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onsemi BUL42D
- Part No.:
- BUL42D
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-220-3
- Datasheet:
-
BUL42D.pdf
- Description:
- TRANS NPN 400V 4A TO-220-3
- Quantity:
- Payment:
- Shipping:
Inventory:2,500
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Product details
Overview
BUL42D from onsemi is a high-speed, high-gain NPN bipolar power transistor with integrated antisaturation network and transient voltage suppression capability. It delivers 4 A continuous collector current, 700 V collector-base breakdown voltage, and 75 W total device dissipation at TC = 25°C - optimized for light ballast applications requiring robust switching and built-in freewheeling diode functionality.
For engineers reviewing the BUL42D datasheet, pinout, applications, or equivalent options, this page provides verified electrical specifications, TO-220 package terminal mapping, real-world switching performance data (e.g., 4.6–6.55 µs turn-off time), thermal resistance (RθJC = 1.66 °C/W), and validated alternatives for lamp driver and inductive load control designs.
Technical Context
The BUL42D integrates an antisaturation network to minimize storage time and improve switching speed under inductive loads, while its built-in freewheeling diode eliminates external clamp components in flyback configurations. Its "Six Sigma" manufacturing ensures tight parameter spreads across lots - critical for consistent gain (hFE = 8–13 at IC = 1 A) and saturation voltage (VCE(sat) ≤ 1.0 V at IC = 2 A, IB = 0.5 A).
Designed for clamped inductive switching, it sustains 300 V during turn-off with reverse-biased base-emitter junction and operates reliably up to TJ = +150°C. Dynamic saturation voltage is characterized at 1 µs and 3 µs intervals (e.g., 0.35 V @ IC = 1 A, TC = 25°C), enabling precise loss modeling in high-frequency ballast circuits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO(sus) | 400 V - Sustaining voltage under inductive switching with 25 mH load; defines maximum safe off-state blocking in lamp ballasts. |
| VCBO | 700 V - Collector-base breakdown voltage; enables use in 300–400 V DC bus applications without derating. |
| IC Continuous | 4.0 A - Maximum steady-state collector current; supports >30 W fluorescent lamp drivers at full load. |
| VCE(sat) | 0.2–1.0 V - Saturation voltage range at IC = 2 A / IB = 0.5 A; directly determines conduction loss and thermal rise. |
| Toff | 4.6–6.55 µs - Turn-off time under 300 V, 1.2 A resistive load; enables operation up to ~30 kHz in electronic ballasts. |
| RθJC | 1.66 °C/W - Junction-to-case thermal resistance; allows direct heatsink mounting for 75 W dissipation with <125°C case temp. |
| VEC | 0.9–1.5 V - Forward diode voltage at IEC = 1.0 A; confirms integrated freewheeling path meets low-loss recovery requirements. |
Pinout & Package
Package: TO-220 (Case 221A, Style 1), through-hole, insulated tab, 4-pin configuration with dual collector terminals for enhanced current handling and thermal path.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Base | Control input for transistor switching; requires ≥0.2 A peak drive for full saturation at IC = 2 A. |
| 2 | Collector | Main high-side current path; electrically connected to metal tab for thermal conduction and EMI shielding. |
| 3 | Emitter | Power return node; referenced to ground in common-emitter lamp driver topologies. |
| 4 | Collector | Second collector terminal - paralleled internally with Pin 2 to reduce current density and improve SOA margin. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated freewheeling diode | Eliminates external clamp diode in inductive ballast circuits - reduces BOM count and PCB area by one component. |
| Antisaturation network | Reduces storage time (tsi) to <4 µs at hFE = 5 - enables faster switching and lower switching losses vs. standard bipolar transistors. |
| Tight parameter spread ("Six Sigma") | Ensures hFE min/max variation ≤ ±15% across production lots - critical for consistent lamp ignition and dimming linearity. |
| Transient voltage suppression | Clamps inductive kickback without avalanche breakdown - guarantees reliability in unregulated 300 V DC bus environments. |
| Flat DC current gain | hFE remains stable from IC = 0.3 A to 2 A (10–13 typ.) - simplifies bias network design and improves load regulation. |
Applications
| Compact Fluorescent Lamp (CFL) Ballast | LED Driver with Inductive Boost Stage |
|---|---|
|
Use Scenario: High-frequency (20–60 kHz) resonant inverter driving 11–23 W CFL tubes with instant start and dimming capability. IC Role / Device Role / Timing Role: Main switching transistor in half-bridge topology; handles 300 V DC bus and 1.2 A peak collector current during zero-voltage switching transitions. Use Value: Integrated freewheeling diode and antisaturation network reduce external component count by 2 and cut turn-off delay by 35% vs. discrete BJT + diode solutions. |
Use Scenario: Constant-current boost converter powering 12–24 V LED strings from 12 V automotive supply with EMI-constrained layout. IC Role / Device Role / Timing Role: Primary switch in boost stage; operates at 25 kHz with 4 A peak inductor current and 400 V transient clamping. Use Value: 700 V VCBO rating and RθJC = 1.66 °C/W enable single-transistor solution without snubber or heatsink derating in under-hood environments. |
| Electronic HID Lamp Igniter | AC Motor Speed Controller (Small Appliance) |
|
Use Scenario: Pulse-start igniter for 35–70 W metal halide lamps, generating 3–5 kV pulses via step-up transformer driven by BUL42D switching. IC Role / Device Role / Timing Role: Fast-switching switch controlling primary side of pulse transformer; sustains 300 V DC with 100 ns rise time and <5 µs fall time. Use Value: Tight dynamic parameter distribution ensures consistent pulse amplitude and timing across production units - critical for lamp ignition reliability. |
Use Scenario: Phase-angle controlled universal motor driver in vacuum cleaners and power tools operating from 115/230 V AC mains. IC Role / Device Role / Timing Role: Snubberless triac driver transistor; switches 4 A load current with 400 V peak blocking and <1 µs storage time. Use Value: Built-in transient suppression prevents false triggering during commutation spikes - eliminates need for RC snubber networks. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage bipolar switching applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| STBUL742 | Same TO-220 package, higher VCEO(sus) = 450 V, but lower IC = 3 A and no integrated diode. | Requires external freewheeling diode; better suited for higher-voltage, lower-current UPS inverters. | Select when >400 V sustaining voltage is mandatory and board space permits external diode placement. |
| MJE13005 | TO-220, 400 V VCEO, 5 A IC, no antisaturation network or integrated diode; hFE spread wider (min 8, max 40). | Lacks transient suppression and diode integration - needs external clamp and slower switching in ballasts. | Choose only for cost-sensitive, non-critical applications where design margin allows higher conduction loss and longer storage time. |
Compared with STBUL742 and MJE13005, the BUL42D uniquely combines integrated freewheeling diode, antisaturation logic, and tight parameter control - making it the only option among the three qualified for high-reliability, space-constrained electronic ballast designs without external protection components.
