Equivalent & Substitute Parts for 3KP33-B TVS Diode

Part Overview

The 3KP33-B is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Littelfuse, designed for general-purpose transient protection applications. This component features a 33V reverse standoff voltage with a 55.97V maximum clamping voltage and 56.3A peak pulse current capability in a P600 axial through-hole package. The product is currently obsolete, making equivalent and substitute parts necessary for ongoing system support and new designs requiring similar protection characteristics.

Key Parameters

Parameter	Value
Voltage - Reverse Standoff (Typ)	33V
Voltage - Breakdown (Min)	34.79V
Voltage - Clamping (Max) @ Ipp	55.97V
Current - Peak Pulse (10/1000µs)	56.3A
Power - Peak Pulse	3000W
Mounting Type	Through Hole
Package / Case	P600, Axial
Operating Temperature	-55°C ~ 175°C (TJ)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the 3KP33-B is determined by the following critical parameters:

Voltage Rating: Reverse standoff voltage must be 33V with breakdown voltage between 34.79V and 36.9V
Package Type: Through-hole axial mounting (P600 or R-6 packages acceptable)
Clamping Voltage: Maximum clamping voltage range 53.3V to 58.5V @ Ipp
Peak Pulse Current: Minimum 56.3A capability at 10/1000µs pulse
Power Dissipation: Minimum 3000W peak pulse power rating
Temperature Range: Operating range -55°C to 175°C
Compliance: ROHS3 compliant

Substitute parts are grouped into three categories based on power rating and current handling capability: 5kW class (5KP series), 15kW class (15KPA series), and 30kW class (30KP series). All maintain the 33V voltage rating and through-hole axial package configuration.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Package / Case	Product Status
3KP33-B	Littelfuse	33V	55.97V	56.3A	3000W	P600, Axial	Obsolete
5KP33A-B	Littelfuse Inc.	33V	53.3V	95.7A	5000W	P600, Axial	Active
15KPA33AE3/TR13	Microchip Technology	33V	54.7V	276.1A	15000W	P600, Axial	Active
30KP33A-TP	Micro Commercial Co	33V	58.5V	—	30000W	R-6, Axial	Active
5KP33A-E3/54	Vishay General Semiconductor	33V	53.3V	93.8A	5000W	P600, Axial	Active
5KP33A-E3/73	Vishay General Semiconductor	33V	53.3V	93.8A	5000W	P600, Axial	Active
5KP33A-TP	Micro Commercial Co	33V	53.3V	—	5000W	R-6, Axial	Active
5KP33AHE3/54	Vishay General Semiconductor	33V	53.3V	93.8A	5000W	P600, Axial	Active
BZW50-33	STMicroelectronics	33V	76V	789A (8/20µs)	5000W	R-6, Axial	Active
BZW50-33RL	STMicroelectronics	33V	76V	789A (8/20µs)	5000W	R-6, Axial	Active

Engineering Selection Recommendations

Direct Replacement (Same Power Class): The 5KP33A-B, 5KP33A-E3/54, 5KP33A-E3/73, and 5KP33AHE3/54 provide the closest functional equivalence to the 3KP33-B. All maintain the 33V voltage rating, P600 package configuration, and 5000W power rating. The 5KP33A-B from Littelfuse offers continuity with the original manufacturer. The Vishay TransZorb® variants (5KP33A-E3/54, 5KP33A-E3/73, 5KP33AHE3/54) are active products with ROHS3 compliance and higher peak pulse current (93.8A). The 5KP33AHE3/54 includes AEC-Q101 automotive qualification.

Higher Power Capability: The 15KPA33AE3/TR13 from Microchip Technology and 30KP33A-TP from Micro Commercial Co provide enhanced transient protection with 15kW and 30kW peak pulse power ratings respectively. These are suitable for applications requiring greater surge protection margin.

Alternative Package Consideration: The BZW50-33 and BZW50-33RL from STMicroelectronics (TRANSIL™ series) offer R-6 axial package configuration with higher clamping voltage (76V) and significantly higher peak pulse current (789A at 8/20µs). These are applicable where package footprint compatibility with R-6 exists.

All substitute parts maintain ROHS3 compliance, -55°C to 175°C operating temperature range, and through-hole axial mounting configuration.

Frequently Asked Questions (FAQ)

Q: Can I use a higher power-rated TVS diode as a direct substitute? A: Yes. A TVS diode with higher power rating (5kW, 15kW, or 30kW) can replace the 3000W 3KP33-B provided the voltage rating (33V standoff), package type (through-hole axial), and clamping voltage remain within acceptable circuit limits. Higher power ratings provide additional transient protection margin.

Q: What is the difference between P600 and R-6 packages? A: Both are through-hole axial packages for TVS diodes. P600 and R-6 have different physical dimensions and lead spacing. Verify PCB footprint compatibility before substitution. The 3KP33-B uses P600; R-6 alternatives (5KP33A-TP, 30KP33A-TP, BZW50-33, BZW50-33RL) require matching board layout.

Q: Are Vishay TransZorb® parts (5KP33A-E3/54, 5KP33A-E3/73) interchangeable? A: Yes. Both Vishay variants maintain identical electrical specifications (33V standoff, 53.3V clamping, 93.8A peak pulse, 5000W power). The difference is packaging format (both Cut Tape). Select based on tape reel availability and procurement requirements.

Q: What does AEC-Q101 qualification mean for the 5KP33AHE3/54? A: AEC-Q101 is an automotive electronics qualification standard. The 5KP33AHE3/54 meets automotive-grade reliability requirements and is suitable for automotive and high-reliability applications requiring enhanced qualification documentation.

Q: Can I substitute the BZW50-33 series for the 3KP33-B? A: The BZW50-33 and BZW50-33RL maintain the 33V voltage rating and 5000W power rating but feature higher clamping voltage (76V vs. 55.97V) and significantly higher peak pulse current (789A vs. 56.3A). Substitution is valid if circuit design accommodates the higher clamping voltage and the R-6 package footprint is compatible with your PCB.

Q: Why is the 3KP33-B obsolete? A: The 3KP33-B has been discontinued by Littelfuse. Active alternatives from multiple manufacturers (Littelfuse 5KP series, Vishay TransZorb®, Microchip, STMicroelectronics) provide equivalent or enhanced functionality with ongoing production support and availability.

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