substitute parts must satisfy all electrical criteria within the specified ranges and maintain mechanical compatibility. Parts with higher power ratings or peak pulse currents are acceptable as they provide equivalent or superior protection capability.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitutes (P600 Package, Direct Footprint Compatibility):

1. 5KP85A-B (Littelfuse Inc.) — Active product status with identical manufacturer lineage. Provides 5kW peak pulse power versus 3kW of the original, with 37.2A peak pulse current. P600 axial package maintains direct PCB compatibility. ROHS3 compliant. Recommended for designs requiring continued Littelfuse component qualification.

2. 5KP85A-E3/54 (Vishay General Semiconductor - Diodes Division) — Active TransZorb® series product with 5kW peak pulse power and 36.5A peak pulse current. P600 axial package. ROHS3 compliant with REACH unaffected status. Highest inventory availability (8300 pcs). Suitable for high-volume production requirements.

3. 5KP85AHE3/54 (Vishay General Semiconductor - Diodes Division) — Active product with automotive-grade qualification (AEC-Q101). Identical electrical specifications to 5KP85A-E3/54 with P600 axial package. ROHS3 compliant. Recommended for automotive or mission-critical applications requiring enhanced reliability documentation.

Secondary Substitute (Higher Power Rating):

4. 15KPA85AE3/TR13 (Microchip Technology) — Active product with 15kW peak pulse power and 109.7A peak pulse current. Provides maximum overvoltage protection margin. P600 axial package. ROHS3 compliant with REACH unaffected status. Suitable for high-energy transient environments or applications with stringent protection requirements.

Alternative Package Substitutes (R-6 Axial):

5. 3KP85A-TP (Micro Commercial Co) — Active product with identical 3kW power rating and 21.9A peak pulse current matching the original 3KP85-B. R-6 axial package requires PCB layout verification for footprint compatibility. Recommended only when P600 package space is unavailable.

6. 5KP85A-TP (Micro Commercial Co) — Active product with 5kW peak pulse power. R-6 axial package. Requires PCB layout verification. Peak pulse current specification not provided; verify against application requirements before selection.

Selection Priority:

• For direct replacement with enhanced capability: 5KP85A-B or 5KP85A-E3/54
• For automotive applications: 5KP85AHE3/54
• For maximum protection margin: 15KPA85AE3/TR13
• For package-constrained designs: 3KP85A-TP or 5KP85A-TP (verify R-6 compatibility)

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with a higher power rating than the original 3KP85-B?

A: Yes. Substitute parts with higher peak pulse power ratings (5kW or 15kW versus 3kW) provide equivalent or superior transient voltage suppression. Higher power ratings indicate greater energy dissipation capability and do not negatively impact circuit performance. The 85V reverse standoff voltage and clamping characteristics remain the primary functional parameters.

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

A: Both are through-hole axial packages for TVS diodes. P600 and R-6 have different physical dimensions and lead spacing. Direct PCB footprint compatibility cannot be assumed between these packages. Verify your PCB layout specifications before selecting a substitute with an alternative package designation.

Q: Are all listed substitutes compatible with my existing PCB design?

A: Substitutes with P600 axial packages (5KP85A-B, 5KP85A-E3/54, 5KP85AHE3/54, 15KPA85AE3/TR13) are directly compatible with PCBs designed for the 3KP85-B. Substitutes with R-6 axial packages (3KP85A-TP, 5KP85A-TP) require PCB layout verification. Consult your PCB design documentation or contact your PCB manufacturer to confirm footprint compatibility.

Q: Why is the 3KP85-B listed as obsolete?

A: The 3KP85-B is no longer manufactured by Littelfuse. All listed substitute parts are active products from current manufacturers, ensuring long-term availability and supply chain stability for new designs and ongoing production support.

Q: What does ROHS3 compliance mean for my application?

A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements, restricting lead, cadmium, mercury, and other hazardous materials. All listed substitutes are ROHS3 compliant, ensuring regulatory compliance for commercial and industrial applications.

Q: Can I use the 15KPA85AE3/TR13 in place of the 3KP85-B without circuit modifications?

A: Yes. The 15KPA85AE3/TR13 maintains the same 85V reverse standoff voltage and operates within the same temperature range. The higher 15kW power rating and 109.7A peak pulse current provide enhanced protection without requiring circuit modifications. Verify P600 package compatibility with your PCB layout.

Q: What is the significance of the Tape & Reel (TR) packaging for the 15KPA85AE3/TR13?

A: Tape & Reel packaging is standard for high-volume automated assembly processes. This packaging format does not affect electrical performance or through-hole mounting compatibility. It indicates the part is optimized for production environments using pick-and-place equipment.

Q: Are Vishay TransZorb® parts equivalent to standard Littelfuse TVS diodes?

A: Yes. TransZorb® is Vishay's product line designation for TVS diodes. The 5KP85A-E3/54 and 5KP85AHE3/54 meet identical electrical specifications (85V standoff, 137V clamping, 5kW power) as equivalent Littelfuse products. TransZorb® parts are functionally interchangeable based on electrical parameters.

Q: What does AEC-Q101 qualification mean for the 5KP85AHE3/54?

A: AEC-Q101 is an automotive electronics qualification standard. The 5KP85AHE3/54 has undergone enhanced reliability testing and documentation required for automotive applications. This qualification is beneficial for mission-critical or automotive designs but is not required for general industrial applications.