MJE18008 NPN Bipolar Transistor Equivalent & Substitute Parts

Part Overview

The MJE18008 is an NPN bipolar junction transistor manufactured by onsemi, rated for 450 V collector-emitter breakdown voltage and 8 A maximum collector current in a TO-220 through-hole package. This device is classified as obsolete, necessitating identification of functionally equivalent alternatives for new designs and production continuity. The MJE18008 operates within the SWITCHMODE™ series and is rated for 125 W maximum power dissipation with a transition frequency of 13 MHz, making it suitable for high-voltage switching applications.

Substiute Parts

MJE18008

onsemiIn Stock: 2282MJE18008 Datasheet

Current PartRFQ

MJE18008G

onsemiIn Stock: 8170MJE18008G Datasheet

DirectRFQ

BUJ105A,127

WeEn SemiconductorsIn Stock: 835BUJ105A,127 Datasheet

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ST13007

STMicroelectronicsIn Stock: 1296ST13007 Datasheet

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ST13007D

STMicroelectronicsIn Stock: 680301ST13007D Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the MJE18008 is determined by the following critical parameters: NPN transistor type, collector-emitter breakdown voltage rating, maximum collector current, maximum power dissipation, and through-hole TO-220 package compatibility. Substitute parts are grouped into two categories based on voltage rating alignment:

Direct Equivalent (450 V Rating): Parts maintaining the full 450 V breakdown voltage specification of the original MJE18008.

Functional Equivalent (400 V Rating): Parts with reduced breakdown voltage (400 V) but identical 8 A collector current and through-hole TO-220 packaging. These substitutes are suitable for applications where the operating voltage does not exceed 400 V.

The key differentiating parameters for substitution eligibility are:

• Collector-emitter breakdown voltage (450 V or 400 V)
• Maximum collector current (8 A)
• Package type (TO-220-3 through-hole)
• Transistor polarity (NPN)

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: MJE18008G is the direct equivalent replacement for the obsolete MJE18008. Both parts are manufactured by onsemi, share identical electrical specifications (450 V breakdown, 8 A collector current, 125 W power rating, 13 MHz transition frequency), and use the same TO-220-3 package. MJE18008G is currently in active production status with ROHS3 compliance, making it the preferred choice for design continuity and regulatory compliance.

Secondary Substitutes: ST13007, ST13007D, and BUJ105A,127 are functional equivalents suitable for applications where the operating voltage does not exceed 400 V. These parts maintain the 8 A collector current and TO-220-3 package compatibility but operate at reduced maximum power dissipation (80 W versus 125 W). All three secondary substitutes are in active production with current RoHS compliance certifications. Selection among these three should be based on availability, lead time, and cost considerations, as electrical performance differences are minimal within the 400 V voltage class.

Frequently Asked Questions (FAQ)

Q: Can MJE18008G directly replace MJE18008 in existing designs?

A: Yes. MJE18008G is electrically and mechanically identical to MJE18008, with the same 450 V breakdown voltage, 8 A collector current, 125 W power rating, and TO-220-3 package. The primary difference is product status (active versus obsolete) and RoHS compliance level.

Q: What is the voltage limitation when using ST13007, ST13007D, or BUJ105A,127 as substitutes?

A: These parts are rated for 400 V maximum collector-emitter breakdown voltage, compared to 450 V for the MJE18008. They are suitable only for applications where the operating voltage remains below 400 V. Exceeding this voltage rating will result in device failure.

Q: Are there differences in power dissipation between the MJE18008 and the 400 V alternatives?

A: Yes. The MJE18008 and MJE18008G are rated for 125 W maximum power dissipation, while ST13007, ST13007D, and BUJ105A,127 are rated for 80 W. Applications requiring power dissipation above 80 W must use MJE18008G or accept reduced thermal margin with the 400 V alternatives.

Q: Do all substitute parts use the same TO-220 package?

A: All substitute parts use the TO-220-3 through-hole package, ensuring mechanical compatibility with existing PCB layouts and thermal management solutions. BUJ105A,127 uses the TO-220AB variant, which is mechanically and electrically compatible with standard TO-220-3 footprints.

Q: What is the difference between ST13007 and ST13007D?

A: Both ST13007 and ST13007D are manufactured by STMicroelectronics with identical voltage (400 V) and current (8 A) ratings in TO-220-3 packages. The primary differences are in DC current gain specifications and saturation voltage characteristics. ST13007D exhibits higher current gain (8 @ 5A, 5V versus 5 @ 5A, 5V) and lower saturation voltage (2V @ 2A, 8A versus 3V @ 2A, 8A), making it suitable for applications requiring improved switching performance.

Q: Are all substitute parts RoHS compliant?

A: MJE18008G, ST13007, and ST13007D are ROHS3 compliant. BUJ105A,127 is RoHS compliant. The original MJE18008 is RoHS non-compliant. For applications requiring RoHS compliance, use MJE18008G or the STMicroelectronics alternatives.

Q: What is the transition frequency specification for the 400 V alternatives?

A: Transition frequency data is not provided for ST13007, ST13007D, or BUJ105A,127. The MJE18008 and MJE18008G are specified at 13 MHz. Applications with specific frequency requirements should verify transition frequency specifications with the manufacturer before substitution.