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

STMicroelectronics BD680

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

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Part No.:: BD680

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

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

Datasheet:: BD680.pdf

Description:: TRANS PNP DARL 80V 4A SOT-32-3

Quantity:: RFQ Add To RFQ list

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Inventory:2,070

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Product details

Overview

BD680 from STMicroelectronics is a PNP complementary power Darlington transistor in SOT-32 package, rated for V_CEO = –80 V, I_C = –4 A, and P_TOT = 40 W at T_case = 25°C, featuring monolithic Darlington configuration with integrated antiparallel collector-emitter diode and h_FE ≥ 750 at I_C = –1.5 A, V_CE = –3 V. It is used in high-current linear amplification and industrial switching circuits requiring robust thermal performance and high DC gain linearity.

For engineers reviewing the BD680 datasheet, BD680 pinout, BD680 application, or BD680 equivalent, this page delivers verified electrical specifications, validated SOT-32 terminal mapping, real-world use cases in motor control and power regulation, and technically documented alternative parts with functional differences.

Technical Context

The BD680 implements a monolithic planar-base Darlington pair with built-in antiparallel C–E diode to support bidirectional current handling in inductive load switching. Its high f_T, good h_FE linearity across I_C, and low V_CE(sat) of 2.5 V (I_C = –1.5 A, I_B = –30 mA) enable stable operation in analog amplification and hard-switching topologies.

Designed for industrial-grade reliability, it supports continuous junction temperatures up to 150°C and storage from –65°C to +150°C. The integrated base resistors (R1 ≈ 15 kΩ, R2 ≈ 100 Ω) simplify drive circuitry and improve turn-off speed compared to discrete Darlington configurations.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	–80 V: Maximum safe collector-emitter voltage under open-base condition for PNP operation
I_C	–4 A: Continuous DC collector current rating at T_case = 25°C
P_TOT	40 W: Total power dissipation capability with heatsink at 25°C case temperature
h_FE	≥750 at I_C = –1.5 A, V_CE = –3 V: High DC current gain enabling low-base-drive requirements
V_CE(sat)	2.5 V at I_C = –1.5 A, I_B = –30 mA: Low saturation voltage reduces conduction losses in switching mode
f_T	High frequency transition frequency: Enables usable bandwidth in audio and medium-speed switching applications
Integrated diode	Antiparallel C–E diode monolithically embedded: Eliminates need for external flyback diode in inductive load drivers

Pinout & Package

SOT-32 (TO-126 compatible) three-terminal plastic package with exposed collector tab for thermal mounting. Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector (tab).

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current exit node for PNP device	Connected to positive rail in high-side switch or output stage of linear amplifier
2 (Base)	Control input with internal bias network	R1 ≈ 15 kΩ and R2 ≈ 100 Ω provide self-biasing and improve turn-off speed
3 (Collector / Tab)	Main current sink and thermal interface	Exposed metal tab electrically connected to collector; must be insulated from heatsink if not referenced to ground

Key Features

Feature	Design Value
Monolithic Darlington structure	Single-die integration eliminates inter-device parameter mismatch and improves thermal coupling between stages
Integrated antiparallel C–E diode	Enables safe commutation of inductive loads without external flyback components
High h_FE linearity	Stable current gain over wide I_C range supports accurate analog current sourcing and feedback control
Planar base island technology	Improved ruggedness and consistent breakdown characteristics versus epitaxial base processes

Applications

Industrial Motor Control

Linear Power Regulation

Use Scenario: Driving 24–48 V DC brushed motors in conveyor systems and valve actuators with PWM or analog speed control.

IC Role / Device Role / Timing Role: High-current PNP Darlington switch operating in saturation and active regions for bidirectional current control.

Use Value: Integrated antiparallel diode clamps inductive kickback during PWM off-time, reducing component count and PCB area by eliminating external flyback diodes.

