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

STMicroelectronics BUL3N7

Name: BUL3N7
Brand: STMicroelectronics
SKU: BUL3N7
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BUL3N7

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: BUL3N7.pdf

Description:: TRANS NPN 400V 3A TO-220

Quantity:: RFQ Add To RFQ list

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Inventory:9,545

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Product details

Overview

BUL3N7 from STMicroelectronics is a medium-voltage, fast-switching NPN power transistor designed for high-frequency electronic ballasts in compact fluorescent lamps (CFLs). It features V_CES = 700 V, I_C = 3 A, t_r = 80 ns, t_f = 100 ns, and R_thJ-case = 2.08 °C/W - enabling reliable operation in HF inverter stages coupled with complementary BUL3P5.

For engineers reviewing the BUL3N7 datasheet, BUL3N7 pinout, BUL3N7 application, or BUL3N7 equivalent, key selection criteria include switching speed under inductive load (t_s = 450 ns), rugged RBSOA, V_CEO(sus) = 400 V sustaining capability, and TO-220 thermal performance for CFL driver thermal management.

Technical Context

The BUL3N7 employs Multi-Epitaxial Planar technology with Cellular Emitter structure and planar edge termination to simultaneously optimize switching speed and wide Reverse Bias Safe Operating Area (RBSOA). Its design targets HF ballast inverters operating at 20–60 kHz with inductive loads and clamped voltage transients.

It delivers V_CE(sat) = 0.5 V at I_C = 0.7 A / I_B = 0.1 A and h_FE = 10–34 across I_C = 10 mA to 2 A, supporting stable base-driven switching without active gate control. The device is explicitly paired with BUL3P5 in push-pull half-bridge topologies for CFL lamp driving.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CES	700 V - supports DC bus voltages up to 450 V after rectification with margin for transient spikes in CFL ballasts.
I_C (continuous)	3 A - sustains RMS current in 20–60 kHz half-bridge output stage driving 15–40 W lamps.
t_r/t_f	80 ns / 100 ns - enables efficient switching at >30 kHz with low turn-on/turn-off losses in resistive-load test conditions.
t_s (inductive)	450 ns - critical for safe commutation in inductive resonant ballast circuits with L = 1 mH and V_clamp = 200 V.
R_thJ-case	2.08 °C/W - allows 60 W dissipation at T_C = 25°C; requires heatsink for sustained 3 A operation in enclosed CFL fixtures.
h_FE	10–34 - provides predictable base drive requirements across operating current range, simplifying fixed-bias design.

Pinout & Package

Package: TO-220 (3-pin, straight lead, insulated tab). Mounting surface is electrically connected to collector (Pin 2). Standard JEDEC TO-220 mechanical dimensions per STMicroelectronics datasheet rev.1 (Dec 2005).

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (Emitter)	Current sink terminal	Connected to ground or low-side return path; carries full load current with minimal voltage drop (V_BE(sat) ≤ 1.3 V).
Pin 2 (Collector)	High-voltage switch node	Electrically tied to heatsink mounting surface; handles 700 V blocking and 3 A conduction in half-bridge output stage.
Pin 3 (Base)	Control input	Receives current-limited drive (I_B ≤ 1.5 A peak); requires external base resistor for fixed-current bias in self-oscillating ballast designs.

Key Features

Feature	Design Value
Cellular Emitter + Planar Edge Termination	Enables simultaneous high dV/dt immunity and wide RBSOA - critical for reliability during lamp ignition surges in CFLs.
Low Lot-to-Lot Parameter Spread	Ensures consistent t_s, V_CE(sat), and h_FE across production batches - reduces need for post-manufacturing binning in mass-produced ballasts.
ECOPACK® Lead-Free Construction	Meets RoHS Directive 2002/95/EC; second-level interconnect marked on package per JESD97 for traceable compliance.
High Switching Speed (t_r = 80 ns)	Reduces switching loss in 20–60 kHz HF inverters, improving system efficiency over slower bipolar alternatives like BU2508DX.

Applications

Compact Fluorescent Lamp (CFL) Ballast

Electronic HID Lamp Igniter

Use Scenario: High-frequency (20–60 kHz) half-bridge inverter driving 15–40 W CFL tubes with resonant start circuitry.

IC Role / Device Role / Timing Role: NPN switching element in push-pull topology; switches at fixed frequency determined by LC tank; handles lamp ignition surge currents.

Use Value: V_CEO(sus) = 400 V and t_s = 450 ns ensure safe commutation during lamp striking, avoiding secondary breakdown.

Use Scenario: Ignition pulse generator in 70–150 W metal halide or sodium vapor lamps using series-resonant startup.

IC Role / Device Role / Timing Role: Fast-switching high-voltage switch triggering high-voltage pulse transformer; operates in burst-mode with <5 ms peak conduction.

