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

onsemi BUD42D-1G

Name: BUD42D-1G
Brand: onsemi
SKU: BUD42D-1G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BUD42D-1G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-252-3, DPAK (2 Leads + Tab), SC-63

Datasheet:: BUD42D-1G.pdf

Description:: TRANS NPN 350V 4A DPAK

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BUD42D-1G from onsemi is a high-speed, high-gain bipolar NPN transistor with integrated antisaturation network and transient voltage suppression capability, rated for 650 V_CEO, 4 A continuous collector current, and 25 W power dissipation in DPAK (Case 369C) package - designed for electronic light ballast circuits requiring fast switching and robust overvoltage handling.

For engineers reviewing the BUD42D-1G datasheet, pinout, applications, or equivalent options, key selection criteria include its 350 V_CEO(sus) sustaining voltage under inductive load, tight dynamic parameter distribution (6 sigma process), built-in freewheeling diode, and thermal resistance of 5.0 °C/W junction-to-case - critical for reliable operation in compact, thermally constrained lighting drivers.

Technical Context

The BUD42D-1G integrates an antisaturation network to minimize storage time and improve turn-off speed, while its monolithic freewheeling diode enables self-contained flyback energy recirculation in inductive switching topologies. Its 650 V_CBO and 650 V_CES breakdown ratings support clamped inductive turn-off at up to 300 V supply with controlled voltage overshoot.

Designed for light ballast applications, it delivers flat DC current gain (h_FE = 8–13 at I_C = 1–2 A), low V_CE(sat) (0.2–1.0 V), and fast switching times - including 4.6–6.55 µs turn-off time with active base drive reversal (I_B1 = 0.4 A, I_B2 = 0.1 A) - enabling high-frequency operation without external snubbers.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO(sus)	350 V - Sustaining voltage under 25 mH inductive load; defines maximum clamped off-state voltage in ballast resonant circuits.
I_C (continuous)	4.0 A - Maximum DC collector current; supports lamp ignition and steady-state operation in 20–60 W fluorescent/LED drivers.
P_D @ T_C = 25°C	25 W - Total device dissipation; requires heatsinking due to R_JC = 5.0 °C/W for thermal management in enclosed fixtures.
V_CE(sat)	0.2–1.0 V - Saturation voltage at I_C = 2 A / I_B = 0.5 A; directly determines conduction loss and thermal rise in switching cycles.
t_off	4.6–6.55 µs - Turn-off time with active base drive reversal; enables >20 kHz operation while maintaining low EMI in magnetic ballasts.
h_FE	8–13 - DC current gain at I_C = 1–2 A; provides stable, predictable base drive requirements across temperature and process variation.
R_JC	5.0 °C/W - Junction-to-case thermal resistance; mandates direct mounting to heatsink for sustained 25 W operation.

Pinout & Package

DPAK (Case 369C) surface-mount package with 4-terminal configuration: two collector pins (pins 2 and 4) for enhanced current handling and thermal path, base (pin 1), and emitter (pin 3).

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control input for transistor switching; accepts 0.2–0.5 A base drive to achieve forced gain (h_FE ≈ 5–10) during saturation.
2	Collector	Main high-voltage, high-current output terminal; electrically tied to pin 4 for parallel current path and lower inductance.
3	Emiter	Reference node for base-emitter bias and freewheeling diode cathode; connects to ground or low-side switch node in half-bridge configurations.
4	Collector	Second collector terminal; shares internal die connection with pin 2 to reduce package inductance and improve thermal spreading.

Key Features

Feature	Design Value
Integrated freewheeling diode	Enables self-contained inductive energy recovery without external diode - reduces component count and PCB area in ballast designs.
Antisaturation network	Minimizes storage time and improves t_off consistency; eliminates need for external Baker clamp in high-reliability lighting systems.
6 sigma process control	Ensures tight lot-to-lot spread in V_CE(sat), h_FE, and t_off - critical for consistent lamp ignition timing and lifetime across production batches.
Transient voltage suppression	Withstands repetitive 300 V clamped inductive spikes without degradation; eliminates need for external TVS in cost-sensitive ballast modules.
Pb-free, RoHS-compliant epoxy	UL 94 V-0 rated at 0.125 in thickness; meets global environmental compliance and flame-retardancy requirements for lighting enclosures.

