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

Part Overview

The 5KP18-B is a unidirectional transient voltage suppressor diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. This component features an 18V reverse standoff voltage with a 30.66V maximum clamping voltage and 5000W peak pulse power rating in a through-hole P600 axial package. The 5KP18-B is classified as obsolete, necessitating identification of functionally equivalent active alternatives that maintain electrical and mechanical compatibility for new designs and production continuity.

Key Parameters

Parameter	5KP18-B
Manufacturer	Littelfuse Inc.
Type	Zener TVS Diode, Unidirectional
Voltage - Reverse Standoff (Typ)	18V
Voltage - Breakdown (Min)	18.95V
Voltage - Clamping (Max) @ Ipp	30.66V
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 of the 5KP18-B is determined by the following critical parameters:

Primary Substitution Criteria:

Voltage - Reverse Standoff: 18V nominal
Voltage - Clamping (Max) @ Ipp: 29.2V to 32.2V range
Power - Peak Pulse: 5000W (5kW)
Package / Case: P600, Axial (preferred for direct mechanical compatibility)
Unidirectional Channels: 1
Type: Zener TVS Diode
RoHS3 Compliance

Secondary Substitution Criteria (Lower Power Rating):

Voltage - Reverse Standoff: 15V to 18V
Voltage - Clamping (Max) @ Ipp: 24.4V to 27.7V
Power - Peak Pulse: 600W to 1500W
Package / Case: DO-15 or DO-201 (different mechanical form factor)
Applications where reduced power dissipation is acceptable

Substitute parts are grouped into two categories: direct replacements maintaining P600 package and 5000W power rating, and functional alternatives with reduced power ratings in alternative packages suitable for lower-energy transient suppression requirements.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (Typ)	Voltage - Breakdown (Min)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Package / Case	Operating Temperature	Product Status	RoHS Status
5KP18-B	Littelfuse Inc.	18V	18.95V	30.66V	—	5000W	P600, Axial	-55°C ~ 175°C	Obsolete	ROHS3 Compliant
5KP18A	Diotec Semiconductor	18V	20V	29.2V	171A	5000W	P600, Axial	-50°C ~ 175°C	Active	ROHS3 Compliant
5KP18A-B	Littelfuse Inc.	18V	20V	29.2V	174.7A	5000W	P600, Axial	-55°C ~ 175°C	Active	ROHS3 Compliant
SLD18U-017-B	Littelfuse Inc.	18V	20V	29.2V	174.7A	5000W	P600, Axial	-55°C ~ 175°C	Active	ROHS3 Compliant
5KP18A-TP	Micro Commercial Co	18V	20V	29.2V	—	5000W	R-6, Axial	-55°C ~ 175°C	Active	ROHS3 Compliant
5KP18E3/TR13	Microchip Technology	18V	20V	32.2V	155A	5000W	P600, Axial	-55°C ~ 175°C	Active	ROHS3 Compliant
1.5KE18A	Taiwan Semiconductor Corporation	15.3V	17.1V	25.5V	60A	1500W	DO-201AA, Axial	-55°C ~ 175°C	Active	ROHS3 Compliant
1.5KE20A	Taiwan Semiconductor Corporation	17.1V	19V	27.7V	56A	1500W	DO-201AA, Axial	-55°C ~ 175°C	Active	ROHS3 Compliant
P6KE20A	Fairchild Semiconductor	17.1V	19V	27.7V	22A	600W	DO-15, Axial	-50°C ~ 175°C	Active	—
SA15A-B	Littelfuse Inc.	15V	16.7V	24.4V	20.9A	500W	DO-204AC, Axial	-55°C ~ 175°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Replacement (P600 Package, 5000W Rating):

The 5KP18A-B (Littelfuse Inc.) and 5KP18A (Diotec Semiconductor) are the primary direct replacements for the obsolete 5KP18-B. Both maintain identical reverse standoff voltage (18V), equivalent clamping voltage (29.2V), full 5000W power rating, and P600 axial package compatibility. The 5KP18A-B offers extended temperature range (-55°C to 175°C) matching the original specification and is available in active production status with ROHS3 compliance. The SLD18U-017-B (Littelfuse Inc.) provides equivalent electrical performance with automotive-grade qualification (AEC-Q101) for applications requiring automotive reliability standards.