Use Value: I_CM = 6 A peak and V_CES = 700 V support 3–5 kV ignition pulses without derating.

DC-AC Inverter for LED Drivers

Induction Heating Half-Bridge

Use Scenario: Low-cost isolated AC output stage for constant-current LED drivers requiring galvanic isolation via high-frequency transformer.

IC Role / Device Role / Timing Role: Primary-side switch in flyback or forward converter operating at 30–50 kHz; driven by self-oscillating or discrete logic.

Use Value: R_thJ-case = 2.08 °C/W and P_TOT = 60 W allow continuous 2 A operation with modest heatsinking in enclosed LED modules.

Use Scenario: Medium-power (500–1000 W) induction cooktop half-bridge operating at 20–40 kHz with parallel-resonant tank.

IC Role / Device Role / Timing Role: Main switching transistor handling 3 A RMS current and repetitive 400 V transients during zero-voltage switching transitions.

Use Value: Wide RBSOA and low t_f = 100 ns minimize switching losses and improve thermal stability under variable load conditions.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BU2508DX	V_CES = 800 V, t_r = 150 ns, t_f = 200 ns - slower but higher voltage rating.	Used in TV horizontal deflection; less optimized for HF ballast SOA and thermal cycling.	Prefer for 600+ V DC bus systems where switching speed is secondary to voltage margin.
ST13007	V_CES = 400 V, I_C = 8 A, t_r = 120 ns - lower voltage, higher current, slower switching.	Designed for SMPS primary side; lacks RBSOA optimization for resonant lamp ignition.	Choose only if operating V_CE < 300 V and thermal headroom is abundant; not suitable for 400 V sustaining applications.

Compared with BU2508DX and ST13007, the BUL3N7 uniquely balances 700 V blocking, sub-100 ns rise time, and rugged RBSOA - making it purpose-built for thermally constrained, high-reliability CFL ballast inverters where both voltage margin and switching speed are non-negotiable.

Availability

BUL3N7 is available at Aetrix Electronics and suitable for compact fluorescent lamp ballasts, electronic HID igniters, and medium-power DC-AC inverters requiring stable component supply and legacy-compatible TO-220 packaging.

Supply support for BUL3N7 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 industrial, automotive, and consumer markets.

The BUL3N7 belongs to ST's high-voltage bipolar power transistor product line, engineered specifically for energy-efficient lighting systems - emphasizing fast switching, thermal robustness, and lot-to-lot consistency in cost-sensitive, high-volume lighting applications.

FAQ

Is BUL3N7 still in active production?

No - STMicroelectronics has marked BUL3N7 as obsolete (per datasheet revision history and official product status). Aetrix Electronics maintains limited legacy stock and supports last-time-buy programs with full traceability and extended warranty for qualified industrial users.

Can BUL3N7 be used in place of BUL3P5?

No - BUL3N7 is an NPN transistor; BUL3P5 is its complementary PNP counterpart. They serve opposite roles in push-pull configurations. Swapping them would cause immediate failure due to reversed polarity and mismatched gain/switching characteristics.

What is the maximum recommended case temperature for continuous operation?

The absolute maximum junction temperature is 150°C. With R_thJ-case = 2.08 °C/W and P_TOT = 60 W at T_C = 25°C, the practical max case temperature for 3 A continuous operation is 85°C - requiring a heatsink that limits thermal resistance to ≤15 °C/W to stay within safe SOA limits.

Does BUL3N7 require a base resistor in CFL ballast circuits?

Yes - the datasheet specifies I_B = 0.1–0.2 A for saturation at I_C = 0.7–1 A. A fixed base resistor (e.g., 1.5–2.2 kΩ for 12–15 V drive) is standard in self-oscillating CFL ballasts to ensure stable h_FE-dependent switching and prevent thermal runaway.

BUL3N7 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):: 3 A

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

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 200mA, 1A

Current - Collector Cutoff (Max):: 100µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 18 @ 700mA, 5V

Power - Max:: 60 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

BUL3N7 FAQ

1.How can I place an order for BUL3N7 through Aetrix?

Please submit a Request for Quotation (RFQ) for BUL3N7 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 BUL3N7 reliable?

The price and inventory of BUL3N7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BUL3N7 is usually 5 days.

3.What payment methods are accepted for BUL3N7?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BUL3N7 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BUL3N7?

BUL3N7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BUL3N7 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 BUL3N7?

For technical support, including BUL3N7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BUL3N7 requirements.

6.How does Aetrix verify that BUL3N7 is sourced from the original manufacturer or authorized distributors?

All BUL3N7 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 BUL3N7 meets industry standards.

7.What is the process for return or replacement of BUL3N7?

All BUL3N7 units undergo pre-shipment inspection (PSI). If there is an issue with BUL3N7, 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 BUL3N7 part is unused and in its original packaging.

Return procedure for BUL3N7:

1.Submit a request within 90 days.

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

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