BD677 NPN Darlington Transistor Equivalent & Substitute Parts

Part Overview

The BD677 is an NPN Darlington bipolar junction transistor rated for 60 V collector-emitter breakdown voltage and 4 A maximum collector current. Designed for Through Hole mounting in TO-126 package configuration, this device delivers 40 W maximum power dissipation and operates across the temperature range of -55°C to 150°C junction temperature.

The original BD677 manufactured by onsemi is classified as Obsolete product status. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this Darlington transistor topology.

Substiute Parts

BD677

onsemiIn Stock: 1878BD677 Datasheet

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BD677

STMicroelectronicsIn Stock: 1863BD677 Datasheet

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BD677A

STMicroelectronicsIn Stock: 2487BD677A Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the BD677 is determined by strict equivalence across the following electrical and mechanical parameters:

Electrical Equivalence Criteria:

• Transistor Type: NPN - Darlington configuration
• Maximum Collector Current (Ic): 4 A
• Collector-Emitter Breakdown Voltage: 60 V
• Maximum Power Dissipation: 40 W
• DC Current Gain (hFE) Minimum: 750 or greater
• Collector Cutoff Current: 500 µA or less
• Operating Temperature Range: Minimum -55°C to 150°C junction temperature

Mechanical Equivalence Criteria:

• Mounting Type: Through Hole
• Package Classification: TO-225AA, TO-126-3 compatible footprints

The BD677 manufactured by STMicroelectronics and the BD677A variant meet these substitution criteria. Both devices maintain electrical parameter equivalence within specified tolerances and support identical Through Hole mounting applications. The STMicroelectronics BD677 transitions from Obsolete to Active product status, while BD677A provides an upgraded variant with enhanced specifications and Active product availability.

Parameter Comparison

Engineering Selection Recommendations

BD677 (STMicroelectronics): This part provides direct electrical and mechanical substitution for the obsolete onsemi BD677. The STMicroelectronics variant maintains identical electrical specifications while offering Active product status and ROHS3 compliance. Selection of this part eliminates obsolescence risk and satisfies modern regulatory requirements for new production builds and design refreshes.

BD677A (STMicroelectronics): This upgraded variant delivers equivalent electrical performance with enhanced Vce saturation characteristics at higher collector current levels (2.8V @ 40mA, 2A versus 2.5V @ 30mA, 1.5A). The BD677A maintains 4 A maximum collector current, 60 V breakdown voltage, and 40 W power rating. Active product status and ROHS3 compliance support long-term supply chain continuity. The BD677A is suitable for applications requiring improved saturation performance or where higher collector current operation is anticipated.

Both STMicroelectronics alternatives provide ROHS3 compliance and Active product status, addressing regulatory and availability concerns associated with the Obsolete onsemi BD677.

Frequently Asked Questions (FAQ)

Q: Can the BD677 (STMicroelectronics) be used as a direct replacement for the BD677 (onsemi)?

A: Yes. Both devices share identical electrical specifications including 4 A maximum collector current, 60 V breakdown voltage, 40 W power dissipation, and 750 minimum DC current gain. Through Hole mounting and TO-126 package compatibility enable direct PCB substitution. The STMicroelectronics variant provides Active product status versus Obsolete classification for the onsemi part.

Q: What is the difference between BD677 and BD677A?

A: The BD677A exhibits enhanced Vce saturation characteristics at higher collector current levels (2.8V @ 40mA, 2A) compared to the standard BD677 (2.5V @ 30mA, 1.5A). Both devices maintain identical maximum ratings of 4 A collector current, 60 V breakdown voltage, and 40 W power dissipation. The BD677A supports operation at higher collector current points while maintaining the same DC current gain minimum of 750.

Q: Are there package differences between these parts?

A: The onsemi BD677 is supplied in TO-126 package configuration. The STMicroelectronics BD677 and BD677A are supplied in SOT-32-3 package configuration. Both package types support TO-225AA and TO-126-3 footprint compatibility for Through Hole mounting applications. Verify PCB layout compatibility with the specific supplier device package before implementation.

Q: Do these parts meet current regulatory requirements?

A: The STMicroelectronics BD677 and BD677A are ROHS3 compliant and REACH unaffected. The onsemi BD677 is RoHS non-compliant. For applications subject to RoHS regulations or customer requirements mandating RoHS compliance, the STMicroelectronics variants are required.

Q: What is the operating temperature range for these devices?

A: The onsemi BD677 operates from -55°C to 150°C junction temperature. The STMicroelectronics BD677 and BD677A are specified to 150°C junction temperature maximum. Applications requiring operation below 0°C should verify compatibility with the STMicroelectronics variants, which do not specify a minimum operating temperature.

Q: Are moisture sensitivity considerations different between these parts?

A: All three variants carry Moisture Sensitivity Level (MSL) 1 classification, indicating unlimited shelf life without moisture control requirements. No differentiation exists in moisture handling or storage protocols across these parts.