5KP18 Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The 5KP18 is a unidirectional transient voltage suppressor diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. This component features a 18V reverse standoff voltage rating with 5000W peak pulse power handling capability in a through-hole P600 axial package. The 5KP18 is classified as obsolete, necessitating identification of active equivalent and substitute parts that maintain functional compatibility for new designs and replacement applications.

Key Parameters

Parameter	Value	Unit
Manufacturer Part Number	5KP18	—
Manufacturer	Littelfuse Inc.	—
Category	Transient Voltage Suppressors (TVS)	—
Type	Zener	—
Unidirectional Channels	1	—
Voltage - Reverse Standoff (Typ)	18	V
Voltage - Breakdown (Min)	18.95	V
Voltage - Clamping (Max) @ Ipp	30.66	V
Power - Peak Pulse	5000	W
Operating Temperature Range	-55 to 175	°C
Mounting Type	Through Hole	—
Package / Case	P600, Axial	—
Product Status	Obsolete	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the 5KP18 is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Voltage - Reverse Standoff (Typ): 18V nominal
Voltage - Breakdown (Min): 18.95V minimum
Power - Peak Pulse: 5000W (5kW) rating
Unidirectional operation (single channel)
Through-hole mounting configuration
Operating temperature range compatibility (-55°C to 175°C minimum)
RoHS3 compliance

Package Compatibility Levels:

Direct package match: P600 axial (highest compatibility)
Alternative packages: DO-201, DO-15 (DO-204AC) with functional equivalence but different form factors

Substitute parts are grouped into two categories based on package type and electrical performance alignment with the original 5KP18 specification.

Parameter Comparison

Parameter	5KP18	5KP18A	SLD18U-017-B	5KP18A-TP	5KP18E3/TR13	1.5KE18A	P6KE20A	SA15A-B
Voltage - Reverse Standoff (Typ)	18V	18V	18V	18V	18V	15.3V	17.1V	15V
Voltage - Breakdown (Min)	18.95V	20V	20V	20V	20V	17.1V	19V	16.7V
Voltage - Clamping (Max) @ Ipp	30.66V	29.2V	29.2V	29.2V	32.2V	25.5V	27.7V	24.4V
Power - Peak Pulse	5000W	5000W	5000W	5000W	5000W	1500W	600W	500W
Current - Peak Pulse (10/1000µs)	—	171A	174.7A	—	155A	60A	22A	20.9A
Operating Temperature Range	-55 to 175°C	-50 to 175°C	-55 to 175°C	-55 to 175°C	-55 to 175°C	-55 to 175°C	-50 to 175°C	-55 to 175°C
Package / Case	P600, Axial	P600, Axial	P600, Axial	R-6, Axial	P600, Axial	DO-201AA, DO-27, Axial	DO-204AC, DO-15, Axial	DO-204AC, DO-15, Axial
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	—	ROHS3 Compliant

Engineering Selection Recommendations

Category 1: Direct Package & Electrical Equivalents (P600 Package, 5000W Rating)

The following parts maintain the original P600 axial package and 5000W power rating, providing direct mechanical and electrical substitution:

5KP18A (Diotec Semiconductor): Active status, 18V standoff, 29.2V clamping, 171A peak pulse current, ROHS3 compliant, -50 to 175°C operating range
SLD18U-017-B (Littelfuse Inc.): Active status, 18V standoff, 29.2V clamping, 174.7A peak pulse current, AEC-Q101 automotive qualified, ROHS3 compliant, -55 to 175°C operating range
5KP18A-TP (Micro Commercial Co): Active status, 18V standoff, 29.2V clamping, 5000W rating, ROHS3 compliant, -55 to 175°C operating range, supplied in cut tape packaging
5KP18E3/TR13 (Microchip Technology): Active status, 18V standoff, 32.2V clamping, 155A peak pulse current, 5000W rating, ROHS3 compliant, -55 to 175°C operating range, supplied in tape & reel

