Littelfuse 5KP43C Transient Voltage Suppressor (TVS) — Equivalent & Substitute Parts

Part Overview

The Littelfuse 5KP43C is a bidirectional transient voltage suppressor diode designed for general-purpose overvoltage protection applications. Featuring a 43V reverse standoff voltage and 5000W peak pulse power rating in a P600 axial through-hole package, this component provides robust transient suppression across industrial and commercial circuits.

The 5KP43C is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this component.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	43	V
Voltage - Breakdown (Min)	45.27	V
Voltage - Clamping (Max) @ Ipp	72.87	V
Power - Peak Pulse	5000	W
Bidirectional Channels	1	—
Mounting Type	Through Hole	—
Package / Case	P600, Axial	—
Operating Temperature	-55 to 175	°C (TJ)
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the 5KP43C is determined by the following critical parameters:

Voltage - Reverse Standoff (Typ): Must be 43V or within acceptable tolerance for the application
Power - Peak Pulse: Must meet or exceed 5000W to maintain protection capability
Package / Case: P600 axial package preferred for direct mechanical and electrical compatibility
Bidirectional Channels: Must be 1 (single bidirectional channel)
Mounting Type: Through-hole configuration required
Operating Temperature Range: Must support -55°C to 175°C (TJ) or equivalent

Substitute parts are grouped into two categories:

Category A — Direct P600 Package Equivalents (5000W): Parts maintaining the same P600 axial package and 5000W power rating with 43V standoff voltage. These provide the highest compatibility for direct replacement.

Category B — Alternative Package Equivalents (Lower Power Ratings): Parts with different packages (DO-201, DO-15) and reduced power ratings (1500W, 600W, 500W) but compatible voltage parameters. These require circuit board layout modification and are suitable only when peak pulse power requirements can be reduced.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (Typ)	Voltage - Clamping (Max) @ Ipp	Power - Peak Pulse	Package / Case	Product Status
5KP43C	Littelfuse	43V	72.87V	5000W	P600, Axial	Obsolete
5KP43CA	Littelfuse Inc.	43V	69.4V	5000W	P600, Axial	Active
SLD43-018-B	Littelfuse Inc.	43V	69.4V	5000W	P600, Axial	Active
5KP43CE3/TR13	Microchip Technology	43V	76.7V	5000W	P600, Axial	Active
1.5KE47CA	Diotec Semiconductor	40.2V	64.8V	1500W	DO-201AA, Axial	Active
1.5KE51CA	Taiwan Semiconductor Corporation	43.6V	70.1V	1500W	DO-201AA, Axial	Active
1.5KE56CA	Taiwan Semiconductor Corporation	47.8V	77V	1500W	DO-201AA, Axial	Active
P6KE47CA	Diotec Semiconductor	40.2V	64.8V	600W	DO-204AC, Axial	Active
P6KE51CA	Taiwan Semiconductor Corporation	43.6V	70.1V	600W	DO-204AC, Axial	Active
SA48CA	Taiwan Semiconductor Corporation	48V	77.4V	500W	DO-204AC, Axial	Active
1N6124	Semtech Corporation	42.6V	80.7V	500W	Axial	Discontinued

Engineering Selection Recommendations

Primary Substitutes (Category A — Recommended)

For applications requiring direct replacement without circuit modification, select from active P600 package equivalents:

5KP43CA (Littelfuse Inc.) — Active status, identical package and power rating, 43V standoff voltage, ROHS3 compliant, widely available
SLD43-018-B (Littelfuse Inc.) — Active status, automotive-grade (AEC-Q101), identical electrical and mechanical specifications, ROHS3 compliant
5KP43CE3/TR13 (Microchip Technology) — Active status, identical package and power rating, 43V standoff voltage, ROHS3 compliant

Secondary Substitutes (Category B — Alternative Packages)

For applications where peak pulse power requirements can be reduced or where circuit board redesign is acceptable:

1.5KE51CA (Taiwan Semiconductor Corporation) — Active status, 43.6V standoff voltage (closest match), 1500W power rating, DO-201 package, ROHS3 compliant
P6KE51CA (Taiwan Semiconductor Corporation) — Active status, 43.6V standoff voltage, 600W power rating, DO-15 package, ROHS3 compliant

Not Recommended

1N6124 (Semtech Corporation) — Discontinued status; avoid for new designs
SA48CA — 48V standoff voltage exceeds 43V specification; suitable only for applications with higher voltage tolerance

All recommended active substitutes maintain ROHS3 compliance and support the -55°C to 175°C operating temperature range.

Frequently Asked Questions (FAQ)

Q: Can 5KP43CA be used as a direct replacement for 5KP43C?

A: Yes. The 5KP43CA is a direct equivalent with identical P600 package, 43V standoff voltage, and 5000W power rating. It is active status and ROHS3 compliant, making it the primary substitute.

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

A: P600 is a larger axial package rated for higher power dissipation (5000W). DO-201 is a smaller axial package rated for 1500W. Direct mechanical substitution is not possible without circuit board modification. DO-201 parts are suitable only when peak pulse power requirements are reduced.

Q: Can I use 1.5KE56CA instead of 5KP43C?

A: 1.5KE56CA has a 47.8V standoff voltage (outside the 43V specification) and 1500W power rating (versus 5000W). It is suitable only if the application can tolerate higher standoff voltage and reduced power handling. Circuit board layout changes are required due to different package (DO-201).

Q: Why is 1N6124 not recommended?

A: 1N6124 is discontinued at DiGi Electronics and has reduced availability. Additionally, its 500W power rating is significantly lower than the 5000W requirement of the original part.

Q: Are all substitute parts ROHS3 compliant?

A: All active-status substitutes listed are ROHS3 compliant. The discontinued 1N6124 has not-applicable RoHS status.

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

A: All recommended substitutes support -55°C to 175°C (TJ) operating temperature, matching the original 5KP43C specification.

Q: Can SLD43-018-B be used in automotive applications?

A: Yes. SLD43-018-B carries automotive-grade qualification (AEC-Q101), making it suitable for automotive and high-reliability applications requiring transient voltage suppression.

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