BD677G Equivalent & Substitute Parts

Part Overview

The BD677G is an NPN Darlington bipolar junction transistor manufactured by onsemi, rated for 60 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 equivalent and substitute components for ongoing design support and procurement continuity. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts provide functional alternatives with modified parameters suitable for the same application categories.

Substiute Parts

BD677G

onsemiIn Stock: 34112BD677G Datasheet

Current PartRFQ

BD681G

onsemiIn Stock: 20339BD681G Datasheet

DirectRFQ

KSE800STU

Fairchild SemiconductorIn Stock: 1818KSE800STU Datasheet

DirectRFQ

BD677

STMicroelectronicsIn Stock: 1863BD677 Datasheet

DirectRFQ

BD677A

STMicroelectronicsIn Stock: 2487BD677A Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the BD677G is determined by electrical parameter compatibility within the NPN Darlington transistor category. The primary substitution criteria are:

Critical Parameters for Substitution:

• Transistor Type: NPN - Darlington configuration
• Maximum Collector Current (Ic): 4 A minimum
• Maximum Power Dissipation: 40 W minimum
• DC Current Gain (hFE): 750 minimum at specified conditions
• Operating Temperature Range: Support for -55°C to 150°C junction temperature
• Mounting Type: Through Hole configuration
• Package Compatibility: TO-126 or equivalent footprint

Substitution Categories:

Direct Equivalents maintain all electrical specifications and differ only in manufacturer or packaging format. These parts are pin-compatible and electrically interchangeable without circuit modification.

Voltage-Upgraded Substitutes provide higher collector-emitter breakdown voltage (100 V versus 60 V) while maintaining all other electrical parameters. These parts are suitable for applications where the original 60 V rating is marginal or where design margin improvement is beneficial.

Manufacturer Variants represent the same base product number from different semiconductor manufacturers, offering supply chain flexibility while preserving electrical and mechanical characteristics.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Obsolete to Active):

The BD681G (onsemi) serves as the primary substitute for the obsolete BD677G. This part maintains identical electrical specifications across all critical parameters including 4 A collector current, 40 W power rating, and DC current gain characteristics. The BD681G is classified as Active product status, ensuring long-term availability and supply chain continuity. The voltage rating increase from 60 V to 100 V provides additional design margin without affecting circuit operation in applications designed for 60 V operation. Both parts are ROHS3 compliant and REACH unaffected, meeting current regulatory requirements.

For Manufacturer Flexibility:

The BD677 from STMicroelectronics provides an alternative source for the base BD677 specification. This part maintains all electrical parameters of the original BD677G and is classified as Active. The primary difference is the supplier device package designation (SOT-32-3 versus TO-126), which represents the same physical through-hole footprint with identical pin configuration. ROHS3 compliance and REACH unaffected status align with regulatory requirements.

For Enhanced Performance:

The BD677A from STMicroelectronics represents an upgraded variant of the BD677 base product. This part maintains the 60 V voltage rating and 4 A current rating while offering modified saturation voltage characteristics (2.8V @ 40mA, 2A versus 2.5V @ 30mA, 1.5A). The DC current gain specification extends to 2A collector current, providing broader operational characterization. This part is suitable for applications requiring enhanced current handling at higher base drive levels. ROHS3 compliance and REACH unaffected status are maintained.

For Cross-Manufacturer Supply:

The KSE800STU from Fairchild Semiconductor provides a functionally equivalent NPN Darlington transistor with 60 V breakdown voltage and 4 A collector current rating. This part is classified as Active and offers supply diversification. The collector cutoff current specification (100µA) is lower than the BD677G specification (500µA), indicating superior leakage characteristics. The operating temperature specification lists only the maximum junction temperature (150°C) without the minimum temperature range. This part is suitable for applications where Fairchild device qualification is required or where supply chain redundancy is beneficial.

Frequently Asked Questions (FAQ)

Q: Can the BD681G directly replace the BD677G in existing designs?

A: Yes. The BD681G maintains all electrical specifications of the BD677G including 4 A collector current, 40 W power dissipation, and DC current gain characteristics. The increased voltage rating (100 V versus 60 V) does not affect operation in circuits designed for 60 V operation and provides additional design margin. Both parts use identical through-hole mounting and pin configuration.

Q: What is the difference between the BD677 and BD677A?

A: Both parts maintain the 60 V voltage rating and 4 A current rating. The BD677A specifies saturation voltage at higher base drive conditions (2.8V @ 40mA, 2A) compared to the BD677 (2.5V @ 30mA, 1.5A). The BD677A DC current gain specification extends to 2A collector current, providing characterization at higher current levels. Both parts are suitable for the same applications; the BD677A offers enhanced characterization for higher current operation.

Q: Are there package differences between substitute parts?

A: The BD677G, BD681G, and KSE800STU use TO-126 or TO-126-3 supplier device packages. The BD677 and BD677A use SOT-32-3 supplier device packages. All packages represent the same physical through-hole footprint with identical pin configuration and are mechanically interchangeable on printed circuit boards.

Q: Does the KSE800STU offer any advantages over the BD677G?

A: The KSE800STU provides cross-manufacturer supply flexibility and lower collector cutoff current (100µA versus 500µA), indicating superior leakage characteristics. This part is suitable for applications where Fairchild device qualification is required or where reduced leakage current is beneficial. The operating temperature specification differs, listing only the maximum junction temperature without the minimum range.

Q: Which substitute part should be selected for new designs?

A: The BD681G is recommended for new designs requiring direct replacement of the obsolete BD677G. This part is classified as Active, ensuring long-term availability, and maintains all electrical specifications while providing increased voltage margin. ROHS3 compliance and REACH unaffected status meet current regulatory requirements. The BD677A offers an alternative for applications requiring enhanced current characterization at higher base drive levels.

Q: Are all substitute parts RoHS compliant?

A: The BD677G, BD681G, BD677, and BD677A are all ROHS3 compliant. The KSE800STU RoHS compliance status is not specified in the provided data. Compliance verification with the component supplier is recommended for applications with strict RoHS requirements.

Q: Can the BD677 or BD677A be used interchangeably with the BD677G?

A: Yes. Both the BD677 and BD677A maintain the electrical specifications of the BD677G and are classified as Active. The primary difference is the supplier device package designation (SOT-32-3), which represents the same physical through-hole footprint. Both parts are suitable for direct replacement in existing designs.