Equivalent & Substitute Parts for 3KP51CA-B TVS Diode

Part Overview

The 3KP51CA-B is a Littelfuse transient voltage suppressor (TVS) diode in the 3KP series, designed for general-purpose overvoltage protection applications. This bidirectional zener diode features a 51V reverse standoff voltage with an 82.4V maximum clamping voltage and 36.4A peak pulse current capability in a through-hole P600 axial package. The part is currently obsolete, necessitating identification of functionally equivalent alternatives from active product lines to maintain circuit protection performance and design continuity.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	51	V
Voltage - Breakdown (Min)	56.7	V
Voltage - Clamping (Max) @ Ipp	82.4	V
Current - Peak Pulse (10/1000µs)	36.4	A
Power - Peak Pulse	3000	W
Operating Temperature Range	-55 to 175	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	P600, Axial	—
Type	Zener	—
Bidirectional Channels	1	—

Substitute Part Grouping Explanation

Substitution of the 3KP51CA-B is determined by strict equivalence across the following critical parameters:

Voltage - Reverse Standoff (Typ): 51V
Voltage - Clamping (Max) @ Ipp: 82.4V
Voltage - Breakdown (Min): 56.7V
Operating Temperature Range: -55°C to 175°C
Bidirectional Channels: 1
Type: Zener
Mounting Type: Through Hole
Applications: General Purpose

Substitute parts are grouped into two categories based on power rating and current handling:

Category 1: Direct Electrical Equivalents (3kW Power Rating)

3KP51CA-TP (Micro Commercial Co, R-6 package)

Category 2: Higher Power Alternatives (5kW Power Rating)

5KP51CA-B (Littelfuse, P600 package)
5KP51CA-TP (Micro Commercial Co, R-6 package)

All listed substitutes maintain identical voltage specifications and temperature operating range. Differences in peak pulse current and power dissipation reflect the series designation (3KP vs. 5KP) and do not affect voltage-based protection thresholds.

Parameter Comparison

Parameter	3KP51CA-B (Main)	3KP51CA-TP	5KP51CA-B	5KP51CA-TP
Manufacturer	Littelfuse Inc.	Micro Commercial Co	Littelfuse	Micro Commercial Co
Product Status	Obsolete	Active	Active	Active
Voltage - Reverse Standoff (Typ)	51V	51V	51V	51V
Voltage - Breakdown (Min)	56.7V	56.7V	56.7V	56.7V
Voltage - Clamping (Max) @ Ipp	82.4V	82.4V	82.4V	82.4V
Current - Peak Pulse (10/1000µs)	36.4A	36.4A	61.9A	—
Power - Peak Pulse	3000W	3000W	5000W	5000W
Operating Temperature	-55 to 175°C	-55 to 175°C	-55 to 175°C	-55 to 175°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	P600, Axial	R-6, Axial	P600, Axial	R-6, Axial
RoHS Status	ROHS3 Compliant	—	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

For Direct Replacement (Identical Electrical and Power Specifications): Select 3KP51CA-TP from Micro Commercial Co when package footprint compatibility with R-6 axial configuration is acceptable. This part maintains active product status and ROHS3 compliance.

For Enhanced Transient Protection (Higher Power Dissipation): Select 5KP51CA-B (Littelfuse, P600 package) or 5KP51CA-TP (Micro Commercial Co, R-6 package) when circuit design permits higher peak pulse current handling (61.9A vs. 36.4A) and increased power dissipation (5kW vs. 3kW). Both maintain identical voltage protection thresholds and active product status.

Package Consideration: The P600 package (3KP51CA-B and 5KP51CA-B) and R-6 package (3KP51CA-TP and 5KP51CA-TP) are both axial through-hole configurations. PCB layout and lead spacing requirements determine package selection.

Frequently Asked Questions (FAQ)

Q: Can 3KP51CA-TP be used as a direct replacement for 3KP51CA-B? A: Yes. Both parts share identical voltage specifications (51V standoff, 82.4V clamping), current ratings (36.4A peak pulse), and power dissipation (3kW). The primary difference is the package type: P600 versus R-6 axial. Verify PCB footprint compatibility before substitution.

Q: What is the difference between 3KP and 5KP series TVS diodes? A: The series designation indicates power rating and peak pulse current capability. The 3KP series handles 3kW peak pulse power at 36.4A, while the 5KP series handles 5kW peak pulse power at 61.9A. Both maintain identical voltage protection thresholds when rated for the same voltage class (51V in this case).

Q: Can I use a 5KP51CA part instead of 3KP51CA-B? A: Yes. The 5KP51CA-B and 5KP51CA-TP provide higher transient energy absorption capability (5kW vs. 3kW) while maintaining the same voltage protection characteristics. This substitution is suitable when circuit transient conditions may exceed the 3kW rating or when design margin improvement is desired.

Q: Are all substitute parts RoHS3 compliant? A: The 3KP51CA-TP, 5KP51CA-B, and 5KP51CA-TP are all ROHS3 compliant. Compliance documentation should be verified with the specific supplier for the selected part.

Q: What is the significance of the P600 and R-6 package designations? A: Both are through-hole axial packages for TVS diodes. P600 and R-6 refer to different physical lead configurations and spacing. Selection depends on PCB design requirements and available footprint space. Consult package datasheets for precise dimensional specifications.

Q: Why is the 3KP51CA-B listed as obsolete? A: Littelfuse has transitioned this part to obsolete status. Active alternatives from both Littelfuse (5KP series) and Micro Commercial Co (3KP and 5KP series) are available to maintain design continuity and supply chain reliability.

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