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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi BD680

Name: BD680
Brand: onsemi
SKU: BD680
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BD680

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-225AA, TO-126-3

Datasheet:: BD680.pdf

Description:: TRANS PNP DARL 80V 4A TO-126

Quantity:: RFQ Add To RFQ list

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Inventory:2,309

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Product details

Overview

BD680 from onsemi is a plastic medium-power silicon PNP Darlington transistor designed for high-current switching and linear amplification in complementary output stages. It features 80 V_CEO, 4.0 A collector current, 40 W power dissipation at T_C = 25 °C, DC current gain ≥750 (IC = 1.5 A), and TO-225 package with emitter-base-collector pinout. It is used as an output device in general-purpose audio and power amplifier circuits.

For engineers reviewing the BD680 datasheet, pinout, applications, or equivalent options, key selection considerations include its 80 V breakdown rating, Darlington saturation voltage of 2.5 V (IC = 1.5 A, IB = 30 mA), thermal resistance of 3.13 °C/W, and RoHS-compliant Pb-free packaging - all critical for reliable high-current switching in industrial and consumer power stages.

Technical Context

The BD680 is a monolithic PNP Darlington pair with integrated base-emitter resistor network absent - requiring external base drive control. Its high h_FE enables low base current drive while maintaining robust secondary breakdown immunity up to 100 V and 4 A under defined SOA conditions.

It operates across −55 °C to +150 °C junction temperature range and exhibits V_CE(sat) ≤2.5 V and V_BE(on) ≈2.5 V at rated current, confirming its suitability for linear and saturated-mode operation in complementary symmetry amplifier outputs and relay drivers.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	80 Vdc - Maximum collector-emitter voltage before breakdown; defines safe operating voltage headroom in 48–72 V supply rails.
I_C	4.0 Adc - Continuous collector current capability; supports load switching up to ~30 W into 8 Ω loads with adequate heatsinking.
P_D @ T_C = 25 °C	40 W - Total device power dissipation limit at case temperature 25 °C; derates 0.32 W/°C above that point.
h_FE	≥750 @ I_C = 1.5 A, V_CE = 3 V - High DC current gain reduces required base drive current to ≤2 mA for full conduction.
V_CE(sat)	≤2.5 V @ I_C = 1.5 A, I_B = 30 mA - Low saturation voltage minimizes conduction loss and heat generation in switching applications.
R_JC	3.13 °C/W - Junction-to-case thermal resistance; determines minimum heatsink requirement for sustained 4 A operation.

Pinout & Package

BD680 is housed in a TO-225 package (Case 77-09, Style 1) with three leads and metal tab connected to collector. Pin 1 is emitter, pins 2 and 4 are collector (dual internal connection), and pin 3 is base. The package is Pb-free and RoHS compliant.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Emitter	Main current exit path; referenced to ground or negative rail in PNP configuration; electrically isolated from tab.
Pins 2 & 4	Collector	Primary current input node; internally bonded to metal tab for thermal conduction; must be electrically tied to heatsink ground plane.
Pin 3	Base	Control terminal for Darlington pair; requires ~30 mA drive for full saturation; no integrated base resistor.

Key Features

Feature	Design Value
High DC current gain	h_FE ≥750 enables microcontroller-level base drive (e.g., 3.3 V GPIO with 1 kΩ resistor) to switch 4 A loads.
Monolithic Darlington construction	Single-die integration ensures matched transistor characteristics and stable gain over temperature vs. discrete pairs.
Complementary pairing	BD680G/BD680AG are direct complements to NPN BD679/BD679A, enabling push-pull amplifier output stages without gain mismatch.
Pb-Free & RoHS compliant	Meets global environmental compliance requirements; compatible with lead-free reflow profiles and industrial assembly standards.

