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

STMicroelectronics BU810

Name: BU810
Brand: STMicroelectronics
SKU: BU810
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BU810

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: BU810.pdf

Description:: TRANS NPN DARL 400V 7A TO-220

Quantity:: RFQ Add To RFQ list

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Inventory:7,549

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Product details

Overview

BU810 from STMicroelectronics is a medium-voltage NPN Darlington transistor in TO-220 package, designed for horizontal deflection in monochrome TVs and general-purpose switching. It features 400 V V_CEO, 7 A I_C, integrated antiparallel collector-emitter diode, fast switching (t_f = 0.4 µs), and low base-drive requirement (I_B = 0.7 A for I_C = 7 A).

For engineers reviewing the BU810 datasheet, BU810 pinout, BU810 application, or BU810 equivalent, key selection criteria include V_CEO(sus) = 400 V, R_thj-case = 1.66 °C/W, integrated clamping diode, inductive switching performance at 7 A, and TO-220 mechanical compatibility with heatsink mounting.

Technical Context

The BU810 integrates a monolithic NPN Darlington pair with an antiparallel emitter-collector diode, enabling self-clamped inductive switching without external snubbers. Its multiepitaxial planar structure supports high-voltage blocking (V_CBO = 600 V) and robust surge handling (I_CM = 10 A).

Designed for hard-switched horizontal deflection circuits, it operates with V_BE(sat) = 3 V at I_C = 4 A / I_B = 200 mA and delivers t_s = 1.5 µs and t_f = 0.4 µs under L = 500 µH, V_Clamp = 250 V conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	400 V - Sustains full horizontal flyback voltage in monochrome TV deflection circuits without external clamping.
I_C	7 A continuous - Supports peak horizontal scan current in 15–20 kHz line-output stages.
t_f	0.4 µs - Enables efficient switching at 15–20 kHz with minimal turn-off loss in inductive loads.
R_thj-case	1.66 °C/W - Allows direct mounting to heatsink for thermal management in 75 W P_tot operation.
V_F	3 V @ 7 A - Integrated antiparallel diode provides bidirectional conduction path for flyback energy recovery.
V_CE(sat)	3 V @ I_C = 7 A, I_B = 0.7 A - Low saturation voltage reduces conduction loss in high-current switching nodes.

Pinout & Package

TO-220 package with vertical mounting orientation, metal tab (pin 2) electrically connected to collector, and standardized 3-pin layout for PCB through-hole insertion and heatsink attachment.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Emitter terminal of Darlington pair	Reference node for base drive and load return; isolated from heatsink when mounted with insulator.
2 (Collector/Tab)	Collector terminal and mechanical mounting surface	Electrically tied to collector; requires insulated mounting hardware to avoid shorting in grounded-heatsink configurations.
3 (Base)	Control input for Darlington pair	Low-impedance drive point requiring ~0.7 A for full 7 A output; sensitive to negative turn-off bias (V_BE(off) = −5 V).

Key Features

Feature	Design Value
Integrated antiparallel diode	Eliminates need for external flyback diode in horizontal deflection yoke circuits, reducing BOM count and board space.
Low base-drive requirement	0.7 A base current fully saturates at 7 A collector current, easing driver stage design and reducing pre-driver losses.
Fast storage/fall times	t_s = 1.5 µs and t_f = 0.4 µs enable stable 15–20 kHz operation with predictable switching loss profile.
High V_CEO(sus)	400 V sustaining voltage ensures reliable operation under transient overvoltage during horizontal retrace in CRT systems.

Applications

Horizontal Deflection in Monochrome TVs

Switching Regulators (Offline)

Use Scenario: Horizontal output stage driving CRT deflection yoke with 15.625 kHz flyback waveform.

IC Role / Device Role / Timing Role: Main switching transistor handling peak currents up to 7 A and flyback voltages up to 400 V.

Use Value: Integrated diode recovers flyback energy; fast t_f minimizes dead-time loss and improves efficiency.

Use Scenario: Primary-side switch in 20–50 W offline flyback converters with universal AC input.

IC Role / Device Role / Timing Role: High-voltage switching element operating at ≤20 kHz with self-clamped turn-off.

Use Value: V_CEO(sus) = 400 V withstands reflected output voltage + leakage spike; R_thj-case = 1.66 °C/W enables compact heatsinking.

Motor Control (DC Brushed)

General-Purpose High-Current Switching

Use Scenario: H-bridge low-side switch controlling 24 V DC brushed motors in industrial actuators.

