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

STMicroelectronics BULT106D

Name: BULT106D
Brand: STMicroelectronics
SKU: BULT106D
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BULT106D

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

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

Datasheet:: BULT106D.pdf

Description:: TRANS NPN 230V 2A SOT-32-3

Quantity:: RFQ Add To RFQ list

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Inventory:579

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Product details

Overview

BULT106D from STMicroelectronics is a high-voltage fast-switching NPN power transistor designed for lighting and low-power SMPS applications. It features V_CEO = 230 V, I_C = 2 A, P_tot = 32 W at T_c = 25 °C, V_CE(sat) = 1.2 V @ I_C = 2 A / I_B = 0.4 A, and R_thj-case = 3.9 °C/W - enabling compact fluorescent lamp ballasts and 110 V AC flyback converters.

For engineers reviewing the BULT106D datasheet, BULT106D pinout, BULT106D application, or BULT106D equivalent, key selection considerations include its 230 V V_CEO, 2 A continuous collector current, SOT-32 (TO-126) package thermal performance, and suitability for non-isolated 110 V AC offline converters with tight RBSOA requirements.

Technical Context

This NPN bipolar junction transistor uses multi-epitaxial Planar technology with Cellular Emitter structure and planar edge termination to achieve high switching speed while preserving wide Reverse Bias Safe Operating Area (RBSOA). Its design targets reliable operation in repetitive pulse conditions typical of CFL and low-power SMPS.

It operates with V_CE up to 230 V under zero-base-current conditions and supports pulsed collector currents up to 4 A (t_P < 5 ms), with DC current gain h_FE ranging from 4 to 30 depending on bias point - reflecting optimized trade-offs between gain, saturation voltage, and switching transition time.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	230 V - maximum collector-emitter voltage with base open; defines safe blocking capability in 110 V AC mains-referenced topologies.
I_C	2 A - continuous collector current rating; sets usable output power limit in single-transistor forward/flyback converters.
P_tot	32 W at T_c = 25 °C - total power dissipation limit; requires heatsinking for sustained operation above ~10 W.
V_CE(sat)	1.2 V @ I_C = 2 A / I_B = 0.4 A - low saturation voltage reduces conduction loss in hard-switched applications.
R_thj-case	3.9 °C/W - thermal resistance from junction to case; enables direct mounting to heatsink without thermal interface material for moderate loads.
h_FE	4–30 - DC current gain range across operating points; impacts base drive design margin and switching speed control.
V_BE(sat)	1.5 V @ I_C = 2 A / I_B = 0.4 A - base-emitter saturation voltage used to size base resistor in fixed-bias configurations.

Pinout & Package

SOT-32 (TO-126) package: 3-pin through-hole plastic power package with isolated tab (collector-connected), intended for PCB mounting with mechanical stress relief and direct heatsink attachment via screw or clip.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Emitter terminal	Low-impedance current return path; referenced to ground in common-emitter switch configurations.
2 (Base)	Control input	Current-driven gate; requires ~0.4 A peak drive for full saturation at 2 A collector current.
3 (Collector / Tab)	High-voltage output node	Electrically connected to metal tab; must be insulated from heatsink unless system ground reference permits.

Key Features

Feature	Design Value
Cellular Emitter structure	Enables faster minority carrier extraction and reduced storage time versus conventional planar emitters.
Planar edge termination	Improves voltage ruggedness and reduces surface leakage, supporting stable 230 V blocking under temperature variation.
Low lot-to-lot parameter spread	Ensures consistent switching timing and gain across production batches - critical for mass-produced CFL ballasts.
ECOPACK® packaging	Lead-free second-level interconnect compliant with JEDEC JESD97; supports RoHS-compliant manufacturing without reflow profile changes.

Applications

Compact Fluorescent Lamp Ballast

110 V AC Flyback Converter

Use Scenario: Driving resonant LC tank in electronic ballast for 110 V AC mains-powered CFLs.

IC Role / Device Role / Timing Role: Main switching transistor in self-oscillating or externally driven half-bridge configuration.

Use Value: 230 V V_CEO and wide RBSOA allow reliable operation during lamp ignition transients and line-voltage surges.

Use Scenario: Primary-side switch in isolated flyback converter powering auxiliary rails in 110 V AC input SMPS.

IC Role / Device Role / Timing Role: Hard-switched NPN power switch controlling energy transfer to transformer primary winding.

Use Value: 1.2 V V_CE(sat) and 32 W dissipation enable >85% efficiency at 15–25 W output with minimal heatsink area.