Applications

Audio Power Amplifier Output Stage	DC Motor Driver (Unidirectional)
Use Scenario: Driving 8 Ω speaker loads in Class AB amplifier output stage with ±40 V rails. IC Role / Device Role / Timing Role: PNP Darlington output transistor delivering peak current >3 A during signal peaks. Use Value: High h_FE and 80 V rating allow clean clipping margin and low crossover distortion when paired with BD679.	Use Scenario: Controlling 24 V, 3 A brushed DC motor in industrial actuator using single-ended switch topology. IC Role / Device Role / Timing Role: High-current PNP switch turning motor on/off via microcontroller-driven base resistor network. Use Value: 2.5 V V_CE(sat) limits conduction loss to <1.5 W at 3 A, reducing heatsink size versus standard PNP transistors.
Relay Driver Circuit	Linear Voltage Regulator Pass Element
Use Scenario: Driving 12 V, 200 mA coil relay from 3.3 V MCU GPIO through level-shifting resistor network. IC Role / Device Role / Timing Role: High-gain Darlington providing isolation and current amplification between logic and inductive load. Use Value: 750× current gain allows 270 μA base current to fully saturate - achievable with 12 kΩ pull-up resistor from 3.3 V.	Use Scenario: Acting as series pass element in adjustable 5–30 V, 2 A linear regulator with external error amplifier. IC Role / Device Role / Timing Role: High-power PNP pass transistor dissipating up to 35 W during worst-case dropout conditions. Use Value: 40 W rating and 3.13 °C/W R_JC support stable operation with moderate heatsinking at full 2 A load.

Audio Power Amplifier Output Stage

DC Motor Driver (Unidirectional)

Use Scenario: Driving 8 Ω speaker loads in Class AB amplifier output stage with ±40 V rails.

IC Role / Device Role / Timing Role: PNP Darlington output transistor delivering peak current >3 A during signal peaks.

Use Value: High h_FE and 80 V rating allow clean clipping margin and low crossover distortion when paired with BD679.

Use Scenario: Controlling 24 V, 3 A brushed DC motor in industrial actuator using single-ended switch topology.

IC Role / Device Role / Timing Role: High-current PNP switch turning motor on/off via microcontroller-driven base resistor network.

Use Value: 2.5 V V_CE(sat) limits conduction loss to <1.5 W at 3 A, reducing heatsink size versus standard PNP transistors.

Relay Driver Circuit

Linear Voltage Regulator Pass Element

Use Scenario: Driving 12 V, 200 mA coil relay from 3.3 V MCU GPIO through level-shifting resistor network.

IC Role / Device Role / Timing Role: High-gain Darlington providing isolation and current amplification between logic and inductive load.

Use Value: 750× current gain allows 270 μA base current to fully saturate - achievable with 12 kΩ pull-up resistor from 3.3 V.

Use Scenario: Acting as series pass element in adjustable 5–30 V, 2 A linear regulator with external error amplifier.

IC Role / Device Role / Timing Role: High-power PNP pass transistor dissipating up to 35 W during worst-case dropout conditions.

Use Value: 40 W rating and 3.13 °C/W R_JC support stable operation with moderate heatsinking at full 2 A load.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP Darlington transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJE702	Identical V_CEO = 80 V, I_C = 4 A, h_FE ≥750, TO-225 package; same pinout (E-C-B); datasheet confirms equivalence per onsemi BD680 datasheet footnote.	Same linear and switching use cases; widely available in legacy inventory; identical SOA curves and thermal specs.	Select MJE702 when sourcing from distributors carrying legacy ON Semiconductor or STMicroelectronics stock.
BD680AG	Same die and package as BD680G but specified for higher h_FE test condition (I_C = 2.0 A vs. 1.5 A); otherwise identical max ratings, pinout, and thermal performance.	No functional difference in circuit design; BD680AG guarantees ≥750 h_FE at higher current, offering margin for aging or elevated temperature operation.	Prefer BD680AG for new designs where long-term h_FE stability under sustained 2 A load is critical.

