BD159G Equivalent & Substitute Parts

Part Overview

The BD159G is an NPN bipolar junction transistor manufactured by onsemi, rated for 350 V collector-emitter breakdown voltage and 500 mA maximum collector current in a 20 W Through Hole TO-126 package. The device is classified as obsolete, necessitating identification of active equivalent parts for ongoing design requirements and procurement needs. Substitute parts must maintain functional compatibility within the electrical and mechanical constraints of the original specification.

Substiute Parts

BD159G

onsemiIn Stock: 929BD159G Datasheet

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KSC3503DS

onsemiIn Stock: 5952KSC3503DS Datasheet

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KSC3503DSTU

onsemiIn Stock: 736KSC3503DSTU Datasheet

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MJE340G

onsemiIn Stock: 6945MJE340G Datasheet

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MJE340

NTE Electronics, IncIn Stock: 2035MJE340 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the BD159G is determined by the following critical parameters: transistor type (NPN), collector-emitter breakdown voltage rating, maximum collector current, power dissipation capability, DC current gain, operating temperature range, and through-hole mounting compatibility. Substitute parts are grouped based on whether they meet or exceed the electrical requirements of the original specification while maintaining package compatibility.

Critical Substitution Parameters:

• Transistor Type: NPN
• Voltage - Collector Emitter Breakdown (Max): ≥ 350 V
• Current - Collector (Ic) (Max): ≥ 500 mA
• Power - Max: ≥ 20 W
• Mounting Type: Through Hole
• Package Compatibility: TO-126 or TO-126-3

Parameter Comparison

Engineering Selection Recommendations

Primary Substitutes (Full Electrical Compatibility):

MJE340G and MJE340 are direct electrical equivalents to the BD159G. Both parts maintain the 500 mA collector current rating and 20 W power dissipation capability. MJE340G (onsemi, ROHS3 Compliant) is the preferred substitute due to active product status and full regulatory compliance. MJE340 (NTE Electronics, Inc) provides equivalent electrical performance but carries RoHS non-compliant status and lacks specified operating temperature range documentation.

Secondary Substitutes (Reduced Current and Power Rating):

KSC3503DS and KSC3503DSTU are active NPN transistors with reduced electrical ratings. Both parts are limited to 100 mA maximum collector current and 7 W power dissipation, representing a 5-fold reduction in current handling and 65% reduction in power capability compared to the BD159G. These parts are suitable only for applications where the original 500 mA and 20 W specifications exceed actual circuit requirements. Both KSC3503 variants maintain ROHS3 compliance and active product status.

Compliance Considerations:

All recommended substitutes (MJE340G, KSC3503DS, KSC3503DSTU) maintain ROHS3 compliance and active product status. The MJE340 variant from NTE Electronics, Inc does not meet current RoHS requirements and should be avoided in new designs subject to environmental compliance mandates.

Frequently Asked Questions (FAQ)

Q: Can KSC3503DS or KSC3503DSTU replace BD159G in all applications?

A: No. The KSC3503 series is limited to 100 mA collector current and 7 W power dissipation, compared to the BD159G specification of 500 mA and 20 W. These parts are suitable only for circuits where actual operating current and power requirements are within the KSC3503 ratings. Applications requiring the full 500 mA or 20 W capability must use MJE340G or MJE340.

Q: What is the difference between MJE340G and MJE340?

A: Both parts provide identical electrical specifications (500 mA, 20 W, 300 V). The primary differences are manufacturer (onsemi versus NTE Electronics, Inc) and regulatory compliance. MJE340G is ROHS3 compliant with active product status. MJE340 is RoHS non-compliant and lacks documented operating temperature range. MJE340G is the preferred choice for new designs.

Q: Why does the BD159G have a 350 V rating while MJE340G is rated at 300 V?

A: The BD159G collector-emitter breakdown voltage is 350 V, while MJE340G is rated at 300 V. In applications where the circuit operates below 300 V, this difference is not functionally significant. For circuits requiring operation above 300 V, the reduced voltage rating of MJE340G may present a limitation.

Q: Are the KSC3503DS and KSC3503DSTU parts interchangeable with each other?

A: Both parts share identical electrical specifications except for DC current gain minimum values (60 @ 10mA, 10V for KSC3503DS versus 40 @ 10mA, 10V for KSC3503DSTU). The primary difference is packaging: KSC3503DS is supplied in Bulk, while KSC3503DSTU is supplied in Tube. Electrical performance is equivalent for most applications.

Q: What is the operating temperature range difference between BD159G and substitute parts?

A: BD159G and MJE340G both specify -65°C to 150°C operating temperature range. KSC3503DS and KSC3503DSTU specify -55°C to 150°C, representing a 10°C reduction in minimum operating temperature. For applications requiring operation below -55°C, MJE340G is the appropriate substitute.

Q: Are all substitute parts available in the same TO-126 package?

A: All substitute parts are available in TO-126 or TO-126-3 package configurations, maintaining mechanical compatibility with the original BD159G. Package designation variations (TO-126 versus TO-126-3) represent supplier device package nomenclature and do not affect physical form factor or pin compatibility.