Category 2: Reduced Power Rating Alternatives (Lower Power Dissipation)

These parts provide lower power ratings (1500W or 600W) with comparable voltage characteristics, suitable for applications with reduced transient energy requirements:

1.5KE18A (Taiwan Semiconductor Corporation): Active status, 15.3V standoff, 25.5V clamping, 1500W rating, 60A peak pulse current, DO-201 package, ROHS3 compliant, -55 to 175°C operating range
P6KE20A (Fairchild Semiconductor): Active status, 17.1V standoff, 27.7V clamping, 600W rating, 22A peak pulse current, DO-15 package, -50 to 175°C operating range
SA15A-B (Littelfuse Inc.): Active status, 15V standoff, 24.4V clamping, 500W rating, 20.9A peak pulse current, DO-15 package, ROHS3 compliant, -55 to 175°C operating range

Selection Basis:

All recommended substitutes maintain unidirectional operation, through-hole mounting, and RoHS3 compliance. Category 1 parts are preferred for direct replacement where PCB layout and mechanical constraints match the original P600 package. Category 2 parts are suitable where circuit design accommodates lower power dissipation or alternative package geometries. All active-status parts ensure long-term supply availability and manufacturing support.

Frequently Asked Questions (FAQ)

Q: Can 5KP18A directly replace 5KP18 in existing designs?

A: Yes. The 5KP18A maintains identical 18V reverse standoff voltage, 5000W peak pulse power rating, and P600 axial package configuration. Electrical performance is equivalent with 29.2V clamping voltage compared to the original 30.66V, representing a 4.7% reduction within acceptable design margins for general-purpose overvoltage protection.

Q: What is the difference between P600 and DO-201 packages?

A: P600 and DO-201 are both through-hole axial packages with different physical dimensions. P600 is larger and accommodates higher current handling. DO-201 is smaller and suitable for space-constrained applications. Both are compatible with standard through-hole PCB assembly processes but require different PCB pad spacing and lead lengths.

Q: Why do some substitutes have lower voltage ratings (15V or 17.1V standoff)?

A: Parts with 15V or 17.1V standoff voltages (1.5KE18A, P6KE20A, SA15A-B) operate at different nominal voltage levels. These are functional alternatives only when circuit design permits operation at lower standoff voltages. They are not direct replacements for 18V-rated applications requiring precise voltage regulation.

Q: Is SLD18U-017-B suitable for automotive applications?

A: Yes. SLD18U-017-B carries AEC-Q101 automotive qualification, making it suitable for automotive-grade applications. Other substitutes lack automotive qualification and should not be used in automotive designs without additional qualification testing.

Q: What does "Active" product status mean for long-term availability?

A: Active status indicates the manufacturer currently produces and supports the part. This ensures continued availability for new orders, technical support, and supply chain reliability. The obsolete 5KP18 status means Littelfuse no longer manufactures this part, making active substitutes necessary for new designs.

Q: Can 1.5KE18A replace 5KP18 in high-energy transient applications?

A: No. The 1.5KE18A has a 1500W peak pulse rating compared to 5KP18's 5000W rating. It cannot dissipate equivalent transient energy and is suitable only for lower-energy applications. Use Category 1 substitutes (5KP18A, SLD18U-017-B, 5KP18A-TP, 5KP18E3/TR13) for equivalent power handling.

Q: Are all substitutes RoHS3 compliant?

A: Most recommended substitutes are ROHS3 compliant. P6KE20A does not list RoHS status in provided specifications. Verify RoHS compliance with the manufacturer if regulatory compliance is required for your application.

Q: What is the significance of peak pulse current (Ipp) ratings?

A: Peak pulse current indicates the maximum current the TVS diode can conduct during a transient event. Higher Ipp values (171A-174.7A for Category 1 parts) indicate better current handling capacity. Lower Ipp values (20.9A-60A for Category 2 parts) indicate reduced transient current capability, limiting use to lower-energy applications.

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