Compared with MJE702 and BD680AG, the BD680G offers identical electrical and mechanical specifications but is designated for standard-grade h_FE validation at 1.5 A - making it optimal for cost-sensitive, high-volume applications where guaranteed high-current gain margin is not required.

Availability

BD680 is available at Aetrix Electronics and suitable for audio amplifier output stages, DC motor drivers, relay interface circuits, and linear regulator pass elements requiring stable component supply and industrial-grade reliability.

Supply support for BD680 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BD680 belongs to onsemi's plastic medium-power PNP Darlington family, engineered for complementary output stage design in general-purpose amplifiers and robust high-current switching - emphasizing manufacturability, thermal reliability, and cross-platform compatibility.

FAQ

What is the maximum collector-emitter voltage rating for BD680?

The BD680 has a maximum collector-emitter voltage (V_CEO) rating of 80 Vdc, verified per onsemi's BD676/D datasheet Rev. 15. This rating applies to BD680G and BD680AG variants and defines the absolute maximum voltage the device can withstand in open-circuit or active mode before breakdown. Exceeding this voltage risks irreversible damage even under brief transient conditions.

Does BD680 include an integrated base resistor?

No, the BD680 does not include an integrated base resistor. It is a bare Darlington transistor requiring external base drive circuitry - such as a current-limiting resistor or active driver - to control conduction. This distinguishes it from "digital transistors" like the NSD series and allows precise optimization of switching speed and saturation depth in the BD680 application.

What is the thermal resistance junction-to-case for BD680?

The BD680 has a thermal resistance of R_JC = 3.13 °C/W, measured from junction to case surface (metal tab). This value is specified in the Thermal Characteristics table of the official onsemi BD676/D datasheet and directly informs heatsink sizing - for example, sustaining 4 A at 2.5 V V_CE(sat) generates ~10 W, requiring ≤12 °C/W total system thermal resistance to hold T_J ≤125 °C.

Is BD680 pin-compatible with BD679 or other complementary NPN devices?

BD680 is electrically complementary to BD679 and BD679A (NPN counterparts), but not pin-compatible - BD680 uses E-C-B pinout (TO-225 Style 1), whereas BD679 uses C-B-E. PCB layout must account for reversed pin order; direct substitution without board revision is not possible. However, their shared TO-225 footprint allows mechanical mounting compatibility with adjusted trace routing.

What is the DC current gain specification for BD680 at typical operating conditions?

The BD680 specifies minimum DC current gain (h_FE) of 750 at I_C = 1.5 A and V_CE = 3.0 Vdc, per the Electrical Characteristics table in the onsemi BD676/D datasheet. This high gain enables efficient base drive - for instance, only ~2 mA base current is needed to sustain 1.5 A collector current - making BD680 well-suited for microcontroller-driven switching applications.

BD680 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-225AA, TO-126-3

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: PNP - Darlington

Current - Collector (Ic) (Max):: 4 A

Voltage - Collector Emitter Breakdown (Max):: 80 V

Vce Saturation (Max) @ Ib, Ic:: 2.5V @ 30mA, 1.5A

Current - Collector Cutoff (Max):: 500µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 750 @ 1.5A, 3V

Power - Max:: 40 W

Frequency - Transition:: -

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126

BD680 FAQ

1.How can I place an order for BD680 through Aetrix?

Please submit a Request for Quotation (RFQ) for BD680 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for BD680 reliable?

The price and inventory of BD680 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BD680 is usually 5 days.

3.What payment methods are accepted for BD680?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BD680 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BD680?

BD680 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BD680 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for BD680?

For technical support, including BD680 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BD680 requirements.

6.How does Aetrix verify that BD680 is sourced from the original manufacturer or authorized distributors?

All BD680 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BD680 meets industry standards.

7.What is the process for return or replacement of BD680?

All BD680 units undergo pre-shipment inspection (PSI). If there is an issue with BD680, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The BD680 part is unused and in its original packaging.

Return procedure for BD680:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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