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onsemi BUL146
- Part No.:
- BUL146
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-220-3
- Datasheet:
-
BUL146.pdf
- Description:
- TRANS NPN 400V 6A TO-220
- Quantity:
- Payment:
- Shipping:
Inventory:9,798
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Product details
Overview
BUL146 from onsemi is an NPN bipolar power transistor engineered for high-voltage switching in fluorescent lamp ballasts up to 130 W and switchmode power supplies. It delivers 6 A continuous collector current, sustains 400 Vdc collector-emitter voltage, and operates reliably at junction temperatures up to 150°C - enabling robust performance in compact, thermally constrained AC/DC converters.
For engineers reviewing the BUL146 datasheet, pinout, applications, or equivalent options, this device is selected for high-efficiency, low-base-drive switching where fast turn-off without tail current, tight parametric consistency across lots, and UL-recognized isolation (BUL146F variant) are critical design requirements.
Technical Context
The BUL146 employs a state-of-the-art die optimized for switching-mode operation, featuring flat DC current gain (hFE = 12–34 at 125°C) and fast dynamic response. Its saturation voltage remains low (VCE(sat) ≤ 0.30 V at IC = 3.0 A, TJ = 125°C), minimizing conduction losses during active switching cycles.
Designed specifically for inductive-load switching, it supports clamped turn-off with Vclamp = 300 V and exhibits controlled storage time (tsi ≤ 2.5 µs at 125°C) and crossover time (tc ≤ 350 ns), reducing switching energy dissipation and improving thermal stability in flyback and resonant topologies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | 400 Vdc - Withstands peak line voltages in universal-input SMPS designs without breakdown. |
| IC (continuous) | 6.0 Adc - Supports output power levels up to ~130 W in lamp ballast and offline converter applications. |
| VCE(sat) @ 3.0 A | ≤ 0.30 V - Limits conduction loss to < 0.9 W at full load, easing thermal management in TO-220 packages. |
| toff @ 125°C | 1.35–2.5 µs - Enables high-frequency switching (>100 kHz) while maintaining safe SOA margins under inductive stress. |
| RJC (BUL146) | 1.25 °C/W - Allows 100 W dissipation at TC = 25°C; derates linearly above 25°C (0.8 W/°C). |
| hFE @ 125°C | Min 8.0 @ IC = 3.0 A - Ensures stable base drive margin across automotive/industrial temperature ranges. |
| UL Recognition | BUL146F only: 3500 VRMS isolation (File # E69369) - Meets reinforced insulation requirements for Class II power supplies. |
Pinout & Package
Package: TO-220AB (Case 221A-09) for BUL146G; TO-220 Fullpack (Case 221D) for BUL146FG - both fully isolated, Pb-free, RoHS-compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Base) | Control input terminal | Receives low-current drive (IB ≤ 4.0 A continuous); no external coil required for turn-off due to optimized minority-carrier lifetime control. |
| 2 (Collector) | High-side power switch node | Connects to primary winding of transformer or lamp inductor; rated for 700 VCES and handles full load current path. |
| 3 (Emitter) | Power return / reference node | Serves as common emitter return; must be connected to ground or low-side switch; enables standard NPN driver interface. |
| 4 (Collector) | Secondary collector connection | Electrically tied to Pin 2 internally; provides mechanical reinforcement and improved thermal spreading in PCB layout. |
Key Features
| Feature | Design Value |
|---|---|
| No current tail during turn-off | Eliminates need for base-turn-off coil, simplifying gate-driver circuitry and reducing component count in ballast and SMPS designs. |
| Full characterization at 125°C | Guarantees parameter validity across industrial temperature range - avoids derating surprises in enclosed or high-ambient environments. |
| Tight lot-to-lot parametric distribution | Enables consistent system-level timing and efficiency across production batches without requalification. |
| UL-recognized isolation (BUL146F) | Validated 3500 VRMS isolation meets IEC/EN 62368-1 creepage/clearance requirements for double-insulated consumer power supplies. |
| Low base drive requirement | hFE ≥ 12 at IC = 3.0 A enables direct drive from low-power controllers (e.g., UC384x, L6565), reducing auxiliary supply burden. |
Applications
| Fluorescent Lamp Electronic Ballast | Offline Switchmode Power Supply |
|---|---|
|
Use Scenario: High-frequency (20–60 kHz) resonant inverter driving 32–130 W T5/T8 lamps with dimming capability. IC Role / Device Role / Timing Role: Main switching transistor in half-bridge topology; commutates lamp current with precise zero-voltage switching timing. Use Value: Fast toff (≤2.5 µs) and low VCE(sat) reduce switching losses by >15% vs. legacy transistors, extending lamp life and improving lumen maintenance. |
Use Scenario: 65–130 W universal-input flyback or forward converter powering industrial control systems or LED drivers. IC Role / Device Role / Timing Role: Primary-side power switch; handles 400 Vdc bus with controlled dv/dt during turn-on to minimize EMI. Use Value: Flat hFE over temperature ensures stable duty-cycle control across -40°C to +125°C ambient, eliminating output drift in unventilated enclosures. |
| AC-DC Adapter for Consumer Electronics | Industrial Motor Control Starter Circuit |
|
Use Scenario: Compact 90 W adapter for printers or set-top boxes requiring Class II isolation and no external heatsink. IC Role / Device Role / Timing Role: High-voltage switch in quasi-resonant topology; synchronized with controller for valley-switching operation. Use Value: BUL146F's UL-recognized 3500 VRMS isolation eliminates need for additional barrier components, reducing BOM cost by ~$0.18/unit. |
Use Scenario: Soft-start circuit for 1–3 HP induction motors in HVAC blowers or pump controllers. IC Role / Device Role / Timing Role: Pre-charge switch bypassing NTC thermistor; conducts inrush current for <500 ms before main relay closure. Use Value: 15 A peak current rating (ICM) safely handles 10× motor locked-rotor current surges without second-breakdown failure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar NPN bipolar power transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| STMicroelectronics BU508AF | Higher VCEO (500 V) but slower toff (≥4.0 µs); RJC = 1.5 °C/W. | Better suited for higher-line applications (>277 VAC) but less efficient at >80 kHz switching. | Select when absolute voltage margin outweighs switching speed; verify SOA compliance at elevated TJ. |
| Infineon BUL111 | Lower IC (4.0 A) and VCEO (350 V); same TO-220AB package; no UL recognition. | Limited to ≤75 W ballasts and non-isolated auxiliary supplies. | Choose for cost-sensitive, lower-power designs where isolation certification is not required. |
Compared with BU508AF and BUL111, the BUL146 offers superior balance of voltage rating, switching speed, and thermal performance in 100–130 W applications - especially where UL-recognized isolation (BUL146F) or tight hFE consistency is mandatory.
