Littelfuse 5KP43 Transient Voltage Suppressor Equivalent & Substitute Parts

Part Overview

The Littelfuse 5KP43 is a unidirectional Zener transient voltage suppressor (TVS) 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 systems.

The 5KP43 is classified as obsolete, necessitating identification of functionally equivalent alternatives from active product lines. Suitable substitutes maintain the core electrical characteristics—43V standoff voltage, 5000W power dissipation capability, and P600 package compatibility—while offering improved availability and extended product support.

Key Parameters

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

Substitute Part Grouping Explanation

Substitution eligibility for the 5KP43 is determined by strict alignment with the following electrical and mechanical parameters:

Primary Substitution Criteria:

Voltage - Reverse Standoff (Typ): 43V ±tolerance
Power - Peak Pulse: 5000W minimum
Package / Case: P600, Axial (through-hole)
Type: Zener, Unidirectional
Operating Temperature Range: -55°C to 175°C minimum

Secondary Compatibility Factors:

Voltage - Breakdown (Min): 45.27V to 50V range
Voltage - Clamping (Max) @ Ipp: 64.8V to 76.7V range
Unidirectional Channels: 1 channel
Mounting Type: Through Hole

Substitutes are grouped into two categories:

Category A - Direct P600 Package Equivalents: Parts maintaining identical P600 axial package geometry and 5000W power rating with 43V standoff voltage specification. These provide pin-for-pin compatibility and identical board layout requirements.

Category B - Functional Equivalents with Package Variation: Parts meeting electrical specifications (43V standoff, 5000W power) but utilizing alternative through-hole packages (DO-201, DO-15). These require board layout modification but maintain electrical performance within acceptable parameters.

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	Product Status
5KP43	Littelfuse	43V	45.27V	72.87V	—	5000W	P600, Axial	Obsolete
5KP43A	Littelfuse Inc.	43V	47.8V	69.4V	74.6A	5000W	P600, Axial	Active
SLD43U-017-B	Littelfuse Inc.	43V	49V	69.4V	74.6A	5000W	P600, Axial	Active
5KP43E3/TR13	Microchip Technology	43V	47.8V	76.7V	65.2A	5000W	P600, Axial	Active
1.5KE47A	Taiwan Semiconductor Corporation	40.2V	44.7V	64.8V	24A	1500W	DO-201AA, Axial	Active
1.5KE51A	Meritek	—	48.5V	70.1V	21.7A	1500W	DO-201, Axial	Active
SA45A-TP	Micro Commercial Co	45V	50V	72.7V	7A	500W	DO-15, Axial	Active
SA40A-TP	Micro Commercial Co	40V	44.4V	64.5V	7.9A	500W	DO-15, Axial	Active
P6KE51A	Fairchild Semiconductor	—	—	—	—	—	—	Active
P6KE56A-TP	Micro Commercial Co	47.8V	53.2V	77V	7.8A	600W	DO-15, Axial	Active

Engineering Selection Recommendations

Tier 1 - Direct Replacement (P600 Package, 5000W Power):

The 5KP43A (Littelfuse Inc.) and SLD43U-017-B (Littelfuse Inc.) are primary substitutes, both maintaining P600 axial package geometry and 5000W peak pulse power rating with 43V standoff voltage. Both parts are active products with ROHS3 compliance and unlimited moisture sensitivity rating (MSL 1). The 5KP43A is available in Cut Tape packaging with 3339 units in stock, while SLD43U-017-B is supplied in Bulk packaging with 995 units available. The SLD43U-017-B carries AEC-Q101 automotive qualification, suitable for applications requiring automotive-grade reliability.

The 5KP43E3/TR13 (Microchip Technology) provides an alternative P600 package solution with identical 43V standoff voltage and 5000W power rating. This part features a higher clamping voltage (76.7V maximum) and is supplied in Tape & Reel packaging with 1076 units in stock. Microchip's active product status and ROHS3 compliance ensure long-term availability.

Tier 2 - Functional Equivalents (Reduced Power Rating):

The 1.5KE47A (Taiwan Semiconductor Corporation) and 1.5KE51A (Meritek) operate at reduced 1500W peak pulse power in DO-201 through-hole packages. These parts are suitable only for applications where 1500W dissipation capacity is sufficient. The 1.5KE47A offers 40.2V standoff voltage with 36829 units in stock, while 1.5KE51A provides 48.5V breakdown voltage with 1529 units available.

Tier 3 - Lower Power Alternatives (DO-15 Package, 500W–600W):

The SA45A-TP, SA40A-TP, and P6KE56A-TP are low-power alternatives in DO-15 packages with 500W to 600W peak pulse ratings. These parts are applicable only to circuits with reduced transient energy requirements. SA45A-TP (45V standoff, 500W) and SA40A-TP (40V standoff, 500W) are general-purpose options, while P6KE56A-TP (47.8V standoff, 600W) carries automotive-grade qualification.

Compliance and Availability:

All recommended substitutes maintain ROHS3 compliance and -55°C to 175°C operating temperature range. Littelfuse-manufactured parts (5KP43A, SLD43U-017-B) offer the highest inventory availability and direct manufacturer support. Microchip's 5KP43E3/TR13 provides an established alternative from a major semiconductor manufacturer.

Frequently Asked Questions (FAQ)

Q: Can the 5KP43 be directly replaced with the 5KP43A?

A: Yes. The 5KP43A is a direct substitute maintaining identical P600 axial package geometry, 43V standoff voltage, and 5000W peak pulse power rating. Both are Littelfuse products with equivalent electrical performance and board-level compatibility.

Q: What is the difference between the 5KP43A and SLD43U-017-B?

A: Both parts maintain P600 package and 5000W power rating with 43V standoff voltage. The primary difference is packaging format: 5KP43A is supplied in Cut Tape, while SLD43U-017-B is supplied in Bulk. The SLD43U-017-B carries AEC-Q101 automotive qualification, making it suitable for automotive applications. Clamping voltage specifications are identical (69.4V maximum).

Q: Can lower-power alternatives like SA45A-TP replace the 5KP43?

A: No, not for equivalent performance. The SA45A-TP operates at 500W peak pulse power compared to the 5KP43's 5000W rating. This part is suitable only for applications with significantly reduced transient energy requirements. Board layout modification is also required due to DO-15 package differences.

Q: What is the significance of the P600 package?

A: The P600 package is a through-hole axial format with specific lead spacing and body dimensions. Direct P600 substitutes (5KP43A, SLD43U-017-B, 5KP43E3/TR13) require no board layout changes. Alternative packages (DO-201, DO-15) have different physical dimensions and require PCB redesign.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All recommended substitutes maintain ROHS3 compliance, meeting environmental and regulatory requirements equivalent to the original 5KP43.

Q: Which substitute offers the best long-term availability?

A: The 5KP43A (Littelfuse Inc.) and 5KP43E3/TR13 (Microchip Technology) are both active products from established manufacturers with extensive distribution networks. The 5KP43A offers the highest current inventory (3339 units) and direct Littelfuse support.

Q: Can the 1.5KE47A be used as a substitute?

A: The 1.5KE47A is a functional alternative only for applications where 1500W peak pulse power is sufficient. It operates at 40.2V standoff voltage in a DO-201 package, requiring board layout modification. This part is not a direct replacement for 5000W applications.

Q: What does "Voltage - Clamping (Max) @ Ipp" mean in the context of substitution?

A: This parameter specifies the maximum voltage across the TVS diode during peak pulse current. Substitutes with clamping voltages within the 64.8V to 76.7V range maintain equivalent transient suppression performance. Significant deviations may affect circuit protection effectiveness.

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