Use Scenario: Pass element in adjustable linear regulators delivering up to 3 A at ≤80 V input differential.

IC Role / Device Role / Timing Role: Series pass transistor regulating output voltage via base-controlled emitter current.

Use Value: High h_FE ≥750 minimizes base drive current requirement, easing design of low-power error amplifier stages.

Switched-Mode Power Supply (SMPS) Auxiliary

High-Voltage Audio Amplifier Output Stage

Use Scenario: Standby power switch or auxiliary bias supply controller in offline SMPS designs.

IC Role / Device Role / Timing Role: High-voltage PNP switch enabling fast turn-on/turn-off with integrated base resistors.

Use Value: R1/R2 network ensures reliable turn-off even with marginal drive strength, improving system stability during light-load conditions.

Use Scenario: Complementary output pair in Class AB audio amplifiers targeting 50–100 W into 4–8 Ω loads.

IC Role / Device Role / Timing Role: PNP output device delivering negative half-cycle current with matched NPN counterpart (e.g., BD679).

Use Value: Matched h_FE linearity and V_CE(sat) between BD680 and BD679 reduces crossover distortion and improves THD performance.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BD680A	V_CEO = –80 V same, but h_FE ≥ 750 at I_C = –2 A (vs. –1.5 A), V_CE(sat) = 2.8 V at higher drive	Higher current rating suits sustained >2 A loads; slightly higher saturation loss	Select BD680A when operating continuously above 1.8 A with adequate heatsinking
MJD42C	Same V_CEO (–80 V), lower I_C (–3 A), no integrated diode, TO-252 package	Requires external flyback diode; better suited for surface-mount layouts where thermal pad access is constrained	Choose MJD42C only when board space mandates SMD and external diode integration is acceptable

Compared with BD680, BD680A offers higher current capability at marginally increased V_CE(sat), while MJD42C trades integrated protection and through-hole compatibility for SMD footprint - selection depends on thermal management strategy, layout constraints, and diode integration needs.

Availability

BD680 is available at Aetrix Electronics and suitable for industrial motor control, linear power regulation, switched-mode power supply auxiliary circuits, and high-voltage audio amplifier output stages requiring stable component supply and long-term obsolescence planning.

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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, digital, and mixed-signal ICs and discrete power devices for industrial, automotive, and consumer markets.

The BD6xxx series belongs to ST's complementary power Darlington transistor product line, engineered specifically for high-reliability industrial switching and linear amplification where high h_FE, integrated protection, and thermal robustness are critical.

FAQ

What is the maximum safe operating voltage for BD680 in common-emitter configuration?

The BD680 has a guaranteed V_CEO rating of –80 V under I_B = 0 condition, meaning it can safely block up to 80 V between collector and emitter with base open. Exceeding this value risks avalanche breakdown. Derating is recommended for reliability in repetitive switching or elevated temperature environments.

Does BD680 require an external flyback diode when driving inductive loads?

No. BD680 integrates a monolithic antiparallel collector-emitter diode, explicitly designed to clamp inductive kickback during turn-off. This eliminates the need for an external flyback diode in most relay, solenoid, and DC motor drive applications, reducing BOM count and layout complexity.

How does the internal base resistor network affect drive requirements?

The BD680 includes R1 ≈ 15 kΩ (base-to-emitter) and R2 ≈ 100 Ω (base-to-collector), forming a built-in bias network that ensures reliable turn-on with modest base current and accelerates turn-off by shunting stored base charge. This reduces dependency on precise external drive strength and improves switching consistency.

Can BD680 be used in parallel with other Darlingtons for higher current capacity?

Parallel operation is not recommended due to inherent h_FE and V_BE mismatches between units, which cause current imbalance and potential thermal runaway. For higher current, use a single higher-rated device (e.g., BD680A) or implement active current-sharing circuitry with individual emitter resistors and matched thermal mounting.

BD680 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tube

Product Status:: Active

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:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: SOT-32-3

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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