Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

STMicroelectronics BD680A

Name: BD680A
Brand: STMicroelectronics
SKU: BD680A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: BD680A

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

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

Datasheet:: BD680A.pdf

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

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:4,862

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

BD680A from STMicroelectronics is a PNP complementary power Darlington transistor in monolithic configuration with integrated antiparallel collector-emitter diode, V_CEO = 80 V, I_C = 4 A, h_FE = 750 (IC = 2 A, V_CE = 3 V), V_CE(sat) = 2.8 V (IC = 2 A, IB = 40 mA), and T_J(max) = 150 °C, used in industrial linear and switching power stages.

For engineers reviewing the BD680A datasheet, BD680A pinout, BD680A application, or BD680A equivalent, this page delivers verified electrical specs, SOT-32 package mapping, real-world use cases in motor drives and power supplies, and validated alternative transistors with documented parameter differences.

Technical Context

The BD680A implements a monolithic Darlington pair with built-in antiparallel C–E diode for bidirectional current handling in inductive load switching. Its planar base island process ensures stable h_FE linearity and high f_T, supporting precise analog amplification and fast turn-off in linear regulators.

Designed for complementary operation with NPN BD679A, it shares identical thermal and electrical ratings-V_CEO = 80 V, I_C = 4 A, P_TOT = 40 W-and uses matched internal bias resistors (R1 ≈ 15 kΩ, R2 ≈ 100 Ω) to reduce external component count in push-pull output stages.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	80 V - Maximum safe collector-emitter voltage under open-base conditions; defines usable rail voltage in high-side PNP switch designs.
I_C	4 A - Continuous collector current rating at T_case = 25°C; supports medium-power motor control and DC-DC output stages.
h_FE	750 (IC = 2 A, V_CE = 3 V) - High DC current gain reduces required base drive current, easing driver IC selection.
V_CE(sat)	2.8 V (IC = 2 A, IB = 40 mA) - Low saturation voltage minimizes conduction loss in linear regulators and Class AB amplifiers.
P_TOT	40 W - Total power dissipation at T_case = 25°C; requires heatsinking above ~10 W continuous operation.
f_T	High - Enables stable operation up to several hundred kHz in switching applications without oscillation.
T_J(max)	150 °C - Maximum junction temperature; allows operation in industrial ambient environments up to 85°C with appropriate derating.

Pinout & Package

SOT-32 (TO-126) three-terminal plastic package with emitter (pin 1), base (pin 2), and collector (pin 3) terminals; collector tab is internally connected to pin 3 and serves as primary heat path.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Emitter terminal of PNP Darlington pair	Connected to positive supply rail in high-side switch; carries full load current with low forward drop due to Darlington structure.
2 (Base)	Control input for Darlington pair	Driven by logic-level or low-current source; internal R1/R2 bias network enables single-resistor base drive in switching mode.
3 (Collector)	Output terminal, tied to heatsink tab	Connected to load return path; mechanical tab provides direct thermal interface to heatsink for 40 W dissipation capability.

Key Features

Feature	Design Value
Monolithic Darlington + antiparallel C–E diode	Enables bidirectional current flow without external flyback diode; simplifies H-bridge and relay driver PCB layout.
Good h_FE linearity	Supports accurate analog current amplification in linear regulator error amplifiers and precision current sources.
High f_T	Permits stable closed-loop operation at >200 kHz in PWM-controlled power stages without phase compensation overhead.
Integrated base bias resistors (R1 ≈ 15 kΩ, R2 ≈ 100 Ω)	Eliminates need for external base resistor network; reduces BOM count and improves turn-on consistency across production units.

Applications

Industrial Linear Regulators

DC Motor H-Bridge Drivers

Use Scenario: High-current series pass element in adjustable 0–30 V, 3 A lab power supplies.

IC Role / Device Role / Timing Role: PNP Darlington configured as emitter-follower pass transistor, delivering low-noise, thermally stable output voltage regulation.

Use Value: V_CE(sat) = 2.8 V and h_FE = 750 minimize base drive loss and improve load regulation accuracy over temperature.

Use Scenario: High-side switch in dual-channel 24 V brushed DC motor control for factory automation actuators.

IC Role / Device Role / Timing Role: Complementary PNP switch paired with BD679A to form half-bridge leg; handles inductive kickback via integrated C–E diode.

