3KP18A Equivalent & Substitute Parts

Part Overview

The 3KP18A is a unidirectional 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 at 3000W peak pulse power. The 3KP18A is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain identical electrical characteristics while offering active product status and improved availability.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	18	V
Voltage - Breakdown (Min)	20	V
Voltage - Clamping (Max) @ Ipp	29.2	V
Current - Peak Pulse (10/1000µs)	102.7	A
Power - Peak Pulse	3000	W
Operating Temperature Range	-55 to 175	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	P600, Axial	—
Type	Zener	—
Unidirectional Channels	1	—

Substitute Part Grouping Explanation

Substitute parts for the 3KP18A are selected based on strict electrical and mechanical compatibility criteria. All substitute candidates must maintain the following core parameters:

Voltage - Reverse Standoff: 18V (typical)
Voltage - Breakdown (Min): 20V
Voltage - Clamping (Max) @ Ipp: 29.2V
Unidirectional configuration (1 channel)
Through-hole mounting
Zener diode type
General-purpose application classification

Substitutes are grouped into two categories:

Category 1: Direct Electrical Equivalents (3KP18A-TP) Parts maintaining identical peak pulse current (102.7A) and power dissipation (3000W) with alternative packaging or supplier options.

Category 2: Enhanced Performance Alternatives (5KP18A, 5KP18A-TP) Parts maintaining all voltage parameters while offering increased peak pulse current (171A) and power dissipation (5000W), suitable for applications requiring higher transient energy absorption.

Parameter Comparison

Parameter	3KP18A (Main)	3KP18A-TP	5KP18A	5KP18A-TP
Manufacturer	Littelfuse Inc.	Micro Commercial Co	Diotec Semiconductor	Micro Commercial Co
Product Status	Obsolete	Active	Active	Active
Voltage - Reverse Standoff (Typ)	18V	18V	18V	18V
Voltage - Breakdown (Min)	20V	20V	20V	20V
Voltage - Clamping (Max) @ Ipp	29.2V	29.2V	29.2V	29.2V
Current - Peak Pulse (10/1000µs)	102.7A	102.7A	171A	—
Power - Peak Pulse	3000W	3000W	5000W	5000W
Operating Temperature Range	-55 to 175°C	-55 to 175°C	-50 to 175°C	-55 to 175°C
Package / Case	P600, Axial	R-6, Axial	P600, Axial	R-6, Axial
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
RoHS Status	ROHS3 Compliant	Not specified	ROHS3 Compliant	ROHS3 Compliant
Inventory Status	1016 Pcs	994 Pcs	4200 Pcs	2026 Pcs

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications): The 3KP18A-TP manufactured by Micro Commercial Co is the primary direct substitute, maintaining 102.7A peak pulse current and 3000W power dissipation. This part carries active product status and ROHS3 compliance. Package variation (R-6 vs. P600) requires PCB layout verification but does not affect electrical performance.

For Enhanced Performance Applications: The 5KP18A (Diotec Semiconductor) and 5KP18A-TP (Micro Commercial Co) provide increased transient energy handling (5000W vs. 3000W) while maintaining all voltage parameters. These parts are suitable for applications experiencing higher transient stress. Both carry active product status and ROHS3 compliance. The 5KP18A offers superior inventory availability (4200 units).

Compliance Considerations: All active substitute parts maintain ROHS3 compliance. The 3KP18A-TP and 5KP18A-TP carry REACH Unaffected status. Temperature range differences (5KP18A operates -50 to 175°C vs. -55 to 175°C for other variants) must be evaluated for applications requiring full -55°C operation.

Frequently Asked Questions (FAQ)

Q: Can 5KP18A parts be used as direct replacements for 3KP18A? A: Yes, electrically. The 5KP18A maintains identical voltage parameters (18V standoff, 29.2V clamping) and unidirectional configuration. The increased current rating (171A vs. 102.7A) and power dissipation (5000W vs. 3000W) provide enhanced protection margin. Package compatibility (P600 axial) matches the original. Applications do not require modification.

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 represent different supplier package designations but maintain identical electrical performance and mounting compatibility. PCB footprint verification is required when switching between package types, though both accommodate standard 0.3-inch lead spacing.

Q: Why is the 3KP18A obsolete? A: Product obsolescence reflects manufacturer discontinuation. Active substitutes (3KP18A-TP, 5KP18A, 5KP18A-TP) provide equivalent or enhanced functionality with ongoing production support and improved supply chain availability.

Q: Are all substitute parts ROHS3 compliant? A: The 3KP18A-TP, 5KP18A, and 5KP18A-TP all carry ROHS3 compliance certification. Compliance status should be verified with the specific supplier for procurement documentation.

Q: What is the minimum operating temperature for each substitute? A: The 3KP18A-TP and 5KP18A-TP operate from -55°C (matching the original 3KP18A). The 5KP18A operates from -50°C. Applications requiring -55°C minimum operation should specify 3KP18A-TP or 5KP18A-TP.

Q: Can I use 5KP18A-TP if peak pulse current specification is not provided? A: The 5KP18A-TP specification lists peak pulse current as unavailable in the provided data. However, the 5KP18A-TP carries 5000W power dissipation rating, indicating capability exceeding the original 3KP18A (3000W). Electrical compatibility is maintained through identical voltage parameters. Supplier datasheet consultation is recommended for complete current specifications.

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