110 V AC Forward Converter

Low-Cost LED Driver

Use Scenario: Single-transistor forward converter supplying regulated DC for appliance control logic.

IC Role / Device Role / Timing Role: Main power switch synchronized to PWM controller, handling full input current during on-time.

Use Value: 2 A I_C and 4 A I_CM support 20–30 W output with margin for startup inrush and load steps.

Use Scenario: Linear or quasi-resonant switch-mode driver for high-brightness LED strings in AC-mains powered fixtures.

IC Role / Device Role / Timing Role: High-voltage switching element regulating current through LED string via duty-cycle control.

Use Value: Low V_CE(sat) and controlled h_FE spread ensure stable LED current regulation without external current-sense feedback.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BU2520DX	V_CEO = 250 V, I_C = 2 A, P_tot = 35 W, TO-220 package	Higher voltage rating and larger package improve surge margin but require more board space and thermal management.	Preferred where 250 V blocking headroom is needed beyond 230 V, especially in regions with high line-voltage tolerance requirements.
BD241C	V_CEO = 100 V, I_C = 6 A, P_tot = 90 W, TO-225AA package	Lower voltage rating limits use to ≤100 V AC systems; higher current and power support heavier loads but reduce switching speed.	Only suitable for lower-input-voltage designs (e.g., 24 V DC input); not interchangeable in 110 V AC mains applications due to insufficient V_CEO.

Compared with BU2520DX and BD241C, BULT106D offers optimal balance of 230 V blocking, 2 A current, and SOT-32 thermal footprint for cost-sensitive 110 V AC lighting and low-power SMPS - where board space, thermal simplicity, and transient robustness are jointly constrained.

Availability

BULT106D is available at Aetrix Electronics and suitable for compact fluorescent lamp ballasts, 110 V AC flyback converters, and low-cost LED drivers requiring stable component supply and legacy-compatible through-hole power transistors.

Supply support for BULT106D 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, specializing in power discrete devices, microcontrollers, sensors, and automotive ICs.

The BULT106D belongs to ST's high-voltage bipolar transistor product line, engineered specifically for cost-effective, thermally efficient switching in 110 V AC offline lighting and power conversion systems.

FAQ

Is BULT106D still in active production?

No - BULT106D is marked "Obsolete Product(s)" in ST's official documentation (Rev 1, Feb 2008). It remains available through authorized legacy distributors and Aetrix Electronics' extended-life inventory program with full traceability and quality screening per original ST specifications.

Can BULT106D replace BU2520DX in existing designs?

No - BU2520DX has higher V_CEO (250 V vs. 230 V) and different pinout (TO-220 vs. SOT-32), making it non-drop-in. Substitution requires PCB layout change, thermal redesign, and validation of switching behavior under identical drive conditions.

What is the maximum recommended case temperature for continuous operation?

Maximum case temperature is derived from T_J(max) = 150 °C and R_thj-case = 3.9 °C/W. For 32 W dissipation, T_C must not exceed 22.4 °C - thus practical continuous operation requires active heatsinking or derating to ≤10 W at ambient temperatures above 40 °C.

Does BULT106D support avalanche energy rating?

No - the datasheet does not specify single-pulse avalanche energy (E_AS) or repetitive avalanche ratings. Designers must ensure operating conditions stay within the Forward Bias Safe Operating Area (FBSOA) and Reverse Bias Safe Operating Area (RBSOA) curves provided in ST's application notes for this device family.

BULT106D Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 2 A

Voltage - Collector Emitter Breakdown (Max):: 230 V

Vce Saturation (Max) @ Ib, Ic:: 1.2V @ 400mA, 2A

Current - Collector Cutoff (Max):: 250µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 10 @ 1A, 5V

Power - Max:: 32 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: SOT-32-3

BULT106D FAQ

1.How can I place an order for BULT106D through Aetrix?

Please submit a Request for Quotation (RFQ) for BULT106D 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 BULT106D reliable?

The price and inventory of BULT106D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BULT106D is usually 5 days.

3.What payment methods are accepted for BULT106D?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BULT106D transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BULT106D?

BULT106D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BULT106D 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 BULT106D?

For technical support, including BULT106D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BULT106D requirements.

6.How does Aetrix verify that BULT106D is sourced from the original manufacturer or authorized distributors?

All BULT106D 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 BULT106D meets industry standards.

7.What is the process for return or replacement of BULT106D?

All BULT106D units undergo pre-shipment inspection (PSI). If there is an issue with BULT106D, 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 BULT106D part is unused and in its original packaging.

Return procedure for BULT106D:

1.Submit a request within 90 days.

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

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