5KP45-B Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The 5KP45-B is a unidirectional Zener-type transient voltage suppressor diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. This component features a 45V reverse standoff voltage with a maximum clamping voltage of 76.34V at peak pulse current, rated for 5000W peak pulse power dissipation in a through-hole P600 axial package. The 5KP45-B is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain compatibility with the P600 package footprint and deliver equivalent voltage suppression characteristics within the specified operating temperature range of -55°C to 175°C.

Key Parameters

Parameter	Value	Unit
Manufacturer Part Number	5KP45-B	—
Manufacturer	Littelfuse Inc.	—
Category	Transient Voltage Suppressors (TVS)	—
Type	Zener	—
Unidirectional Channels	1	—
Voltage - Reverse Standoff (Typ)	45	V
Voltage - Breakdown (Min)	47.39	V
Voltage - Clamping (Max) @ Ipp	76.34	V
Power - Peak Pulse	5000	W
Mounting Type	Through Hole	—
Package / Case	P600, Axial	—
Operating Temperature	-55 to 175	°C
RoHS Status	ROHS3 Compliant	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitute parts for the 5KP45-B are grouped based on the following critical parameters that determine functional equivalence:

Primary Substitution Criteria:

Voltage - Reverse Standoff (Typ): 45V nominal
Voltage - Clamping (Max) @ Ipp: Range 72.7V to 80.3V (within acceptable suppression envelope)
Power - Peak Pulse: 5000W (5kW) rating
Mounting Type: Through Hole
Package / Case: P600 Axial (primary group) or DO-201/DO-15 Axial (alternative group with reduced power handling)
Operating Temperature: -55°C to 175°C
Type: Zener unidirectional

Substitution Groups:

Group 1: Direct P600 Package Equivalents (5000W Rating) Parts maintaining identical P600 axial package and 5000W power rating with 45V standoff voltage.

Group 2: Alternative Package Equivalents (Reduced Power Rating) Parts with DO-201 or DO-15 packages offering lower power ratings (1500W or 600W) suitable for lower-energy transient suppression applications.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (V)	Voltage - Clamping (Max) @ Ipp (V)	Current - Peak Pulse (A)	Power - Peak Pulse (W)	Package / Case	Product Status
5KP45-B	Littelfuse Inc.	45	76.34	—	5000	P600, Axial	Obsolete
5KP45A	Littelfuse Inc.	45	72.7	70.2	5000	P600, Axial	Active
5KP45A-B	Littelfuse Inc.	45	72.7	70.2	5000	P600, Axial	Active
5KP45E3/TR13	Microchip Technology	45	80.3	62.3	5000	P600, Axial	Active
1.5KE47A	Taiwan Semiconductor Corporation	40.2	64.8	24	1500	DO-201AA, Axial	Active
1.5KE51A	Meritek	—	70.1	21.7	1500	DO-201, Axial	Active
SA45A-TP	Micro Commercial Co	45	72.7	7	500	DO-15, Axial	Active
SA40A-TP	Micro Commercial Co	40	64.5	7.9	500	DO-15, Axial	Active
P6KE51A	Fairchild Semiconductor	—	—	—	—	—	Active
P6KE56A-TP	Micro Commercial Co	47.8	77	7.8	600	DO-15, Axial	Active

Engineering Selection Recommendations

Primary Recommendation - Group 1 (P600 Package, 5000W):

The 5KP45A and 5KP45A-B from Littelfuse Inc. are the preferred direct substitutes for the obsolete 5KP45-B. Both parts maintain identical 45V reverse standoff voltage, P600 axial package configuration, and 5000W peak pulse power rating. The 5KP45A offers a maximum clamping voltage of 72.7V with 70.2A peak pulse current, providing equivalent transient suppression performance. Both parts are ROHS3 compliant and carry active product status, ensuring long-term availability and supply chain stability.

The 5KP45E3/TR13 from Microchip Technology is an alternative P600 equivalent with identical 45V standoff voltage and 5000W power rating. This part features a slightly higher maximum clamping voltage of 80.3V at 62.3A peak pulse current, suitable for applications requiring enhanced voltage suppression margin. Microchip's active product status and ROHS3 compliance support production continuity.

Secondary Recommendation - Group 2 (Alternative Packages, Reduced Power):

For applications where lower transient energy levels are acceptable, the 1.5KE47A (Taiwan Semiconductor Corporation) and 1.5KE51A (Meritek) offer 1500W peak pulse power in DO-201 axial packages. The 1.5KE47A maintains a 40.2V reverse standoff voltage with 64.8V maximum clamping voltage. These parts are suitable for lower-energy transient suppression scenarios and are ROHS3 compliant with active product status.

The SA45A-TP from Micro Commercial Co provides a 45V standoff voltage match with 72.7V maximum clamping voltage in a DO-15 axial package, rated for 500W peak pulse power. This part is appropriate for low-energy transient protection applications and carries active product status with REACH compliance.

Compliance and Certification:

All recommended substitute parts maintain ROHS3 compliance and active product status, ensuring regulatory alignment and supply availability. Selection should prioritize parts matching the original P600 package footprint and 5000W power rating for direct functional equivalence in existing circuit designs.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with a different package type (DO-201 or DO-15) in place of the P600 package?

A: No. Package type changes require PCB layout modifications and cannot be used as direct drop-in replacements. The P600 axial package has different lead spacing and mounting hole requirements compared to DO-201 or DO-15 packages. If package substitution is necessary, the circuit board must be redesigned to accommodate the new footprint.

Q: What is the significance of the clamping voltage difference between 5KP45-B (76.34V) and 5KP45A (72.7V)?

A: Both parts maintain the same 45V reverse standoff voltage and 5000W power rating. The clamping voltage represents the maximum voltage across the diode during transient suppression. The 5KP45A's lower clamping voltage (72.7V) provides slightly tighter voltage regulation during transient events, which is acceptable for most general-purpose applications. The difference falls within normal manufacturing tolerances for this device category.

Q: Are the 1.5KE series parts (1.5KE47A, 1.5KE51A) suitable replacements for the 5KP45-B?

A: The 1.5KE series parts are not direct equivalents due to significantly reduced power ratings (1500W versus 5000W) and different package types (DO-201 versus P600). These parts are suitable only for applications with lower transient energy requirements. For circuits designed around the 5KP45-B's 5000W capability, the 1.5KE series will not provide adequate protection.

Q: What does "active product status" mean for substitute parts?

A: Active product status indicates that the manufacturer currently produces and supports the part, ensuring ongoing availability, consistent quality, and long-term supply chain reliability. The obsolete status of the 5KP45-B makes active-status substitutes essential for new designs and production continuity.

Q: Can I use SA45A-TP or SA40A-TP as direct replacements for the 5KP45-B?

A: No. While SA45A-TP matches the 45V standoff voltage and 72.7V clamping voltage, it is rated for only 500W peak pulse power compared to the 5KP45-B's 5000W rating. Additionally, the SA45A-TP uses a DO-15 package instead of P600, requiring PCB redesign. These parts are suitable only for low-energy transient suppression applications.

Q: What is the operating temperature range for substitute parts?

A: All recommended substitute parts maintain the same operating temperature range as the 5KP45-B: -55°C to 175°C (TJ). This ensures thermal performance equivalence across the full operating envelope.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All recommended substitute parts listed carry ROHS3 compliance certification, matching the regulatory status of the original 5KP45-B and ensuring compatibility with modern manufacturing and environmental standards.

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