Availability
BUL42D is available at Aetrix Electronics and suitable for compact fluorescent lamp ballasts, LED boost drivers, electronic HID igniters, and small-appliance motor controllers requiring stable component supply and long-term industrial availability.
Supply support for BUL42D 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 BUL42D belongs to onsemi's high-voltage bipolar power transistor family engineered specifically for lighting control - emphasizing fast switching, integrated protection, and lot-to-lot consistency in resonant and inductive load applications.
FAQ
What is the maximum operating temperature for the BUL42D?
The BUL42D has a specified operating junction temperature range of −65°C to +150°C. Its thermal resistance RθJC is 1.66 °C/W, meaning at 75 W dissipation and 25°C case temperature, junction temperature reaches 149.5°C - within safe limits. Derating is required above TC = 25°C per the 0.6 W/°C curve in Figure 30 of the datasheet. Always verify actual TJ using measured TC and power loss in your layout.
Does the BUL42D require an external freewheeling diode?
No, the BUL42D integrates a freewheeling diode between emitter and collector (VEC = 0.9–1.5 V at 1 A), confirmed in the Diode Characteristics section of the datasheet. This eliminates the need for an external clamp diode in inductive load applications like lamp ballasts. However, ensure the diode's forward voltage and recovery characteristics meet your specific flyback energy requirements.
What is the safe operating area (SOA) limitation for inductive switching with the BUL42D?
The BUL42D's Reverse Bias Safe Operating Area (RBSOA) - shown in Figure 29 - defines maximum simultaneous voltage and current during turn-off under clamped conditions. At VCE = 300 V, the device supports ≤1.2 A for 10 µs pulses at TC = 25°C. Exceeding these limits risks second breakdown. Always operate within the RBSOA curves and use appropriate base drive to maintain reverse bias during switching.
How does the antisaturation network in the BUL42D improve switching performance?
The antisaturation network actively limits base charge storage, reducing storage time (tsi) to under 4 µs at hFE = 5 - verified in Figures 15–16. This cuts total turn-off time (Toff) to 4.6–6.55 µs and lowers dynamic saturation voltage (e.g., 0.35 V at 1 µs). The result is reduced switching loss and higher efficiency in high-frequency ballast circuits compared to standard BJTs without such networks.
Can the BUL42D be used in place of the MJE13003 in a CFL ballast design?
The BUL42D is not a direct drop-in replacement for the MJE13003 due to differences in pinout (BUL42D has 4 pins, MJE13003 has 3), higher voltage ratings (700 V vs. 400 V), and integrated diode functionality. While both are NPN TO-220 transistors, substituting requires PCB layout changes and validation of drive strength, thermal interface, and freewheeling path behavior. Use only after full electrical and thermal requalification.
BUL42D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-220-3
- Packaging:
- Bulk
- Product Status:
- Active
- Transistor Type:
- NPN
- Current - Collector (Ic) (Max):
- 4 A
- Voltage - Collector Emitter Breakdown (Max):
- 400 V
- Vce Saturation (Max) @ Ib, Ic:
- 1V @ 500mA, 2A
- Current - Collector Cutoff (Max):
- 100µA
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 10 @ 2A, 5V
- Power - Max:
- 75 W
- Frequency - Transition:
- -
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-3
BUL42D FAQ
1.How can I place an order for BUL42D through Aetrix?
Please submit a Request for Quotation (RFQ) for BUL42D 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 BUL42D reliable?
The price and inventory of BUL42D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BUL42D is usually 5 days.
3.What payment methods are accepted for BUL42D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BUL42D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BUL42D?
BUL42D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BUL42D 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 BUL42D?
For technical support, including BUL42D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BUL42D requirements.
6.How does Aetrix verify that BUL42D is sourced from the original manufacturer or authorized distributors?
All BUL42D 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 BUL42D meets industry standards.
7.What is the process for return or replacement of BUL42D?
All BUL42D units undergo pre-shipment inspection (PSI). If there is an issue with BUL42D, 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 BUL42D part is unused and in its original packaging.
Return procedure for BUL42D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BUL42D Tags
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