BUL49D Equivalent & Substitute Parts

Part Overview

The BUL49D is an NPN bipolar junction transistor manufactured by STMicroelectronics, rated for 450 V collector-emitter breakdown voltage and 5 A maximum collector current. This device is packaged in TO-220-3 through-hole configuration and is designed for high-voltage switching applications requiring 80 W power dissipation capability. The BUL49D maintains Active product status with full RoHS3 compliance and unlimited moisture sensitivity rating.

Substitute parts are necessary when the primary device becomes unavailable due to supply constraints, manufacturing discontinuation, or when alternative manufacturers' components meet identical electrical and mechanical specifications within the allowed parameter ranges.

Substiute Parts

BUL49D

STMicroelectronicsIn Stock: 6249BUL49D Datasheet

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BUT11A

STMicroelectronicsIn Stock: 2451BUT11A Datasheet

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FJP5555TU

Fairchild SemiconductorIn Stock: 6178FJP5555TU Datasheet

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KSC5338D

onsemiIn Stock: 2042KSC5338D Datasheet

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KSC5338DTU

onsemiIn Stock: 2349KSC5338DTU Datasheet

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MJE18004G

onsemiIn Stock: 1405MJE18004G Datasheet

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MJE18008G

onsemiIn Stock: 8170MJE18008G Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the BUL49D is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

• Transistor Type: NPN (mandatory match)
• Voltage - Collector Emitter Breakdown (Max): 450 V (minimum requirement)
• Current - Collector (Ic) (Max): 5 A (minimum requirement)
• Mounting Type: Through Hole (mandatory match)
• Package / Case: TO-220-3 (mandatory match)
• Operating Temperature (Max): 150°C (mandatory match)

Secondary Compliance Criteria:

• RoHS3 Compliance (required for equivalent substitution)
• REACH Unaffected status (required for equivalent substitution)

Substitute parts are grouped into two categories: Direct Equivalents (matching all primary criteria with Active or Last Time Buy status) and Functional Alternatives (matching all primary criteria but with Obsolete status or higher power ratings).

Parameter Comparison

Engineering Selection Recommendations

Direct Equivalents (Recommended for Primary Selection):

The following parts satisfy all mandatory electrical and mechanical parameters while maintaining Active product status and full compliance certifications:

• KSC5338D (onsemi): Matches all primary criteria with Active status, RoHS3 compliance, and REACH Unaffected designation. Suitable for direct substitution in new designs and production environments.

• MJE18004G (onsemi): Matches all primary criteria with Active status, RoHS3 compliance, and REACH Unaffected designation. Belongs to SWITCHMODE™ series with extended operating temperature range (-65°C to 150°C).

• FJP5555TU (Fairchild Semiconductor): Matches all primary criteria with Active status. Note: Voltage rating is 400 V, which is below the 450 V specification of BUL49D. This part is suitable only for applications with maximum operating voltage of 400 V or lower.

Functional Alternatives (Secondary Selection):

• KSC5338DTU (onsemi): Matches all primary criteria but carries Last Time Buy status. Suitable for applications where supply continuity is not critical. RoHS3 compliant and REACH Unaffected.

• MJE18008G (onsemi): Exceeds primary current specification at 8 A maximum collector current and provides 125 W power dissipation. Suitable for applications requiring higher current capacity within the same voltage class. Active status with full compliance certifications.

Not Recommended:

• BUT11A (STMicroelectronics): Obsolete product status. Use only when no alternative is available and supply is confirmed.

Frequently Asked Questions (FAQ)

Q: Can FJP5555TU be used as a direct replacement for BUL49D?

A: FJP5555TU meets all mechanical and most electrical parameters but has a maximum collector-emitter breakdown voltage of 400 V compared to BUL49D's 450 V rating. It is suitable only for applications with maximum operating voltage of 400 V or lower. For applications requiring the full 450 V rating, use KSC5338D, KSC5338DTU, MJE18004G, or MJE18008G.

Q: What is the difference between KSC5338D and KSC5338DTU?

A: Both parts are electrically identical with matching electrical specifications. The primary difference is packaging: KSC5338D is supplied in Bulk packaging, while KSC5338DTU is supplied in Tube packaging. KSC5338DTU carries Last Time Buy status, indicating limited future availability. For new production, KSC5338D is preferred.

Q: Is MJE18008G a suitable substitute despite its higher current rating?

A: Yes. MJE18008G exceeds the minimum current requirement (8 A versus 5 A) and provides higher power dissipation (125 W versus 80 W). It maintains the same voltage rating (450 V), package type (TO-220-3), and operating temperature range. Higher current and power ratings do not prevent substitution in applications requiring 5 A or less.

Q: Why is BUT11A listed as a substitute if it is Obsolete?

A: BUT11A is included in the substitute list due to matching electrical and mechanical specifications. However, its Obsolete product status makes it unsuitable for new designs or long-term production. It should be used only when no Active or Last Time Buy alternatives are available and supply is confirmed through inventory verification.

Q: Are all substitute parts RoHS3 compliant?

A: KSC5338D, KSC5338DTU, MJE18004G, and MJE18008G are confirmed RoHS3 compliant. BUT11A is RoHS3 compliant. FJP5555TU compliance status is not specified in the provided data. Verify FJP5555TU RoHS3 compliance with the manufacturer before use in applications requiring regulatory compliance.

Q: Can these parts be used interchangeably in existing PCB designs?

A: Yes. All substitute parts use identical TO-220-3 through-hole packaging with the same pin configuration and mechanical footprint. No PCB layout modifications are required for substitution.

Q: What is the significance of the SWITCHMODE™ series designation for MJE18004G and MJE18008G?

A: SWITCHMODE™ is an onsemi product series designation indicating optimization for switching applications. These parts feature transition frequencies of 13 MHz, supporting high-frequency switching operation. This designation does not affect substitution eligibility but indicates suitability for high-speed switching circuits.