BD439S Equivalent & Substitute Parts

Part Overview

The BD439S is an NPN bipolar junction transistor manufactured by onsemi, rated for 60V collector-emitter breakdown voltage and 4A maximum collector current. This device is packaged in TO-126-3 through-hole configuration and delivers 36W maximum power dissipation with a 3MHz transition frequency. The BD439S is classified as obsolete, making identification of suitable substitute components necessary for ongoing design support and production continuity. Equivalent parts must maintain electrical and mechanical compatibility across critical performance parameters including voltage ratings, current capacity, and thermal characteristics.

Substiute Parts

BD439S

onsemiIn Stock: 2503BD439S Datasheet

Current PartRFQ

BD439G

onsemiIn Stock: 1784BD439G Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BD439S is determined by equivalence across the following critical parameters:

Electrical Compatibility Requirements:

• Transistor type must be NPN
• Voltage - Collector Emitter Breakdown rating must equal or exceed 60V
• Current - Collector (Ic) maximum rating must equal or exceed 4A
• Power dissipation capability must equal or exceed 36W
• Frequency - Transition must equal or exceed 3MHz

Mechanical Compatibility Requirements:

• Mounting type must be Through Hole
• Package / Case must be compatible with TO-126-3 footprint

Regulatory Compliance Requirements:

• RoHS3 compliance status must be maintained
• REACH status must remain unaffected

The BD439G meets all substitution criteria and is classified as an active product, providing long-term availability and design continuity.

Parameter Comparison

Engineering Selection Recommendations

The BD439G is the direct substitute for the BD439S. Both devices share identical electrical ratings across voltage, current, power, and frequency parameters. The BD439G maintains full RoHS3 compliance and REACH unaffected status, ensuring regulatory continuity.

The primary distinction between these parts is product status: the BD439S is obsolete while the BD439G is active. This status difference provides significant advantages for new designs and ongoing production. The BD439G offers extended availability, consistent supply chain access, and manufacturer support for technical documentation and process improvements.

Both parts are manufactured by onsemi and utilize the same TO-126-3 through-hole package, ensuring mechanical and thermal compatibility in existing PCB layouts without design modification.

Frequently Asked Questions (FAQ)

Q: Can the BD439G directly replace the BD439S in existing designs?

A: Yes. The BD439G provides direct electrical and mechanical substitution. Both devices share identical voltage ratings (60V), current capacity (4A), power dissipation (36W), and transition frequency (3MHz). The TO-126-3 package footprint is identical, requiring no PCB layout changes.

Q: What is the primary reason to transition from BD439S to BD439G?

A: The BD439S is classified as obsolete, while the BD439G is an active product. Transitioning to the BD439G ensures long-term component availability, consistent manufacturing processes, and ongoing manufacturer support.

Q: Are there any differences in DC current gain (hFE) between these parts?

A: The DC current gain specifications differ at different test conditions. The BD439S specifies hFE minimum of 20 @ 10mA, 5V, while the BD439G specifies hFE minimum of 40 @ 500mA, 1V. These measurements occur at different operating points and do not affect substitution compatibility for applications designed to the BD439S specifications.

Q: Do both parts meet the same regulatory requirements?

A: Yes. Both the BD439S and BD439G are ROHS3 compliant and REACH unaffected, maintaining identical regulatory status for applications requiring these certifications.

Q: Is the TO-126-3 package identical between both parts?

A: Yes. Both devices use the TO-126-3 through-hole package with identical mechanical dimensions and pin configuration, enabling direct PCB compatibility without layout modifications.

Q: What is the operating temperature range for each part?

A: The BD439S specifies a maximum operating temperature of 150°C. The BD439G specifies an operating temperature range of -55°C to 150°C, providing extended low-temperature capability while maintaining the same maximum rating.