KBU4G Bridge Rectifier Equivalent & Substitute Parts

Part Overview

The KBU4G is a single-phase bridge rectifier manufactured by onsemi, rated for 400 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. The KBU4G features through-hole mounting in a 4-SIP KBU package and operates across a temperature range of -55°C to 150°C.

Key Parameters

Parameter	Value
Diode Type	Single Phase
Technology	Standard
Voltage - Peak Reverse (Max)	400 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	-55°C ~ 150°C (TJ)
Mounting Type	Through Hole
Package / Case	4-SIP, KBU

Substitute Part Grouping Explanation

Substitution for the KBU4G is determined by the following critical parameters:

Voltage Rating: Peak reverse voltage must be 400 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 mounting required
Package Compatibility: Physical form factor must accommodate 4-SIP or equivalent GBU package footprint
Operating Temperature Range: Must support -55°C to 150°C or equivalent range

Substitute parts are grouped into two categories:

Direct Equivalent (GBU4G): Identical voltage and current ratings with active product status.

Higher Current Capacity Substitutes (GBU404-G, GBU604-G, GBU804-G, GBU2504-G): Parts with 400 V voltage rating and current ratings of 4 A or greater, providing design flexibility for applications requiring higher current handling or future design margin.

Parameter Comparison

Part Number	Manufacturer	Product Status	Voltage - Peak Reverse (Max)	Current - Average Rectified (Io)	Voltage - Forward (Vf) (Max) @ If	Current - Reverse Leakage @ Vr	Operating Temperature	Package / Case	Mounting Type
KBU4G	onsemi	Obsolete	400 V	4 A	1 V @ 4 A	5 µA @ 50 V	-55°C ~ 150°C	4-SIP, KBU	Through Hole
GBU4G	Fairchild Semiconductor	Active	400 V	2.8 A	1 V @ 4 A	5 µA @ 400 V	-50°C ~ 150°C	4-ESIP, GBU	Through Hole
GBU404-G	Comchip Technology	Active	400 V	4 A	1 V @ 2 A	10 µA @ 400 V	-55°C ~ 150°C	4-SIP, GBU	Through Hole
GBU604-G	Comchip Technology	Active	400 V	6 A	1 V @ 3 A	10 µA @ 400 V	-55°C ~ 150°C	4-SIP, GBU	Through Hole
GBU804-G	Comchip Technology	Active	400 V	8 A	1 V @ 4 A	10 µA @ 400 V	-55°C ~ 150°C	4-SIP, GBU	Through Hole
GBU2504-G	Comchip Technology	Active	400 V	25 A	1 V @ 12.5 A	10 µA @ 400 V	-55°C ~ 150°C	4-SIP, GBU	Through Hole

Engineering Selection Recommendations

Primary Substitute: GBU404-G (Comchip Technology) provides the closest electrical match with identical 400 V / 4 A ratings, matching operating temperature range, and active product status with RoHS3 compliance.

Alternative Substitutes: GBU604-G and GBU804-G offer higher current capacity (6 A and 8 A respectively) while maintaining 400 V voltage rating and active product status. These are suitable for applications requiring design margin or future current headroom.

Secondary Option: GBU4G (Fairchild Semiconductor) maintains active product status and 400 V rating but operates at 2.8 A average rectified current, which is below the original 4 A specification. This part is suitable only for applications where the actual circuit current demand is confirmed below 2.8 A.

Higher Current Option: GBU2504-G (Comchip Technology) provides 25 A capacity for applications requiring significantly higher current handling, with active product status and RoHS3 compliance.

All substitute parts maintain through-hole mounting and 4-SIP or equivalent GBU package compatibility. Selection should be based on actual circuit current requirements and compliance certifications required for the end application.

Frequently Asked Questions (FAQ)

Q: Can GBU4G replace KBU4G directly?

A: GBU4G shares the same 400 V voltage rating and 1 V forward voltage specification. However, GBU4G is rated for 2.8 A average rectified current, which is below the KBU4G's 4 A rating. Direct substitution is valid only if the actual circuit current demand does not exceed 2.8 A. The operating temperature range is also slightly narrower (-50°C to 150°C vs. -55°C to 150°C).

Q: What is the difference between GBU404-G and GBU804-G?

A: Both parts maintain the 400 V voltage rating and through-hole mounting. GBU404-G is rated for 4 A average rectified current, matching the KBU4G specification. GBU804-G is rated for 8 A, providing double the current capacity. Selection depends on whether the application requires the exact 4 A rating or benefits from higher current capability.

Q: Are all substitute parts RoHS compliant?

A: GBU404-G, GBU604-G, GBU804-G, and GBU2504-G are all RoHS3 compliant. GBU4G compliance status is not specified in the provided data.

Q: Can I use GBU2504-G in place of KBU4G?

A: GBU2504-G maintains the 400 V voltage rating, through-hole mounting, and operating temperature range. Its 25 A current rating exceeds the KBU4G's 4 A requirement, making it electrically compatible for applications where higher current capacity is acceptable. Package footprint compatibility should be verified for the specific PCB layout.

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

A: Both KBU4G and substitute GBU-series parts use 4-SIP through-hole packages. The KBU4G uses a KBU package variant, while substitutes use GBU package variants. Both are physically compatible with standard 4-SIP through-hole footprints, though minor dimensional variations may exist between manufacturers.

Q: Which substitute offers the best inventory availability?

A: GBU4G (Fairchild Semiconductor) has 1409 pieces in stock. GBU2504-G has 864 pieces, GBU804-G has 891 pieces, GBU404-G has 881 pieces, and GBU604-G has 1019 pieces. All substitutes maintain active product status with adequate stock levels.

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