KBU4J Bridge Rectifier Equivalent & Substitute Parts

Part Overview

The KBU4J is a single-phase bridge rectifier diode manufactured by onsemi, rated for 600 V peak reverse voltage and 4 A average rectified current. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. Bridge rectifiers in this voltage and current class are widely used in power supply circuits, battery chargers, and industrial rectification applications where single-phase AC-to-DC conversion is required.

Key Parameters

Parameter	KBU4J
Manufacturer	onsemi
Diode Type	Single Phase
Technology	Standard
Voltage - Peak Reverse (Max)	600 V
Current - Average Rectified (Io)	4 A
Voltage - Forward (Vf) (Max) @ If	1 V @ 4 A
Current - Reverse Leakage @ Vr	5 µA @ 50 V
Operating Temperature Range	-55°C ~ 150°C (TJ)
Mounting Type	Through Hole
Package / Case	4-SIP, KBU
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility for the KBU4J is determined by the following critical parameters:

Voltage Rating: Peak reverse voltage must be 600 V or higher
Current Rating: Average rectified current must meet or exceed 4 A
Diode Type: Single-phase bridge rectifier configuration
Mounting Type: Through-hole package required for mechanical compatibility
Package Family: KBU or GBU package families maintain physical and electrical compatibility
Operating Temperature: Must support the -55°C to 150°C range or equivalent

Substitute parts are grouped into two categories:

Direct Equivalent: GBU4J (Fairchild Semiconductor) — matches the 4 A current rating and 600 V voltage specification with identical forward voltage characteristics.

Similar Equivalents: GBU2506-G, GBU406-G, GBU606-G, and GBU806-G (Comchip Technology) — all rated for 600 V with current ratings ranging from 4 A to 8 A, providing functional substitution with enhanced current capacity options.

Parameter Comparison

Parameter	KBU4J (onsemi)	GBU4J (Fairchild)	GBU406-G (Comchip)	GBU2506-G (Comchip)	GBU606-G (Comchip)	GBU806-G (Comchip)
Voltage - Peak Reverse (Max)	600 V	600 V	600 V	600 V	600 V	600 V
Current - Average Rectified (Io)	4 A	2.8 A	4 A	4.2 A	6 A	8 A
Voltage - Forward (Vf) (Max) @ If	1 V @ 4 A	1 V @ 4 A	1 V @ 2 A	1 V @ 12.5 A	1 V @ 3 A	1 V @ 4 A
Current - Reverse Leakage @ Vr	5 µA @ 50 V	5 µA @ 600 V	10 µA @ 600 V	10 µA @ 600 V	10 µA @ 600 V	10 µA @ 600 V
Operating Temperature Range	-55°C ~ 150°C	-50°C ~ 150°C	-55°C ~ 150°C	-55°C ~ 150°C	-55°C ~ 150°C	-55°C ~ 150°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	4-SIP, KBU	4-ESIP, GBU	4-SIP, GBU	4-SIP, GBU	4-SIP, GBU	4-SIP, GBU
Product Status	Obsolete	Active	Active	Active	Active	Active

Engineering Selection Recommendations

GBU4J (Fairchild Semiconductor) is the primary direct equivalent for KBU4J replacement. It maintains identical voltage and forward voltage specifications with active product status. The current rating of 2.8 A is below the original 4 A specification; this part is suitable only for applications where the actual load current does not exceed 2.8 A.

GBU406-G (Comchip Technology) provides exact current and voltage matching at 4 A and 600 V with active product status and RoHS3 compliance. This part is suitable for direct substitution in applications requiring the full 4 A rating.

GBU2506-G (Comchip Technology) offers 4.2 A current capacity with 600 V rating and active product status. RoHS3 compliance and enhanced reverse leakage specification (10 µA @ 600 V) make this suitable for applications requiring slightly higher current margin.

GBU606-G and GBU806-G (Comchip Technology) provide 6 A and 8 A current ratings respectively, both at 600 V. These parts are suitable for applications where higher current capacity is beneficial or required, with active product status and RoHS3 compliance.

All substitute parts maintain through-hole mounting compatibility and operate within the -55°C to 150°C temperature range or equivalent.

Frequently Asked Questions (FAQ)

Q: Can GBU4J replace KBU4J directly?

A: GBU4J matches the voltage rating (600 V) and forward voltage characteristics (1 V @ 4 A) of the KBU4J. However, its average rectified current rating is 2.8 A, which is below the original 4 A specification. Substitution is valid only if the application's actual current demand does not exceed 2.8 A.

Q: What is the difference between KBU and GBU package families?

A: Both KBU and GBU are 4-pin single-phase bridge rectifier packages with through-hole mounting. The KBU4J uses a 4-SIP package, while GBU variants use either 4-SIP or 4-ESIP configurations. Physical dimensions and pin spacing are compatible for PCB mounting purposes.

Q: Are the Comchip GBU parts suitable replacements?

A: Yes. GBU406-G, GBU2506-G, GBU606-G, and GBU806-G all meet or exceed the KBU4J specifications for voltage (600 V) and current (4 A minimum). All are active products with RoHS3 compliance and identical operating temperature ranges.

Q: What does "obsolete" status mean for the KBU4J?

A: Obsolete status indicates that onsemi has discontinued manufacturing the KBU4J. Substitute parts from active manufacturers (Fairchild Semiconductor and Comchip Technology) are necessary for new designs and ongoing procurement.

Q: Can I use a higher current-rated part like GBU806-G (8 A) instead of the 4 A KBU4J?

A: Yes. Higher current-rated bridge rectifiers are functionally compatible in applications designed for 4 A operation. The 8 A part will operate safely at lower current levels. This approach provides additional design margin and may improve thermal performance.

Q: Are there compliance differences between substitute parts?

A: GBU406-G, GBU2506-G, GBU606-G, and GBU806-G are all RoHS3 compliant. The original KBU4J compliance status is not specified in the provided data. All substitute parts carry REACH Unaffected and EAR99 ECCN classifications.

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