MJE802G Equivalent & Substitute Parts

Part Overview

The MJE802G is an NPN Darlington bipolar junction transistor manufactured by onsemi, rated for 80 V collector-emitter breakdown voltage and 4 A maximum collector current in a TO-126 through-hole package. This device is classified as obsolete, necessitating identification of active equivalent and substitute components for ongoing design requirements and production continuity.

Substiute Parts

MJE802G

onsemiIn Stock: 25456MJE802G Datasheet

Current PartRFQ

BD681G

onsemiIn Stock: 20339BD681G Datasheet

DirectRFQ

BD679AS

onsemiIn Stock: 1998BD679AS Datasheet

SimilarRFQ

BD679

STMicroelectronicsIn Stock: 23392BD679 Datasheet

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BD679A

STMicroelectronicsIn Stock: 1566BD679A Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the MJE802G is determined by the following critical parameters: transistor type (NPN Darlington), maximum collector current (4 A), maximum collector-emitter breakdown voltage (80 V or higher), maximum power dissipation (40 W), DC current gain minimum (750), operating temperature range (-55°C to 150°C), and through-hole mounting configuration.

Substitute parts are grouped into two categories:

Direct Voltage Rating Match (80 V): Parts maintaining the original 80 V breakdown voltage specification with identical or superior electrical characteristics and active product status.

Elevated Voltage Rating (100 V): Parts with higher collector-emitter breakdown voltage, providing enhanced voltage margin while maintaining all other critical parameters at or above the original specification.

All substitute parts maintain NPN Darlington configuration, 4 A collector current rating, 40 W power dissipation, and through-hole mounting. Variations in package designation (TO-126 versus TO-126-3 versus SOT-32-3) and manufacturer (onsemi versus STMicroelectronics) are noted for mechanical and sourcing considerations.

Parameter Comparison

Engineering Selection Recommendations

BD681G (onsemi): This part is the primary direct substitute for the MJE802G. It maintains onsemi manufacturer continuity, identical collector current and power ratings, and active product status. The elevated 100 V breakdown voltage provides additional voltage margin over the original 80 V specification. Operating temperature range extends to 150°C maximum junction temperature. Package designation TO-126 matches the original mechanical footprint. ROHS3 compliance and REACH unaffected status align with regulatory requirements.

BD679AS (onsemi): This part provides an alternative within the onsemi product line with matching 80 V breakdown voltage and 4 A collector current. Active product status and ROHS3 compliance are confirmed. Package designation TO-126-3 represents a variant of the original TO-126 footprint. Operating temperature specification is limited to 150°C maximum junction temperature without lower temperature bound documentation.

BD679 (STMicroelectronics): This part offers cross-manufacturer substitution with matching electrical specifications (80 V, 4 A, 40 W). Active product status and ROHS3 compliance are confirmed. Package designation SOT-32-3 differs from the original TO-126, requiring mechanical verification for board-level compatibility. Moisture sensitivity level 1 (unlimited) matches the original specification. Inventory availability is substantial at 23,300 pieces.

BD679A (STMicroelectronics): This part provides an alternative STMicroelectronics option with identical electrical ratings to BD679. Active product status and ROHS3 compliance are confirmed. Package designation SOT-32-3 requires mechanical compatibility assessment. Moisture sensitivity level 1 (unlimited) is maintained.

Frequently Asked Questions (FAQ)

Q: Can BD681G be used as a direct replacement for MJE802G in all applications?

A: BD681G is electrically compatible with MJE802G for applications operating at or below 80 V. The elevated 100 V breakdown voltage of BD681G provides additional voltage margin and does not degrade performance in circuits designed for 80 V operation. Package compatibility (TO-126) is confirmed. Verification of board-level mechanical fit is required.

Q: What is the primary difference between BD679AS and BD679?

A: BD679AS is manufactured by onsemi with TO-126-3 package designation, while BD679 is manufactured by STMicroelectronics with SOT-32-3 package designation. Both maintain 80 V breakdown voltage and 4 A collector current ratings. The package difference requires mechanical compatibility assessment for PCB mounting.

Q: Are there operating temperature differences between MJE802G and the substitute parts?

A: MJE802G specifies -55°C to 150°C operating temperature range. BD681G maintains this full range. BD679AS, BD679, and BD679A specify 150°C maximum junction temperature without documented lower temperature limits. Applications requiring operation below 0°C should prioritize BD681G or verify substitute part low-temperature performance requirements.

Q: Can SOT-32-3 packaged parts (BD679, BD679A) be used on boards designed for TO-126 footprints?

A: SOT-32-3 and TO-126 are distinct package types with different mechanical dimensions and pin configurations. Direct PCB footprint substitution is not possible without board redesign. Mechanical compatibility must be verified before implementation.

Q: What is the significance of the higher collector cutoff current in substitute parts?

A: BD681G, BD679AS, BD679, and BD679A specify 500µA maximum collector cutoff current, compared to 100µA for MJE802G. This parameter affects leakage current behavior in off-state conditions. For applications sensitive to leakage current, circuit-level performance validation is required.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. BD681G, BD679AS, BD679, and BD679A are all ROHS3 compliant and REACH unaffected, matching the regulatory status of MJE802G.