MJE802 Equivalent & Substitute Parts

Part Overview

The MJE802 is a Bipolar (BJT) Transistor NPN - Darlington configuration rated for 80 V collector-emitter breakdown voltage and 4 A maximum collector current with 40 W power dissipation capability. The device is packaged in Through Hole SOT-32 configuration and is classified as Obsolete product status. Due to obsolescence, equivalent substitute parts with matching electrical and mechanical specifications are required for design continuity and procurement purposes.

Key Parameters

Parameter	Value
Transistor Type	NPN - Darlington
Current - Collector (Ic) (Max)	4 A
Voltage - Collector Emitter Breakdown (Max)	80 V
Power - Max	40 W
DC Current Gain (hFE) (Min)	750 @ 1.5A, 3V
Operating Temperature (TJ)	150°C
Mounting Type	Through Hole
Package / Case	TO-225AA, TO-126-3
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the MJE802 are qualified based on the following electrical and mechanical parameters:

Electrical Matching Criteria:

Transistor Type: NPN - Darlington configuration
Maximum Collector Current (Ic): 4 A
Maximum Collector-Emitter Breakdown Voltage: 80 V
Maximum Power Dissipation: 40 W
DC Current Gain (hFE): Minimum 750 @ specified conditions
Operating Temperature Range: 150°C (TJ)

Mechanical Matching Criteria:

Mounting Type: Through Hole
Package / Case: TO-225AA or TO-126-3
RoHS Compliance: ROHS3 Compliant

The substitute parts BD679 (STMicroelectronics) and BD679AS (onsemi) satisfy all electrical and mechanical requirements for direct substitution with the MJE802. Both parts maintain identical voltage and current ratings, power dissipation capability, and thermal operating range. Package compatibility is confirmed through TO-225AA and TO-126-3 case designations.

Parameter Comparison

Parameter	MJE802	BD679	BD679AS
Manufacturer	STMicroelectronics	STMicroelectronics	onsemi
Transistor Type	NPN - Darlington	NPN - Darlington	NPN - Darlington
Current - Collector (Ic) (Max)	4 A	4 A	4 A
Voltage - Collector Emitter Breakdown (Max)	80 V	80 V	80 V
Power - Max	40 W	40 W	40 W
DC Current Gain (hFE) (Min)	750 @ 1.5A, 3V	750 @ 1.5A, 3V	750 @ 2A, 3V
Operating Temperature (TJ)	150°C	150°C	150°C
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	TO-225AA, TO-126-3	TO-225AA, TO-126-3	TO-225AA, TO-126-3
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected
Product Status	Obsolete	Active	Active

Engineering Selection Recommendations

BD679 (STMicroelectronics) is the primary substitute for the MJE802. This part maintains Active product status with 23,300 units in stock inventory, ensuring long-term availability. The BD679 is supplied in SOT-32-3 package configuration and carries identical electrical specifications including 4 A collector current, 80 V breakdown voltage, and 40 W power rating. ROHS3 compliance and REACH Unaffected status align with the original MJE802 specifications.

BD679AS (onsemi) serves as an alternative substitute with Active product status and 1,956 units in stock. This part is supplied in TO-126-3 package configuration and meets all electrical requirements. The BD679AS carries ROHS3 compliance and REACH Unaffected status. The onsemi sourcing option provides supply chain diversification while maintaining full electrical and thermal compatibility.

Both substitute parts eliminate obsolescence risk associated with the MJE802 while preserving circuit performance through matched electrical characteristics and thermal operating range.

Frequently Asked Questions (FAQ)

Q: Can BD679 and BD679AS be used interchangeably with MJE802?

A: Both BD679 and BD679AS meet all electrical and mechanical specifications for direct substitution with MJE802. The primary difference is package configuration: BD679 uses SOT-32-3 while BD679AS uses TO-126-3. Both package types are compatible with TO-225AA and TO-126-3 case designations. Selection depends on PCB layout requirements and available footprint compatibility.

Q: What are the key electrical parameters that determine substitution compatibility?

A: Substitution compatibility is determined by: Transistor Type (NPN - Darlington), Maximum Collector Current (4 A), Maximum Collector-Emitter Breakdown Voltage (80 V), Maximum Power Dissipation (40 W), DC Current Gain (750 minimum), and Operating Temperature Range (150°C TJ). All substitute parts match these specifications.

Q: Why is the MJE802 classified as Obsolete?

A: The MJE802 is listed as Obsolete product status. BD679 and BD679AS are Active products with significantly higher inventory availability (23,300 and 1,956 units respectively versus 1,920 units for MJE802), ensuring reliable long-term procurement and supply chain continuity.

Q: Are there compliance differences between MJE802 and the substitute parts?

A: All three parts carry identical compliance certifications: ROHS3 Compliant and REACH Unaffected status. No compliance compromises result from substitution.

Q: What is the difference between BD679 and BD679AS?

A: Both parts are electrically identical NPN - Darlington transistors with 4 A, 80 V, and 40 W ratings. The primary differences are manufacturer (STMicroelectronics versus onsemi) and package configuration (SOT-32-3 versus TO-126-3). BD679 offers higher inventory availability while BD679AS provides alternative sourcing from a different manufacturer.

Q: Can package configuration affect circuit performance?

A: Package configuration affects PCB layout and thermal management implementation but does not alter electrical performance. Both SOT-32-3 and TO-126-3 packages support the same electrical specifications and thermal operating range. Package selection is determined by PCB footprint requirements and thermal dissipation design.

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