Alternative with Enhanced Clamping Performance:

The 5KP18E3/TR13 (Microchip Technology) maintains the 18V reverse standoff and 5000W power rating in P600 package but features a higher clamping voltage of 32.2V, suitable for applications tolerating slightly elevated transient voltage peaks while maintaining the same power dissipation capability.

Reduced Power Rating Alternatives (1500W and 600W):

The 1.5KE18A and 1.5KE20A (Taiwan Semiconductor Corporation) provide 1500W peak pulse power in DO-201 packages. These are applicable where transient energy levels are lower than the original 5000W specification. The P6KE20A (Fairchild Semiconductor) offers 600W rating in DO-15 package for minimal transient suppression requirements.

Selection Basis:

All recommended substitutes maintain ROHS3 compliance and unidirectional zener TVS diode topology. Selection should prioritize parts with active product status and established supply availability. Package compatibility (P600 vs. alternative packages) determines mechanical fit in existing PCB designs. Power rating selection must align with actual transient energy levels in the application circuit.

Frequently Asked Questions (FAQ)

Q: Can 5KP18A-B directly replace 5KP18-B without PCB modification?

A: Yes. The 5KP18A-B maintains identical P600 axial package dimensions and electrical specifications (18V reverse standoff, 5000W power rating, 29.2V clamping voltage). No PCB layout changes are required for direct substitution.

Q: What is the difference between 5KP18A and 5KP18A-B?

A: Both parts share identical electrical specifications (18V standoff, 29.2V clamping, 5000W power). The primary difference is manufacturer: 5KP18A is from Diotec Semiconductor with -50°C to 175°C operating range, while 5KP18A-B is from Littelfuse Inc. with -55°C to 175°C range. The 5KP18A-B offers extended low-temperature performance.

Q: Why are 1.5KE18A and P6KE20A listed as substitutes if they have lower power ratings?

A: These parts are functional alternatives for applications where peak transient power is below 1500W or 600W respectively. They maintain similar voltage protection characteristics but in different package forms (DO-201 and DO-15). Selection depends on actual circuit transient energy requirements, not maximum rated power.

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

A: Yes. The SLD18U-017-B carries AEC-Q101 automotive qualification, making it appropriate for automotive-grade designs. It maintains identical electrical performance to 5KP18A-B with automotive reliability certification.

Q: What does the "-B" suffix indicate in part numbers like 5KP18-B and 5KP18A-B?

A: The "-B" suffix typically indicates packaging format or manufacturing variant. For 5KP18-B and 5KP18A-B, it denotes bulk packaging. The 5KP18A-TP variant uses cut tape packaging. Electrical specifications remain identical across packaging variants.

Q: Can I use 5KP18E3/TR13 if my circuit requires lower clamping voltage?

A: No. The 5KP18E3/TR13 has a higher maximum clamping voltage (32.2V) compared to the original 5KP18-B (30.66V). If your circuit requires clamping voltage not to exceed 30.66V, use 5KP18A or 5KP18A-B instead, which clamp at 29.2V.

Q: Are all substitute parts RoHS3 compliant?

A: All recommended substitutes except P6KE20A are explicitly listed as ROHS3 compliant. The P6KE20A does not specify RoHS status in the provided data. Verify RoHS compliance requirements with your procurement specifications before selection.

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

A: Both are axial through-hole packages for TVS diodes. P600 is the standard package for 5000W rated devices. R-6 is an alternative axial package used by some manufacturers. Physical dimensions may differ slightly; verify PCB footprint compatibility before substitution.

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