Equivalent & Substitute Parts for 5KP51 TVS Diode

Part Overview

The 5KP51 is a unidirectional transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. Featuring a 51V reverse standoff voltage and 5000W peak pulse power rating in a through-hole P600 axial package, this component provides robust transient suppression across industrial and commercial circuits.

The 5KP51 is classified as obsolete. Equivalent and substitute parts listed below maintain functional compatibility through matching or closely aligned electrical parameters while offering active product status and improved availability.

Key Parameters

Parameter	5KP51 (Main Part)
Manufacturer	Littelfuse Inc.
Type	Zener TVS Diode, Unidirectional
Voltage - Reverse Standoff (Typ)	51V
Voltage - Breakdown (Min)	53.73V
Voltage - Clamping (Max) @ Ipp	86.52V
Power - Peak Pulse	5000W (5kW)
Mounting Type	Through Hole
Package / Case	P600, Axial
Operating Temperature	-55°C ~ 175°C (TJ)
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility for the 5KP51 is determined by the following critical parameters:

Voltage - Reverse Standoff (Typ): Must be 51V or within the 49V–58.1V range to maintain circuit protection thresholds
Voltage - Clamping (Max) @ Ipp: Must not exceed 92V to ensure adequate transient suppression
Power - Peak Pulse: Must be 1500W or greater to handle transient energy
Mounting Type: Through-hole configuration required
Operating Temperature Range: Must support -55°C to 175°C minimum
Unidirectional Channels: Single channel required
RoHS / Compliance Status: ROHS3 compliance preferred for regulatory alignment

Substitute parts are grouped into two categories:

Category A – Direct Electrical & Package Match (P600 Package, 5000W):

5KP51A (Littelfuse, Active)
5KP51E3/TR13 (Microchip Technology, Active)
5KP51A-TP (Micro Commercial Co, Active)

Category B – Functional Equivalents (Alternative Packages, Reduced Power or Voltage Range):

1.5KE62A (Taiwan Semiconductor Corporation, 1500W, DO-201)
1.5KE68A (Meritek, 1500W, DO-201)
P6KE62A (Diotec Semiconductor, 600W, DO-15)
1N5612 (Microchip Technology, 1500W, Axial G)
P4KE62A-TP (Micro Commercial Co, 400W, DO-41)
P6KE68A (Fairchild Semiconductor, 600W, DO-15)

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (Typ)	Voltage - Breakdown (Min)	Voltage - Clamping (Max) @ Ipp	Power - Peak Pulse	Package / Case	Product Status	RoHS Status
5KP51	Littelfuse Inc.	51V	53.73V	86.52V	5000W	P600, Axial	Obsolete	ROHS3 Compliant
5KP51A	Littelfuse	51V	56.7V	82.4V	5000W	P600, Axial	Active	ROHS3 Compliant
5KP51E3/TR13	Microchip Technology	51V	56.7V	91.1V	5000W	P600, Axial	Active	ROHS3 Compliant
5KP51A-TP	Micro Commercial Co	51V	56.7V	82.4V	5000W	R-6, Axial	Active	ROHS3 Compliant
1.5KE62A	Taiwan Semiconductor Corporation	53V	58.9V	85V	1500W	DO-201AA, Axial	Active	ROHS3 Compliant
1.5KE68A	Meritek	—	64.6V	92V	1500W	DO-201, Axial	Active	—
P6KE62A	Diotec Semiconductor	53V	58.9V	85V	600W	DO-15, Axial	Active	Not applicable
1N5612	Microchip Technology	49V	54V	78.5V	1500W	G, Axial	Active	—
P4KE62A-TP	Micro Commercial Co	53V	58.9V	85V	400W	DO-41, Axial	Active	—
P6KE68A	Fairchild Semiconductor	58.1V	64.6V	92V	600W	DO-15, Axial	Active	—

Engineering Selection Recommendations

Primary Substitutes (Recommended for Direct Replacement):

The 5KP51A, 5KP51E3/TR13, and 5KP51A-TP maintain identical voltage ratings (51V standoff) and 5000W power dissipation, ensuring equivalent circuit protection performance. All three are active products with ROHS3 compliance. Selection among these three depends on packaging availability and supplier lead times. The 5KP51A and 5KP51E3/TR13 use standard P600 packages; the 5KP51A-TP uses an R-6 package variant.

Secondary Substitutes (Functional Equivalents with Trade-offs):

The 1.5KE62A and 1.5KE68A series offer active product status and ROHS3 compliance but reduce peak pulse power to 1500W and use DO-201 packages. These are suitable for applications where transient energy levels are lower or where package footprint constraints permit alternative geometries.

The 1N5612 provides 1500W power rating with a 49V standoff voltage, acceptable for circuits tolerating slightly lower protection thresholds. The P6KE62A and P6KE68A series reduce power to 600W and use DO-15 packages, limiting application to low-energy transient environments.

The P4KE62A-TP offers 400W power dissipation in a DO-41 package, suitable only for minimal transient energy applications.

Compliance Considerations:

All Category A substitutes (5KP51A, 5KP51E3/TR13, 5KP51A-TP) maintain ROHS3 compliance matching the original 5KP51. Category B substitutes vary in compliance documentation; verify RoHS and REACH status against specific procurement requirements before selection.

Frequently Asked Questions (FAQ)

Q: Can the 5KP51A directly replace the 5KP51 without circuit modification?

A: Yes. The 5KP51A maintains identical voltage ratings (51V standoff), clamping voltage (82.4V), and power dissipation (5000W). Both use P600 axial packages and support the same operating temperature range (-55°C to 175°C). No circuit redesign is required.

Q: What is the primary difference between Category A and Category B substitutes?

A: Category A substitutes (5KP51A, 5KP51E3/TR13, 5KP51A-TP) preserve the 5000W power rating and 51V voltage specification, ensuring identical protection performance. Category B substitutes reduce power dissipation to 1500W or lower and may use alternative packages (DO-201, DO-15, DO-41), requiring circuit evaluation to confirm transient energy compatibility.

Q: Can I use the 1.5KE62A in place of the 5KP51 if my circuit has lower transient energy?

A: The 1.5KE62A is electrically compatible (53V standoff, 85V clamping) but reduces peak pulse power from 5000W to 1500W. Use only if circuit transient energy analysis confirms that 1500W dissipation is sufficient. Verify package footprint compatibility; the 1.5KE62A uses DO-201 instead of P600.

Q: Does the 1N5612 work as a substitute despite its 49V standoff voltage?

A: The 1N5612 has a lower standoff voltage (49V vs. 51V), which may allow earlier triggering in some circuits. It provides 1500W power and 78.5V clamping voltage. Use only if circuit protection thresholds tolerate the lower standoff specification.

Q: Are all substitute parts RoHS compliant?

A: Category A substitutes (5KP51A, 5KP51E3/TR13, 5KP51A-TP) are ROHS3 compliant. Category B substitutes have varying compliance status. Verify RoHS and REACH documentation for specific parts before procurement.

Q: What package considerations apply when selecting substitutes?

A: The 5KP51 uses a P600 axial package. The 5KP51A and 5KP51E3/TR13 maintain this package. The 5KP51A-TP uses an R-6 variant. Category B substitutes use DO-201, DO-15, or DO-41 packages, requiring PCB layout verification and potential mechanical redesign. Confirm footprint compatibility before selection.

Q: Can I mix substitute parts in the same circuit design?

A: No. Use a single substitute part number throughout a design to ensure consistent protection performance and simplify procurement and inventory management.

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