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

STMicroelectronics BUL804

Name: BUL804
Brand: STMicroelectronics
SKU: BUL804
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BUL804

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: BUL804.pdf

Description:: TRANS NPN 450V 4A TO-220

Quantity:: RFQ Add To RFQ list

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Inventory:9,931

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Product details

Overview

BUL804 from STMicroelectronics is a high-voltage fast-switching NPN power transistor designed for PFC in high-frequency electronic ballasts using half-bridge voltage-fed topology. It features 800 V V_CES, 4 A continuous collector current, 70 W total dissipation at T_c = 25°C, and sub-microsecond switching times (t_s = 0.6 µs typ., t_f = 0.1 µs typ. under inductive load), enabling efficient operation in fluorescent lamp ballast circuits.

For engineers reviewing the BUL804 datasheet, BUL804 pinout, BUL804 application, or BUL804 equivalent, key selection criteria include its 450 V V_CEO(sus) under inductive switching, RBSOA-optimized cellular emitter structure, TO-220 package thermal resistance (R_thj-case = 1.78 °C/W), and compliance with EU Directive 2002/93/EC for environmental safety.

Technical Context

The BUL804 employs Multi-Epitaxial Planar technology with planar edge termination to simultaneously achieve high voltage blocking (800 V V_CES) and fast switching (t_s/t_f < 1 µs). Its cellular emitter design extends the reverse-biased safe operating area while maintaining low dynamic parameter spread across production lots.

It is specifically characterized for use in half-bridge voltage-fed topologies where sustained V_CE = 450 V under I_C = 100 mA with L = 25 mH inductive load, and operates up to T_J = 150°C with guaranteed h_FE ≥ 10 at I_C = 2 A.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CES	800 V - Maximum collector-emitter voltage with base open; enables direct use in 400 V DC bus PFC stages without snubbers.
I_C (continuous)	4 A - Continuous collector current rating at T_c = 25°C; supports >30 W ballast output with margin.
P_tot	70 W - Total power dissipation at case temperature 25°C; requires heatsink for sustained operation above ~15 W.
t_s/t_f (inductive)	0.6 / 0.1 µs typ. - Storage/fall times under V_CC = 300 V, I_C = 2 A, enabling >100 kHz switching in resonant ballasts.
h_FE	10–20 - DC current gain range at I_C = 2 A, V_CE = 5 V; ensures stable base drive design across temperature and process variation.
R_thj-case	1.78 °C/W - Junction-to-case thermal resistance; defines minimum heatsink requirement for thermal management.

Pinout & Package

Supplied in TO-220 package with standard 3-pin configuration: Pin 1 = Base, Pin 2 = Collector (tab), Pin 3 = Emitter. The metal tab is electrically connected to the collector and must be insulated from heatsink unless circuit topology permits common-collector mounting.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Base	Control terminal for bipolar switching; requires 0.2–0.5 A peak base drive for full saturation at I_C = 1–2.5 A.
Pin 2	Collector (Tab)	Main high-voltage power terminal; electrically tied to metal tab; mandates electrical isolation when mounted to heatsink.
Pin 3	Emitter	Reference node for base drive and current sensing; low-inductance connection critical for fast switching stability.

Key Features

Feature	Design Value
Cellular Emitter Structure	Enables wide RBSOA while preserving fast switching-critical for reliable operation during overcurrent transients in ballast half-bridges.
Planar Edge Termination	Provides stable 800 V V_CES rating with minimal voltage dependence on temperature or process variation.
Low Lot-to-Lot Parameter Spread	Ensures consistent t_s, t_f, and h_FE across manufacturing batches-reducing need for system-level tuning in volume production.
ECOPACK® Compliance	Lead-free second-level interconnect meeting JEDEC JESD97; supports RoHS-compliant assembly without reflow profile changes.

Applications

Electronic Ballast Control

PFC Half-Bridge Stage

Use Scenario: High-frequency (25–65 kHz) electronic ballast driving T5/T8 fluorescent lamps in commercial lighting fixtures.

IC Role / Device Role / Timing Role: Main switching transistor in voltage-fed half-bridge PFC stage, handling 400 V DC bus and delivering regulated lamp current.

Use Value: Sub-µs switching minimizes conduction + switching losses, enabling >90% system efficiency at full load.

Use Scenario: Active PFC pre-regulator in compact fluorescent lamp (CFL) drivers with universal AC input (90–264 VAC).

IC Role / Device Role / Timing Role: High-voltage switch in discontinuous conduction mode (DCM) PFC boost stage, synchronized to line frequency.

Use Value: 450 V V_CEO(sus) rating allows safe operation with 385 V peak rectified input plus margin, eliminating need for voltage clamping.