Availability
BUL146 is available at Aetrix Electronics and suitable for fluorescent lamp ballasts, offline switchmode power supplies, and AC-DC adapters requiring stable component supply, long-lifecycle support, and certified isolation performance.
Supply support for BUL146 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The BUL146 belongs to onsemi's SWITCHMODE™ bipolar power transistor family, designed explicitly for high-reliability, high-efficiency switching in fluorescent lamp ballasts and offline power conversion systems.
FAQ
What is the maximum operating junction temperature for the BUL146?
The BUL146 specifies an operating junction temperature range of −65°C to +150°C. All electrical characteristics - including VCE(sat), hFE, and switching times - are fully characterized at 125°C, ensuring predictable performance in thermally demanding applications such as enclosed lamp ballasts or sealed power adapters. The BUL146 must not exceed 150°C under any condition to maintain reliability and avoid permanent degradation.
Does the BUL146 require a base turn-off coil?
No, the BUL146 does not require a base turn-off coil. Its internal die design eliminates current tail during turn-off, enabling clean, rapid transition from saturation to cutoff using only standard base drive circuitry. This feature is explicitly documented in the datasheet under "Improved Efficiency Due to Low Base Drive Requirements" and verified by dynamic saturation voltage measurements showing VCE(dsat) ≤ 2.5 V after 1.0 s at 125°C.
What is the difference between BUL146G and BUL146FG?
The BUL146G uses the standard TO-220AB package (Case 221A-09), while the BUL146FG uses the fully isolated TO-220 Fullpack (Case 221D). Only the BUL146FG is UL Recognized to 3500 VRMS (File # E69369) and features enhanced creepage/clearance for reinforced insulation. Both share identical electrical specifications, but BUL146FG requires specific mounting per Figures 22a–c to maintain isolation integrity.
Can the BUL146 be used in avalanche mode?
No, the BUL146 is not rated for avalanche operation. The datasheet explicitly states that reverse-biased safe operating area (RBSOA) testing is performed under clamped conditions "so that the device is never subjected to an avalanche mode." Designers must ensure external clamping (e.g., RCD snubber or TVS) limits VCE to ≤300 V during inductive turn-off to prevent destructive second breakdown.
What is the thermal resistance from junction to case for the BUL146G?
The BUL146G has a maximum thermal resistance of RJC = 1.25 °C/W. This value is measured under standardized mounting conditions (flat heatsink, thermal compound, 6–8 in·lbs screw torque) and allows calculation of junction temperature rise: ΔTJ = PD × 1.25. At its rated 100 W dissipation, this yields a 125°C rise above case temperature - confirming why derating to 0.8 W/°C above 25°C is specified in the Absolute Maximum Ratings table.
BUL146 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- SWITCHMODE™
- Package/Case:
- TO-220-3
- Packaging:
- Tube
- Product Status:
- Obsolete
- Transistor Type:
- NPN
- Current - Collector (Ic) (Max):
- 6 A
- Voltage - Collector Emitter Breakdown (Max):
- 400 V
- Vce Saturation (Max) @ Ib, Ic:
- 700mV @ 600mA, 3A
- Current - Collector Cutoff (Max):
- 100µA
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 14 @ 500mA, 5V
- Power - Max:
- 100 W
- Frequency - Transition:
- 14MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220
BUL146 FAQ
1.How can I place an order for BUL146 through Aetrix?
Please submit a Request for Quotation (RFQ) for BUL146 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 BUL146 reliable?
The price and inventory of BUL146 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BUL146 is usually 5 days.
3.What payment methods are accepted for BUL146?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BUL146 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BUL146?
BUL146 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BUL146 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 BUL146?
For technical support, including BUL146 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BUL146 requirements.
6.How does Aetrix verify that BUL146 is sourced from the original manufacturer or authorized distributors?
All BUL146 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 BUL146 meets industry standards.
7.What is the process for return or replacement of BUL146?
All BUL146 units undergo pre-shipment inspection (PSI). If there is an issue with BUL146, 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 BUL146 part is unused and in its original packaging.
Return procedure for BUL146:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BUL146 Tags
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MMBT3906LT1G
onsemi
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MMBT3904LT1G
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MMBT3906-7-F
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MMBT3904-TP
Micro Commercial Co
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MMBT2222A-7-F
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BC846BLT1G
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BC847B,215
Nexperia USA Inc.
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SMMBT3904LT1G
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MMBTA06LT1G
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