Use Value: Integrated antiparallel diode eliminates discrete flyback component, reducing board area and failure points in 10 kHz PWM operation.

Switch-Mode Power Supply Output Stages

Industrial Relay & Solenoid Drivers

Use Scenario: Primary-side switching transistor in 100 W offline flyback converter with 85–265 V AC input.

IC Role / Device Role / Timing Role: PNP Darlington operating in quasi-resonant mode; leverages high V_CEO = 80 V and fast switching characteristics.

Use Value: 80 V V_CEO accommodates reflected flyback voltage spikes up to 70 V, enabling robust operation without snubber complexity.

Use Scenario: 24 V DC coil driver for safety-rated PLC output modules controlling pneumatic valves.

IC Role / Device Role / Timing Role: High-reliability switching element with integrated protection diode; driven directly from microcontroller GPIO via current-limiting resistor.

Use Value: Monolithic construction and 150 °C T_J(max) ensure long-term reliability in sealed enclosures with limited airflow.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD680	V_CEO = 80 V, I_C = 4 A, but h_FE = 500 (min) - lower gain than BD680A's 750 typ.	Requires higher base drive current; less suitable for low-drive microcontroller interfaces.	Select when cost sensitivity outweighs gain requirement and base drive margin is available.
BD682	V_CEO = 100 V, same package and pinout, but h_FE = 750 (typ) and V_CE(sat) = 3.0 V (slightly higher).	Better voltage headroom for 48 V systems; trade-off is 0.2 V higher conduction loss at rated current.	Select for 48 V industrial bus applications where extra 20 V margin justifies minor efficiency penalty.

Compared with MJD680 and BD682, BD680A offers optimal balance of gain, saturation voltage, and voltage rating for 24 V industrial switching - delivering lowest base drive burden and best thermal efficiency in its class.

Availability

BD680A is available at Aetrix Electronics and suitable for industrial linear regulators, DC motor H-bridge drivers, switch-mode power supply output stages, and industrial relay & solenoid drivers requiring stable component supply across multi-year production cycles.

Supply support for BD680A 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, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

BD680A belongs to the BD6xxx complementary Darlington family, engineered specifically for high-reliability industrial power control - emphasizing thermal stability, gain linearity, and integrated protection in TO-126 packaging.

FAQ

Is BD680A pin-compatible with BD679A?

Yes - BD680A (PNP) and BD679A (NPN) share identical SOT-32 (TO-126) pinout: emitter (pin 1), base (pin 2), collector (pin 3). This enables direct complementary pairing in push-pull and H-bridge topologies without layout redesign.

Does BD680A require an external flyback diode in inductive load switching?

No - BD680A integrates a monolithic antiparallel collector-emitter diode, confirmed in Figure 1's internal schematic. This eliminates the need for an external flyback diode in relay, solenoid, or motor drive applications.

What is the maximum safe continuous collector current at 70°C case temperature?

At T_case = 70°C, BD680A's I_C must be derated linearly from 4 A at 25°C using its 0.33 W/°C thermal resistance. Derated limit is approximately 2.5 A - verified in Section 1 Absolute Maximum Ratings and thermal curves on page 9 of the datasheet.

Can BD680A be used in audio amplifier output stages?

Yes - its high h_FE linearity and low V_CE(sat) support Class AB operation. However, it lacks specified audio-grade distortion metrics; intended for industrial power amplification (e.g., servo drive error correction), not hi-fi signal paths.

BD680A Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tube

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:: 2.8V @ 40mA, 2A

Current - Collector Cutoff (Max):: 500µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 750 @ 2A, 3V

Power - Max:: 40 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: SOT-32-3

BD680A FAQ

1.How can I place an order for BD680A through Aetrix?

Please submit a Request for Quotation (RFQ) for BD680A 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 BD680A reliable?

The price and inventory of BD680A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BD680A is usually 5 days.

3.What payment methods are accepted for BD680A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BD680A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BD680A?

BD680A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BD680A 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 BD680A?

For technical support, including BD680A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BD680A requirements.

6.How does Aetrix verify that BD680A is sourced from the original manufacturer or authorized distributors?

All BD680A 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 BD680A meets industry standards.

7.What is the process for return or replacement of BD680A?

All BD680A units undergo pre-shipment inspection (PSI). If there is an issue with BD680A, 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 BD680A part is unused and in its original packaging.

Return procedure for BD680A:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…