3KP51C-B Equivalent & Substitute Parts

Part Overview

The 3KP51C-B is a transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose voltage clamping applications. This bidirectional zener diode features a 51V reverse standoff voltage with an 86.52V maximum clamping voltage and 36.4A peak pulse current capability in a through-hole P600 axial package. The part is currently obsolete, making equivalent substitutes necessary for new designs and ongoing production requirements.

Key Parameters

Parameter	Value
Voltage - Reverse Standoff (Typ)	51V
Voltage - Breakdown (Min)	53.73V
Voltage - Clamping (Max) @ Ipp	86.52V
Current - Peak Pulse (10/1000µs)	36.4A
Power - Peak Pulse	3000W
Operating Temperature	-55°C ~ 175°C (TJ)
Mounting Type	Through Hole
Package / Case	P600, Axial
Type	Zener
Bidirectional Channels	1

Substitute Part Grouping Explanation

Substitution eligibility for the 3KP51C-B is determined by the following critical parameters:

Voltage - Reverse Standoff: 51V (all substitutes must match)
Voltage - Clamping (Max) @ Ipp: Range 82.4V to 86.52V (acceptable variation)
Operating Temperature: -55°C ~ 175°C (all substitutes must match)
Mounting Type: Through Hole (required)
Type: Zener, Bidirectional (required)
Applications: General Purpose (required)

All identified substitutes maintain the 51V standoff voltage specification and operate within the same temperature range. Clamping voltage variations remain within acceptable engineering tolerances for general-purpose transient suppression. Package variations (P600 vs. R-6) are noted as mechanical differences that may affect board layout compatibility.

Parameter Comparison

Parameter	3KP51C-B (Main)	5KP51CA-B	15KPA51CAE3/TR13	30KP51CA-TP	3KP51CA-TP	5KP51CA-TP
Manufacturer	Littelfuse Inc.	Littelfuse	Microchip Technology	Micro Commercial Co	Micro Commercial Co	Micro Commercial Co
Product Status	Obsolete	Active	Active	Active	Active	Active
Voltage - Reverse Standoff (Typ)	51V	51V	51V	51V	51V	51V
Voltage - Breakdown (Min)	53.73V	56.7V	57V	57V	56.7V	56.7V
Voltage - Clamping (Max) @ Ipp	86.52V	82.4V	82.9V	86.4V	82.4V	82.4V
Current - Peak Pulse (10/1000µs)	36.4A	61.9A	182.1A	—	36.4A	—
Power - Peak Pulse	3000W	5000W	15000W	30000W	3000W	5000W
Operating Temperature	-55°C ~ 175°C	-55°C ~ 175°C	-55°C ~ 175°C	-55°C ~ 175°C	-55°C ~ 175°C	-55°C ~ 175°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	P600, Axial	P600, Axial	P600, Axial	R-6, Axial	R-6, Axial	R-6, Axial
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	—	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	—	1 (Unlimited)

Engineering Selection Recommendations

For direct replacement of the obsolete 3KP51C-B, the following selection criteria apply:

Package-Compatible Substitutes (P600 Axial):

5KP51CA-B (Littelfuse, Active): Maintains identical package geometry with increased power rating (5kW vs. 3kW) and higher peak pulse current (61.9A vs. 36.4A). ROHS3 compliant with MSL 1 rating.
15KPA51CAE3/TR13 (Microchip Technology, Active): Provides significantly higher power dissipation (15kW) and peak pulse current (182.1A) in P600 package. ROHS3 compliant, REACH unaffected.

Alternative Package Substitutes (R-6 Axial):

30KP51CA-TP (Micro Commercial Co, Active): Highest power rating (30kW) with R-6 package requiring board layout modification. ROHS3 compliant, REACH unaffected.
3KP51CA-TP (Micro Commercial Co, Active): Matches original power rating (3kW) and peak pulse current (36.4A) with R-6 package. REACH unaffected.
5KP51CA-TP (Micro Commercial Co, Active): Intermediate power rating (5kW) with R-6 package. ROHS3 compliant, REACH unaffected.

All substitutes maintain the 51V standoff voltage, -55°C to 175°C operating temperature range, and general-purpose application classification. Selection between P600 and R-6 packages depends on existing board layout constraints and mechanical compatibility requirements.

Frequently Asked Questions (FAQ)

Q: Can I use a higher power-rated TVS diode as a substitute? A: Yes. The 5KP51CA-B, 15KPA51CAE3/TR13, 30KP51CA-TP, and 5KP51CA-TP all provide equal or greater power dissipation while maintaining the 51V standoff voltage specification. Higher power ratings do not compromise circuit protection and provide additional margin for transient events.

Q: What is the difference between P600 and R-6 packages? A: Both are through-hole axial packages with different mechanical dimensions. P600 is the original package for the 3KP51C-B. R-6 packages (used by 30KP51CA-TP, 3KP51CA-TP, and 5KP51CA-TP) require verification of board layout compatibility and lead spacing before substitution.

Q: Are all substitutes RoHS3 compliant? A: Most substitutes are ROHS3 compliant. The 3KP51CA-TP does not specify RoHS status in the provided data. Verify RoHS compliance requirements for your application before selection.

Q: What does MSL 1 (Unlimited) mean? A: Moisture Sensitivity Level 1 indicates the component has unlimited shelf life and requires no special moisture control during storage or handling, making it suitable for standard manufacturing environments.

Q: Can I substitute the 3KP51C-B with the 15KPA51CAE3/TR13 in a space-constrained design? A: The 15KPA51CAE3/TR13 maintains the same P600 axial package as the original 3KP51C-B, so board layout compatibility is preserved. The higher power rating (15kW vs. 3kW) provides enhanced transient suppression capability without mechanical constraints.

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