BU408 Equivalent & Substitute Parts

Part Overview

The BU408 is an NPN bipolar junction transistor manufactured by onsemi, rated for 200V collector-emitter breakdown voltage and 7A maximum collector current in a TO-220-3 through-hole package. This device is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and procurement continuity. The BU408 delivers 60W maximum power dissipation with a 10MHz transition frequency, suitable for general-purpose switching and amplification applications in industrial and consumer electronics.

Substiute Parts

BU408

onsemiIn Stock: 1476BU408 Datasheet

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BU406G

onsemiIn Stock: 1477BU406G Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the BU408 is determined by electrical and mechanical parameter equivalence across the following criteria:

Electrical Parameters (Critical for Function):

• Transistor polarity: NPN configuration
• Maximum collector current: 7A
• Collector-emitter breakdown voltage: 200V
• Maximum power dissipation: 60W
• Transition frequency: 10MHz

Mechanical Parameters (Critical for Installation):

• Mounting type: Through-hole
• Package designation: TO-220-3

The BU406G meets all specified electrical parameters and maintains mechanical compatibility through identical TO-220-3 package geometry and through-hole mounting. Both devices share the same voltage and current ratings, power dissipation capability, and frequency response, establishing direct functional equivalence.

Parameter Comparison

Engineering Selection Recommendations

BU406G as Primary Substitute:

The BU406G is the direct functional equivalent for BU408 applications. Both devices are classified under the same ECCN (EAR99) and REACH status, ensuring regulatory compliance equivalence. The BU406G holds active product status, providing ongoing availability and manufacturing support, whereas the BU408 is obsolete. All critical electrical parameters—collector current, breakdown voltage, power rating, and transition frequency—are identical between the two devices.

The BU406G operates across an extended temperature range of −65°C to 150°C compared to the BU408's maximum operating temperature of 150°C, providing broader thermal operating margin. The BU406G is supplied in tube packaging and maintains TO-220-3 mechanical compatibility, ensuring direct PCB mounting compatibility without design modification.

For new designs or production transitions from BU408-based circuits, the BU406G provides complete electrical and mechanical substitution with the additional benefit of active product status and RoHS3 compliance certification.

Frequently Asked Questions (FAQ)

Q: Can BU406G directly replace BU408 in existing circuit designs?

A: Yes. The BU406G provides direct electrical and mechanical substitution. Both devices share identical collector current (7A), breakdown voltage (200V), power dissipation (60W), and transition frequency (10MHz) ratings. The TO-220-3 package geometry is identical, requiring no PCB layout modification.

Q: What is the primary reason for substituting BU408 with BU406G?

A: The BU408 is classified as obsolete, while the BU406G maintains active product status. This substitution ensures continued component availability and manufacturing support for production continuity.

Q: Are there packaging differences between BU408 and BU406G?

A: Both devices use TO-220-3 through-hole packages with identical pin configurations and mechanical dimensions. The BU406G is supplied in tube packaging, while the BU408 packaging format is not specified in available data. This difference does not affect circuit functionality or PCB mounting.

Q: Does BU406G meet the same regulatory requirements as BU408?

A: Yes. Both devices share identical REACH status (REACH Unaffected) and ECCN classification (EAR99). The BU406G additionally carries RoHS3 compliance certification, exceeding the regulatory profile of the obsolete BU408.

Q: What is the operating temperature range difference?

A: The BU408 operates to a maximum junction temperature of 150°C. The BU406G operates across −65°C to 150°C, providing extended low-temperature capability. Both devices share the same maximum operating temperature, ensuring thermal design compatibility.

Q: Are DC current gain specifications available for substitution verification?

A: DC current gain (hFE) minimum values are not provided in the available technical data for either device. Substitution decisions are based on the electrical parameters that are specified: collector current, breakdown voltage, power dissipation, and transition frequency.