3KP45-B Equivalent & Substitute Parts

Part Overview

The 3KP45-B is a unidirectional Zener transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. This component features a 45V reverse standoff voltage, 76.34V maximum clamping voltage, and 3000W peak pulse power rating in a through-hole P600 axial package. The product is currently obsolete, making equivalent and substitute parts necessary for ongoing system support and new designs requiring similar electrical characteristics.

Key Parameters

Parameter	Value
Manufacturer Part Number	3KP45-B
Manufacturer	Littelfuse Inc.
Category	Transient Voltage Suppressors (TVS)
Type	Zener
Voltage - Reverse Standoff (Typ)	45V
Voltage - Breakdown (Min)	47.39V
Voltage - Clamping (Max) @ Ipp	76.34V
Current - Peak Pulse (10/1000µs)	41.3A
Power - Peak Pulse	3000W
Operating Temperature	-55°C ~ 175°C (TJ)
Mounting Type	Through Hole
Package / Case	P600, Axial
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the 3KP45-B is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Voltage - Reverse Standoff: 45V (exact match required)
Voltage - Breakdown (Min): 47.39V to 50.3V (acceptable range)
Voltage - Clamping (Max) @ Ipp: 72.7V to 77.4V (acceptable range)
Current - Peak Pulse (10/1000µs): 41.3A minimum
Power - Peak Pulse: 3000W minimum
Operating Temperature: -55°C ~ 175°C (TJ)
Mounting Type: Through Hole
Package / Case: P600 or R-6 Axial (compatible footprints)
Type: Zener, Unidirectional

Substitute parts are grouped into two categories:

Direct Electrical Equivalents (3kW to 5kW power rating): Parts maintaining the same power class with compatible clamping and breakdown voltages. These include 5KP45A-B, 3KP45A-TP, 5KP45A-E3/54, 5KP45A-E3/73, 5KP45A-TP, 5KP45AHE3/54, and 5KP45AHE3/73.
Higher Power Alternatives (15kW to 30kW power rating): Parts with enhanced current handling and power dissipation for applications requiring greater transient protection margin. These include 15KPA45AE3/TR13 and 30KP45A-TP.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff	Voltage - Breakdown (Min)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Package / Case	Product Status
3KP45-B	Littelfuse Inc.	45V	47.39V	76.34V	41.3A	3000W	P600, Axial	Obsolete
5KP45A-B	Littelfuse Inc.	45V	50V	72.7V	70.2A	5000W	P600, Axial	Active
15KPA45AE3/TR13	Microchip Technology	45V	50.3V	72.8V	207.4A	15000W	P600, Axial	Active
30KP45A-TP	Micro Commercial Co	45V	50.3V	77.4V	—	30000W	R-6, Axial	Active
3KP45A-TP	Micro Commercial Co	45V	50V	72.7V	41.3A	3000W	R-6, Axial	Active
5KP45A-E3/54	Vishay General Semiconductor - Diodes Division	45V	50V	72.7V	68.8A	5000W	P600, Axial	Active
5KP45A-E3/73	Vishay General Semiconductor - Diodes Division	45V	50V	72.7V	68.8A	5000W	P600, Axial	Active
5KP45A-TP	Micro Commercial Co	45V	50V	72.7V	—	5000W	R-6, Axial	Active
5KP45AHE3/54	Vishay General Semiconductor - Diodes Division	45V	50V	72.7V	68.8A	5000W	P600, Axial	Active
5KP45AHE3/73	Vishay General Semiconductor - Diodes Division	45V	50V	72.7V	68.8A	5000W	P600, Axial	Active

Engineering Selection Recommendations

For Direct Replacement (Same Power Class):

The 3KP45A-TP (Micro Commercial Co) is the closest functional equivalent, maintaining identical 45V reverse standoff voltage, 3000W power rating, and 41.3A peak pulse current. This part is active and ROHS3 compliant. The R-6 axial package is mechanically compatible with P600 footprints in standard through-hole applications.

The 5KP45A-B (Littelfuse Inc.), 5KP45A-E3/54, 5KP45A-E3/73, and 5KP45AHE3/54/73 (Vishay) provide enhanced performance with 5000W power rating and higher peak pulse current (68.8A to 70.2A) while maintaining the same 45V standoff voltage and compatible clamping characteristics. All are active products with ROHS3 compliance.

For Enhanced Protection (Higher Power Class):

The 15KPA45AE3/TR13 (Microchip Technology) and 30KP45A-TP (Micro Commercial Co) offer significantly higher power dissipation (15kW and 30kW respectively) for applications requiring greater transient suppression margin. Both maintain 45V standoff voltage and are active, ROHS3-compliant products.

Compliance Considerations:

All substitute parts listed are ROHS3 compliant and operate across the same temperature range (-55°C ~ 175°C). The 5KP45AHE3/54 and 5KP45AHE3/73 variants include AEC-Q101 automotive qualification for applications requiring automotive-grade components.

Frequently Asked Questions (FAQ)

Q: Can I use a 5KP45A series part as a direct replacement for the 3KP45-B?

A: Yes. The 5KP45A series maintains the critical 45V reverse standoff voltage and compatible clamping voltage (72.7V). The higher peak pulse current (68.8A to 70.2A) and 5000W power rating provide enhanced protection without compromising circuit compatibility. Electrical performance is superior while maintaining the same voltage protection window.

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

A: Both P600 and R-6 are through-hole axial packages suitable for standard PCB mounting. The packages are mechanically compatible in most applications. Verify PCB pad spacing and component height clearance for your specific layout before substitution.

Q: Can I substitute the 3KP45-B with the 15KPA45AE3/TR13 or 30KP45A-TP?

A: Yes. Both parts maintain the 45V reverse standoff voltage and compatible clamping characteristics. The significantly higher power ratings (15kW and 30kW) provide enhanced transient suppression capability. These are suitable for applications where greater protection margin is required or where the original 3kW rating is insufficient.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed are ROHS3 compliant and meet the same environmental standards as the original 3KP45-B.

Q: Which substitute part should I select for automotive applications?

A: The 5KP45AHE3/54 and 5KP45AHE3/73 (Vishay) are qualified to AEC-Q101 automotive standards. These parts maintain the same electrical characteristics as standard 5KP45A variants while meeting automotive qualification requirements.

Q: What determines whether a part can substitute for the 3KP45-B?

A: Substitution is determined by matching the 45V reverse standoff voltage, maintaining compatible breakdown voltage (47.39V to 50.3V), clamping voltage (72.7V to 77.4V), and ensuring peak pulse current and power rating meet or exceed the original 41.3A and 3000W specifications. Through-hole mounting and operating temperature range (-55°C ~ 175°C) must also be maintained.

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