3KP8.5A Equivalent & Substitute Parts

Part Overview

The 3KP8.5A is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose transient voltage protection in through-hole applications. This component features an 8.5V reverse standoff voltage, 14.4V maximum clamping voltage, and 3000W peak pulse power rating in a P600 axial package. The part is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Substiute Parts

3KP8.5A

Littelfuse Inc.In Stock: 12273KP8.5A Datasheet

Current PartRFQ

5KP8.5A

LittelfuseIn Stock: 3001105KP8.5A Datasheet

DirectRFQ

3KP8.5A-TP

Micro Commercial CoIn Stock: 11643KP8.5A-TP Datasheet

DirectRFQ

5KP8.5A-E3/54

Vishay General Semiconductor - Diodes DivisionIn Stock: 19125KP8.5A-E3/54 Datasheet

MFR RecommendedRFQ

5KP8.5A-E3/73

Vishay General Semiconductor - Diodes DivisionIn Stock: 7415KP8.5A-E3/73 Datasheet

MFR RecommendedRFQ

5KP8.5AHE3/54

Vishay General Semiconductor - Diodes DivisionIn Stock: 7275KP8.5AHE3/54 Datasheet

MFR RecommendedRFQ

5KP8.5AHE3/73

Vishay General Semiconductor - Diodes DivisionIn Stock: 10435KP8.5AHE3/73 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 3KP8.5A is determined by the following critical parameters that must remain constant across all equivalent parts:

• Voltage - Reverse Standoff (Typ): 8.5V
• Voltage - Breakdown (Min): 9.44V
• Voltage - Clamping (Max) @ Ipp: 14.4V
• Unidirectional Channels: 1
• Type: Zener
• Operating Temperature: -55°C ~ 175°C (TJ)
• Mounting Type: Through Hole
• RoHS Status: ROHS3 Compliant

Substitute parts are grouped into two categories based on power rating and peak pulse current capability:

Category A - Direct Electrical Equivalents (3000W Rating): Parts maintaining identical power dissipation and peak pulse current specifications as the original 3KP8.5A.

Category B - Enhanced Performance Substitutes (5000W Rating): Parts with identical voltage parameters but increased power handling capability, suitable for applications requiring higher transient energy absorption.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications):

The 3KP8.5A-TP from Micro Commercial Co provides electrical and thermal equivalence with matching 3000W power rating and 208.3A peak pulse current. This part maintains the same voltage parameters and operating temperature range. However, the package designation differs (R-6 versus P600), requiring mechanical verification for board layout compatibility.

For Enhanced Performance Applications:

The 5KP8.5A series from Littelfuse offers increased power handling (5000W) and peak pulse current (354.2A) while maintaining identical voltage specifications. This part is actively manufactured and provides superior transient energy absorption capability. The 5KP8.5A is available in the standard P600 package matching the original design.

For Manufacturer-Recommended Substitutes:

Vishay General Semiconductor TransZorb® series parts (5KP8.5A-E3/54, 5KP8.5A-E3/73, 5KP8.5AHE3/54, 5KP8.5AHE3/73) are actively produced alternatives with 5000W power rating and 347A peak pulse current. All maintain identical voltage parameters and operating temperature specifications. The automotive-grade variants (5KP8.5AHE3/54 and 5KP8.5AHE3/73) carry AEC-Q101 qualification for applications requiring automotive-level reliability.

Compliance Considerations:

All recommended substitutes maintain ROHS3 compliance. Selection between standard and automotive-grade variants depends on application requirements and qualification standards.

Frequently Asked Questions (FAQ)

Q: Can the 5KP8.5A series be used as a direct replacement for the 3KP8.5A?

A: Yes, electrically. The 5KP8.5A maintains identical voltage parameters (8.5V standoff, 14.4V clamping) and operating temperature range. The primary difference is increased power dissipation capability (5000W versus 3000W), which provides enhanced protection without affecting circuit operation. Package compatibility (P600 axial) is identical.

Q: What is the significance of the different peak pulse current ratings?

A: Peak pulse current directly correlates to the component's ability to absorb transient energy. The 3KP8.5A handles 208.3A, while 5KP series variants handle 347-354.2A. Higher current capability allows the device to suppress larger transient events without exceeding voltage clamping limits. Selection depends on the maximum transient current expected in the application.

Q: Are the Vishay TransZorb® parts interchangeable with Littelfuse parts?

A: Yes, for voltage and thermal specifications. All Vishay 5KP8.5A variants maintain the same 8.5V standoff voltage, 14.4V clamping voltage, and -55°C to 175°C operating range. Differences exist in peak pulse current (347A for Vishay versus 354.2A for Littelfuse 5KP8.5A) and packaging options, but these do not prevent functional substitution.

Q: What is the difference between standard and automotive-grade variants?

A: Automotive-grade parts (5KP8.5AHE3/54 and 5KP8.5AHE3/73) carry AEC-Q101 qualification, indicating compliance with automotive reliability and testing standards. These variants are suitable for automotive and mission-critical applications requiring enhanced qualification documentation. Standard variants are appropriate for general industrial and consumer applications.

Q: Does the R-6 package of the 3KP8.5A-TP differ functionally from the P600 package?

A: No functional difference exists in electrical performance. Both are axial through-hole packages for the same component type. The R-6 designation indicates a different physical form factor. Board layout and mechanical mounting must be verified before substitution to ensure compatibility with existing PCB designs.

Q: Why is the original 3KP8.5A listed as obsolete?

A: Obsolescence typically reflects manufacturer discontinuation decisions based on market demand and product line consolidation. Active alternatives with equivalent or superior specifications are available from multiple manufacturers, making the original part unnecessary for new designs or ongoing procurement.