BD680G PNP Darlington Transistor Equivalent & Substitute Parts

Part Overview

The BD680G is a PNP 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 component is classified as obsolete, necessitating identification of equivalent substitute parts for ongoing design support and procurement continuity. Substitute parts must maintain electrical and mechanical compatibility across critical performance parameters including voltage rating, current capacity, power dissipation, and thermal operating range.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP - Darlington	—
Current - Collector (Ic) Max	4	A
Voltage - Collector Emitter Breakdown (Max)	80	V
Power - Max	40	W
Operating Temperature Range	-55 to 150	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	TO-225AA, TO-126-3	—
DC Current Gain (hFE) Min	750	@ 1.5A, 3V
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution eligibility for the BD680G is determined by strict equivalence across the following parameters:

Primary Substitution Criteria:

Transistor Type: PNP - Darlington configuration
Maximum Collector Current (Ic): 4 A minimum
Collector-Emitter Breakdown Voltage: 80 V minimum
Maximum Power Dissipation: 40 W minimum
Operating Temperature Range: -55°C to 150°C minimum
Mounting Type: Through Hole
Package Compatibility: TO-126-3 or equivalent mechanical footprint

Secondary Compliance Criteria:

RoHS3 Compliance
REACH Unaffected status
Moisture Sensitivity Level: 1 (Unlimited) or equivalent

Parts meeting all primary criteria are classified as direct substitutes. Variations in secondary parameters such as Vce saturation voltage, collector cutoff current, or DC current gain do not disqualify substitution provided the part meets or exceeds the minimum electrical specifications.

Parameter Comparison

Parameter	BD680G (onsemi)	MJE702G (onsemi)	MJE703G (onsemi)	BD680 (STMicroelectronics)
Transistor Type	PNP - Darlington	PNP - Darlington	PNP - Darlington	PNP - Darlington
Current - Collector (Ic) Max	4 A	4 A	4 A	4 A
Voltage - Collector Emitter Breakdown (Max)	80 V	80 V	80 V	80 V
Power - Max	40 W	40 W	40 W	40 W
Operating Temperature Range	-55 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-225AA, TO-126-3	TO-225AA, TO-126-3	TO-225AA, TO-126-3	TO-225AA, TO-126-3
DC Current Gain (hFE) Min	750 @ 1.5A, 3V	750 @ 1.5A, 3V	750 @ 2A, 3V	750 @ 1.5A, 3V
Vce Saturation (Max)	2.5V @ 30mA, 1.5A	2.5V @ 30mA, 1.5A	2.8V @ 40mA, 2A	2.5V @ 30mA, 1.5A
Current - Collector Cutoff (Max)	500µA	100µA	100µA	500µA
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected
Product Status	Obsolete	Obsolete	Obsolete	Active

Engineering Selection Recommendations

BD680 (STMicroelectronics) is the primary recommended substitute for BD680G applications. This part maintains identical electrical specifications across all critical parameters and is classified as Active product status, ensuring long-term availability and supply chain continuity. The STMicroelectronics BD680 is supplied in SOT-32-3 package format, which is mechanically compatible with TO-126-3 footprints in through-hole applications. RoHS3 compliance and REACH Unaffected status align with the original BD680G specifications.

MJE702G (onsemi) qualifies as a direct electrical substitute, meeting all primary substitution criteria. This part exhibits improved collector cutoff current performance (100µA versus 500µA) and maintains identical Vce saturation characteristics. MJE702G is suitable for applications where lower leakage current is beneficial. Product status is Obsolete, consistent with the original part.

MJE703G (onsemi) qualifies as a direct electrical substitute with variations in saturation voltage characteristics. This part operates at higher collector current levels (2A versus 1.5A at saturation measurement) and exhibits slightly elevated Vce saturation (2.8V versus 2.5V). MJE703G is suitable for applications tolerant of higher saturation voltage. Product status is Obsolete.

Selection between substitute parts should prioritize the STMicroelectronics BD680 for new designs and long-term production due to Active product status. onsemi MJE702G and MJE703G are suitable for legacy system maintenance where original part sourcing is constrained.

Frequently Asked Questions (FAQ)

Q: Can MJE702G replace BD680G in all applications?

A: MJE702G meets all primary electrical and mechanical substitution criteria. The part maintains 4 A collector current, 80 V breakdown voltage, 40 W power rating, and TO-126-3 package compatibility. Improved collector cutoff current (100µA) does not degrade performance in standard switching applications. Substitution is valid across equivalent circuit topologies.

Q: What is the difference between MJE702G and MJE703G?

A: Both parts meet substitution criteria but differ in saturation characteristics. MJE702G exhibits Vce saturation of 2.5V at 1.5A collector current, while MJE703G exhibits 2.8V at 2A collector current. MJE703G operates at higher current levels during saturation measurement. Selection depends on circuit requirements for saturation voltage performance. Both parts maintain 750 minimum DC current gain.

Q: Why is BD680 (STMicroelectronics) recommended over onsemi alternatives?

A: BD680 from STMicroelectronics is classified as Active product status, ensuring continued manufacturing and supply availability. onsemi MJE702G and MJE703G are Obsolete, presenting potential long-term sourcing constraints. For new designs and production planning, the Active status BD680 provides superior supply chain reliability while maintaining identical electrical specifications.

Q: Are package differences between TO-126-3 and SOT-32-3 significant?

A: Both package designations refer to equivalent through-hole configurations with identical mechanical footprints and pin assignments. TO-126-3 and SOT-32-3 are interchangeable in PCB layouts. No design modifications are required for package substitution between these formats.

Q: Do all substitute parts comply with RoHS3 and REACH requirements?

A: All listed substitute parts (MJE702G, MJE703G, and BD680) are RoHS3 Compliant and REACH Unaffected, matching the original BD680G compliance status. No regulatory or environmental qualification changes are required for substitution.

Q: What is the significance of DC Current Gain (hFE) variations?

A: All substitute parts maintain minimum DC current gain of 750, meeting the original BD680G specification. Variations in measurement conditions (1.5A versus 2A collector current) do not affect practical circuit performance. Darlington configuration ensures sufficient current amplification across standard operating ranges.

Q: Can these parts be used in high-temperature applications?

A: All substitute parts maintain the -55°C to 150°C operating temperature range, supporting equivalent thermal performance. No derating is required for temperature-dependent applications within this range.

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