3KP18A-B Equivalent & Substitute Parts

Part Overview

The 3KP18A-B is a unidirectional Zener transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. This component features an 18V reverse standoff voltage with a 29.2V maximum clamping voltage and 102.7A peak pulse current capability in a through-hole P600 axial package. The part is currently classified as obsolete, necessitating identification of functionally equivalent alternatives for new designs and ongoing maintenance applications.

Substiute Parts

3KP18A-B

Littelfuse Inc.In Stock: 9953KP18A-B Datasheet

Current PartRFQ

5KP18A-B

Littelfuse Inc.In Stock: 7205KP18A-B Datasheet

DirectRFQ

3KP18A-TP

Micro Commercial CoIn Stock: 10163KP18A-TP Datasheet

MFR RecommendedRFQ

5KP18A-TP

Micro Commercial CoIn Stock: 20485KP18A-TP Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 3KP18A-B is determined by the following critical parameters:

• Voltage Rating Match: Reverse standoff voltage of 18V, breakdown minimum of 20V, and clamping voltage of 29.2V
• Current Handling: Peak pulse current capability of 102.7A or greater
• Power Dissipation: Peak pulse power rating of 3000W or greater
• Package Compatibility: Through-hole axial configuration (P600 or equivalent R-6 package)
• Temperature Range: Operating range of -55°C to 175°C
• Device Type: Unidirectional Zener TVS diode

Substitute parts are grouped into two categories based on these parameters: direct equivalents with identical electrical specifications and higher-rated alternatives with enhanced current and power handling capabilities.

Parameter Comparison

Engineering Selection Recommendations

Direct Electrical Equivalent (Same Power Rating): The 3KP18A-TP manufactured by Micro Commercial Co provides identical electrical specifications with 102.7A peak pulse current and 3000W power dissipation. This part maintains active product status and ROHS3 compliance. Package transition from P600 to R-6 axial configuration requires mechanical verification for board layout compatibility.

Enhanced Performance Alternative (Higher Power Rating): The 5KP18A-B from Littelfuse Inc. and 5KP18A-TP from Micro Commercial Co both offer increased current handling (174.7A) and power dissipation (5000W) while maintaining identical voltage specifications. These parts are suitable for applications requiring additional transient energy absorption margin. The 5KP18A-B maintains the original P600 package, while 5KP18A-TP uses the R-6 package.

Compliance Considerations: All recommended substitutes maintain ROHS3 compliance and the required operating temperature range. The 5KP18A-B and 5KP18A-TP include REACH Unaffected status documentation.

Frequently Asked Questions (FAQ)

Q: Can the 5KP18A-B replace the 3KP18A-B in all applications? A: The 5KP18A-B maintains identical voltage specifications (18V standoff, 29.2V clamping) and operating temperature range. The increased current rating (174.7A vs 102.7A) and power dissipation (5000W vs 3000W) provide additional protection margin. Substitution is valid for all applications where the original 3KP18A-B was specified, with the benefit of enhanced transient suppression capability.

Q: What is the difference between P600 and R-6 packages? A: Both are through-hole axial packages for TVS diodes. P600 is the original Littelfuse package designation, while R-6 is the equivalent package used by Micro Commercial Co. Physical dimensions and lead spacing are compatible for standard through-hole PCB layouts. Verify specific board footprint requirements before substitution.

Q: Are MCC parts (3KP18A-TP, 5KP18A-TP) fully compatible with Littelfuse originals? A: MCC parts provide electrical equivalence with identical voltage and temperature specifications. Both manufacturers' parts are ROHS3 compliant and suitable for the same applications. Package designation differs (R-6 vs P600), requiring mechanical compatibility verification. Active product status for MCC parts ensures long-term availability.

Q: Why is the 3KP18A-B marked as obsolete? A: Obsolete status indicates the part is no longer manufactured by Littelfuse Inc. The 5KP18A-B and MCC alternatives (3KP18A-TP, 5KP18A-TP) provide equivalent or enhanced functionality with active product status and confirmed availability.

Q: Can I use a substitute part with higher power rating in a space-constrained design? A: The 5KP series parts maintain the same through-hole axial package dimensions as the 3KP series. Higher power rating does not increase physical size. Substitution is mechanically feasible without design modification.