Inductive Load Switching

High-Voltage DC-DC Conversion

Use Scenario: Resonant inverter stage in LED driver modules requiring precise current regulation via phase-shift control.

IC Role / Device Role / Timing Role: Fast-switching power switch in series-resonant LLC topology operating at 100–300 kHz.

Use Value: Low t_s/t_f reduces dead-time losses and improves ZVS boundary, increasing light-output consistency.

Use Scenario: Isolated DC-DC converter in industrial control power supplies converting 400 V DC bus to 24 V/5 A output.

IC Role / Device Role / Timing Role: Primary-side switch in forward or half-bridge isolated topology with active clamp or RCD snubber.

Use Value: 800 V V_CES withstands reflected voltage spikes and leakage inductance energy without derating.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage NPN power transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
STW20NK50Z	500 V, 20 A MOSFET; lower gate drive complexity but higher R_DS(on) conduction loss at <1 A.	Replaces BUL804 only in new designs with gate-drive simplification priority; not drop-in due to different drive and SOA behavior.	Select if designing for zero-voltage switching (ZVS) topologies where MOSFET body diode recovery is acceptable.
BU508A	1000 V, 8 A NPN; slower switching (t_s = 3.5 µs), higher V_CE(sat) (1.5 V @ 4 A), larger TO-3P package.	Suitable for lower-frequency (<30 kHz), higher-power (>60 W) ballasts where ruggedness outweighs efficiency.	Choose for legacy systems requiring higher voltage margin or mechanical compatibility with older TO-3P footprints.

Compared with STW20NK50Z and BU508A, the BUL804 uniquely balances 800 V capability, sub-µs switching, and TO-220 thermal performance-making it optimal for cost-sensitive, high-efficiency 25–100 kHz fluorescent and LED ballast PFC stages.

Availability

BUL804 is available at Aetrix Electronics and suitable for electronic ballast control, PFC half-bridge stages, inductive load switching, and high-voltage DC-DC conversion requiring stable component supply and long-term industrial availability.

Supply support for BUL804 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 devices for automotive, industrial, and consumer markets.

The BUL804 belongs to ST's high-voltage power transistor product line, engineered specifically for energy-efficient lighting control and power factor correction in AC-DC conversion systems operating up to 100 kHz.

FAQ

Is BUL804 still in active production?

No-BUL804 is marked as Obsolete Product(s) in ST's official documentation (Rev 2, May 2006). It remains available through authorized distributors and Aetrix Electronics' legacy component program with verified date-code-controlled inventory and full traceability for ongoing production support.

What is the maximum recommended case temperature for continuous operation?

The BUL804 is rated for T_c ≤ 100°C for continuous operation at full I_C = 4 A. At T_c = 100°C, derated P_tot is approximately 39 W (calculated from R_thj-case = 1.78 °C/W and T_J(max) = 150°C), requiring a heatsink with R_thc-amb ≤ 12.8 °C/W.

Can BUL804 be used in avalanche mode?

No-the BUL804 is not rated or characterized for repetitive avalanche operation. Its V_CEO(sus) = 450 V is specified under controlled inductive switching (L = 25 mH, I_C = 100 mA), and operation beyond this condition risks single-pulse failure. External clamping is required for uncontrolled inductive energy dissipation.

Does BUL804 require a base resistor for safe turn-off?

Yes-a negative base drive or pull-down resistor (typically 10–47 Ω) is strongly recommended to ensure rapid turn-off and prevent secondary breakdown during inductive switching. Data sheet Figure 9 shows V_BE(off) = –5 V test condition, confirming need for active base discharge to achieve t_s = 0.6 µs.

BUL804 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 450 V

Vce Saturation (Max) @ Ib, Ic:: 1.2V @ 500mA, 2.5A

Current - Collector Cutoff (Max):: 250µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 10 @ 2A, 5V

Power - Max:: 70 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

BUL804 FAQ

1.How can I place an order for BUL804 through Aetrix?

Please submit a Request for Quotation (RFQ) for BUL804 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 BUL804 reliable?

The price and inventory of BUL804 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BUL804 is usually 5 days.

3.What payment methods are accepted for BUL804?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BUL804 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BUL804?

BUL804 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BUL804 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 BUL804?

For technical support, including BUL804 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BUL804 requirements.

6.How does Aetrix verify that BUL804 is sourced from the original manufacturer or authorized distributors?

All BUL804 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 BUL804 meets industry standards.

7.What is the process for return or replacement of BUL804?

All BUL804 units undergo pre-shipment inspection (PSI). If there is an issue with BUL804, 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 BUL804 part is unused and in its original packaging.

Return procedure for BUL804:

1.Submit a request within 90 days.

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

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