IC Role / Device Role / Timing Role: Robust current-handling switch with integrated reverse-recovery path for inductive kickback.

Use Value: V_F = 3 V at 7 A limits clamp dissipation; t_s/t_f ensure clean commutation at ≤10 kHz PWM.

Use Scenario: Solid-state relay replacement in programmable logic controller (PLC) output modules.

IC Role / Device Role / Timing Role: Medium-voltage, medium-speed power switch interfacing microcontroller GPIO to 24–48 V loads.

Use Value: TO-220 package allows direct PCB mounting and field-serviceable replacement; I_CM = 10 A handles momentary surges.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage Darlington switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BU508A	V_CEO = 1000 V, I_C = 8 A, no integrated diode, slower t_f (0.8 µs)	Used in higher-voltage CRT deflection (e.g., color TVs); requires external flyback diode	Select when >600 V blocking is required and external diode integration is acceptable.
2SD1762	V_CEO = 400 V, I_C = 7 A, no integrated diode, faster t_f (0.25 µs), lower V_CE(sat) (2.2 V)	Common in Japanese monochrome TV designs; relies on discrete clamp network	Prefer when minimizing conduction loss is critical and board space permits external clamping components.

Compared with BU508A and 2SD1762, the BU810 uniquely combines 400 V rating, 7 A capability, and integrated diode in TO-220-reducing component count and layout complexity specifically for monochrome TV horizontal deflection, where V_CEO(sus) and self-clamping are decisive.

Availability

BU810 is available at Aetrix Electronics and suitable for horizontal deflection circuits, offline switching regulators, and DC motor control applications requiring stable component supply and legacy CRT system support.

Supply support for BU810 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, designing and manufacturing analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The BU810 belongs to ST's high-voltage bipolar power transistor product line, engineered specifically for CRT horizontal deflection and medium-frequency hard-switching applications demanding ruggedness, integrated protection, and thermal reliability.

FAQ

Is the BU810 still in active production?

No-the BU810 is marked "Obsolete Product(s)" in its official STMicroelectronics datasheet (Rev. 4, December 2000). It remains available through authorized legacy distributors and Aetrix Electronics' long-life inventory program for repair and maintenance of existing monochrome TV and industrial equipment.

Can the BU810 be used without an external heatsink?

No-its P_tot = 75 W at T_case ≤ 25 °C requires active thermal management. With R_thj-case = 1.66 °C/W, even at 25 W dissipation, junction temperature rises ~42 °C above case. A minimum 2°C/W heatsink is recommended for sustained 7 A operation.

What is the purpose of the integrated antiparallel diode?

The integrated collector-emitter diode provides a low-impedance path for inductive flyback current during transistor turn-off-eliminating the need for an external clamp diode in horizontal deflection yoke circuits and preventing destructive voltage spikes across the transistor.

How does the BU810 differ from standard NPN transistors in switching applications?

Unlike single NPN devices, the BU810 uses a Darlington configuration to achieve high current gain (h_FE ≥ 1000), enabling low base-drive current (0.7 A) for 7 A collector output. Its integrated diode and optimized switching times (t_s/t_f) are tailored for CRT flyback duty-not found in generic NPN transistors.

BU810 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN - Darlington

Current - Collector (Ic) (Max):: 7 A

Voltage - Collector Emitter Breakdown (Max):: 400 V

Vce Saturation (Max) @ Ib, Ic:: 3V @ 700mA, 7A

Current - Collector Cutoff (Max):: 1mA

DC Current Gain (hFE) (Min) @ Ic, Vce:: -

Power - Max:: 75 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

BU810 FAQ

1.How can I place an order for BU810 through Aetrix?

Please submit a Request for Quotation (RFQ) for BU810 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 BU810 reliable?

The price and inventory of BU810 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BU810 is usually 5 days.

3.What payment methods are accepted for BU810?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BU810 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BU810?

BU810 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BU810 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 BU810?

For technical support, including BU810 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BU810 requirements.

6.How does Aetrix verify that BU810 is sourced from the original manufacturer or authorized distributors?

All BU810 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 BU810 meets industry standards.

7.What is the process for return or replacement of BU810?

All BU810 units undergo pre-shipment inspection (PSI). If there is an issue with BU810, 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 BU810 part is unused and in its original packaging.

Return procedure for BU810:

1.Submit a request within 90 days.

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

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