KBU8A Bridge Rectifier Equivalent & Substitute Parts

Part Overview

The KBU8A is a single-phase bridge rectifier diode manufactured by onsemi, rated for 50 V peak reverse voltage and 8 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 charging systems, and AC-to-DC conversion applications where single-phase rectification is required.

Key Parameters

Parameter	Value
Manufacturer Part Number	KBU8A
Manufacturer	onsemi
Category	Diodes
Diode Type	Single Phase
Voltage - Peak Reverse (Max)	50 V
Current - Average Rectified (Io)	8 A
Voltage - Forward (Vf) (Max) @ If	1 V @ 8 A
Current - Reverse Leakage @ Vr	10 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 KBU8A is determined by the following critical parameters:

Voltage Rating: Peak reverse voltage must be 50 V or greater
Current Rating: Average rectified current must be 8 A or greater to handle the same load
Diode Type: Single-phase bridge rectifier configuration
Mounting Type: Through-hole package for PCB compatibility
Operating Temperature Range: Must support -55°C to 150°C or equivalent thermal envelope
Forward Voltage Characteristics: Forward voltage drop at rated current should not exceed design margins

Parts are grouped into two categories: direct equivalents (matching 8 A current rating) and higher-current alternatives (exceeding 8 A rating for applications requiring additional thermal margin or future design flexibility).

Parameter Comparison

Part Number	Manufacturer	Voltage - Peak Reverse (Max)	Current - Average Rectified (Io)	Voltage - Forward (Vf) (Max) @ If	Current - Reverse Leakage @ Vr	Operating Temperature	Package / Case	Product Status
KBU8A	onsemi	50 V	8 A	1 V @ 8 A	10 µA @ 50 V	-55°C ~ 150°C	4-SIP, KBU	Obsolete
GBU8A	Fairchild Semiconductor	50 V	5.6 A	1 V @ 8 A	5 µA @ 50 V	-50°C ~ 150°C	4-ESIP, GBU	Active
GBU8005-G	Comchip Technology	50 V	8 A	1 V @ 4 A	5 µA @ 50 V	-55°C ~ 150°C	4-SIP, GBU	Active
GBU6005-G	Comchip Technology	50 V	6 A	1 V @ 3 A	10 µA @ 50 V	-55°C ~ 150°C	4-SIP, GBU	Active
GBU4005-G	Comchip Technology	50 V	4 A	1 V @ 2 A	10 µA @ 50 V	-55°C ~ 150°C	4-SIP, GBU	Active
GBU25005-G	Comchip Technology	50 V	25 A	1 V @ 12.5 A	10 µA @ 50 V	-55°C ~ 150°C	4-SIP, GBU	Active
KBL4005-G	Comchip Technology	50 V	4 A	1.1 V @ 4 A	10 µA @ 50 V	-55°C ~ 150°C	4-SIP, KBL	Active
KBU35005-G	Comchip Technology	50 V	35 A	1.1 V @ 17.5 A	10 µA @ 50 V	-55°C ~ 150°C	4-SIP, KBU	Obsolete

Engineering Selection Recommendations

Direct Equivalent (Preferred for Drop-In Replacement):

GBU8005-G from Comchip Technology is the primary substitute. It matches the 8 A current rating, maintains 50 V voltage rating, and is active in production. The package footprint (4-SIP, GBU) is mechanically compatible with KBU8A applications. RoHS3 compliance and unlimited moisture sensitivity level (MSL 1) provide regulatory alignment for modern manufacturing environments.

Alternative with Reduced Current Rating:

GBU8A from Fairchild Semiconductor is active and provides 50 V rating with forward voltage characteristics matching the original specification. However, the 5.6 A average rectified current is below the KBU8A rating and should only be selected for applications where the actual load current does not exceed 5.6 A. The operating temperature range (-50°C to 150°C) has a reduced lower limit compared to the original specification.

Higher Current Alternatives:

GBU25005-G and KBU35005-G provide 25 A and 35 A ratings respectively. These are suitable for designs requiring additional thermal margin or where future current demands may increase. Both maintain 50 V rating and -55°C to 150°C operating range. GBU25005-G is active in production; KBU35005-G is obsolete.

Not Recommended for Direct Substitution:

GBU6005-G (6 A) and GBU4005-G (4 A) fall below the 8 A specification and are suitable only for applications with reduced current requirements. KBL4005-G has a higher forward voltage drop (1.1 V @ 4 A) and lower current rating, making it unsuitable for KBU8A replacement.

Frequently Asked Questions (FAQ)

Q: Can GBU8A replace KBU8A directly?

A: GBU8A is electrically compatible at 50 V rating but has a reduced average rectified current of 5.6 A versus the original 8 A specification. It is suitable only if your application current does not exceed 5.6 A. The operating temperature lower limit is -50°C instead of -55°C.

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

A: Both GBU and KBU are 4-SIP through-hole bridge rectifier packages with identical mechanical footprints. The designations reflect different manufacturer product lines. GBU8005-G and KBU8A are mechanically interchangeable in PCB layouts.

Q: Is GBU8005-G a true equivalent to KBU8A?

A: GBU8005-G matches the critical electrical parameters: 50 V peak reverse voltage, 8 A average rectified current, and -55°C to 150°C operating range. It is active in production and RoHS3 compliant, making it the recommended direct substitute.

Q: Can I use a higher-current part like GBU25005-G instead of KBU8A?

A: Yes. Higher-current ratings provide additional thermal margin and are electrically compatible. The 25 A rating accommodates the 8 A requirement with headroom. This approach is valid for new designs or redesigns where thermal performance is a consideration.

Q: Why is KBU35005-G listed if it is obsolete?

A: KBU35005-G is included because it was listed in the original KBU8A substitute cross-reference data. However, as an obsolete part, GBU25005-G (active, 25 A) is the preferred higher-current alternative.

Q: What compliance certifications should I verify for my application?

A: All recommended active substitutes carry RoHS3 compliance and REACH unaffected status. Verify ECCN (EAR99) and HTSUS (8541.10.0080) classifications match your export or procurement requirements.

Q: Does package type affect thermal performance?

A: Both 4-SIP (KBU and GBU) packages have identical mechanical dimensions and thermal characteristics. Package type does not impact thermal performance for these bridge rectifier applications.

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