Applications

Electronic Fluorescent Ballast (EFB)	LED Driver with Inductive Boost
Use Scenario: High-frequency (20–60 kHz) resonant half-bridge driving T5/T8 lamps with instant start and dimming. IC Role / Device Role / Timing Role: Main switching transistor in upper leg of half-bridge; handles 300 V clamped inductive turn-off and lamp ignition surges. Use Value: Integrated diode and antisaturation network eliminate external clamp components, reducing BOM count by 2–3 parts per channel.	Use Scenario: Constant-current boost LED driver for street lighting, operating from 12–48 VDC input with 60–120 V output. IC Role / Device Role / Timing Role: Primary switch in discontinuous conduction mode (DCM) boost converter; sustains 350 V_CEO(sus) during output capacitor charging phase. Use Value: 4.6 µs t_off enables >50 kHz switching, shrinking magnetics size by 30% vs. slower transistors while maintaining thermal margin.
Magnetic Ballast Replacement Module	Compact AC-DC Adapter with PFC
Use Scenario: Retrofit module replacing electromagnetic ballasts in legacy fixtures, accepting 120/230 VAC input. IC Role / Device Role / Timing Role: High-voltage switch in bridgeless PFC front-end; operates in critical conduction mode (CRM) with 650 V_VCBO headroom. Use Value: 650 V_VCBO rating allows direct use without series stacking, simplifying layout and improving reliability over 400 V alternatives.	Use Scenario: Universal-input (85–265 VAC), 30 W adapter with active PFC and flyback secondary for consumer electronics. IC Role / Device Role / Timing Role: PFC switch handling 400 VDC bus; leverages flat h_FE and low V_CE(sat) to maintain >90% efficiency at full load. Use Value: 25 W power rating and 5.0 °C/W R_JC enable single-transistor PFC stage without forced air cooling in sealed enclosures.

Electronic Fluorescent Ballast (EFB)

LED Driver with Inductive Boost

Use Scenario: High-frequency (20–60 kHz) resonant half-bridge driving T5/T8 lamps with instant start and dimming.

IC Role / Device Role / Timing Role: Main switching transistor in upper leg of half-bridge; handles 300 V clamped inductive turn-off and lamp ignition surges.

Use Value: Integrated diode and antisaturation network eliminate external clamp components, reducing BOM count by 2–3 parts per channel.

Use Scenario: Constant-current boost LED driver for street lighting, operating from 12–48 VDC input with 60–120 V output.

IC Role / Device Role / Timing Role: Primary switch in discontinuous conduction mode (DCM) boost converter; sustains 350 V_CEO(sus) during output capacitor charging phase.

Use Value: 4.6 µs t_off enables >50 kHz switching, shrinking magnetics size by 30% vs. slower transistors while maintaining thermal margin.

Magnetic Ballast Replacement Module

Compact AC-DC Adapter with PFC

Use Scenario: Retrofit module replacing electromagnetic ballasts in legacy fixtures, accepting 120/230 VAC input.

IC Role / Device Role / Timing Role: High-voltage switch in bridgeless PFC front-end; operates in critical conduction mode (CRM) with 650 V_VCBO headroom.

Use Value: 650 V_VCBO rating allows direct use without series stacking, simplifying layout and improving reliability over 400 V alternatives.

Use Scenario: Universal-input (85–265 VAC), 30 W adapter with active PFC and flyback secondary for consumer electronics.

IC Role / Device Role / Timing Role: PFC switch handling 400 VDC bus; leverages flat h_FE and low V_CE(sat) to maintain >90% efficiency at full load.

Use Value: 25 W power rating and 5.0 °C/W R_JC enable single-transistor PFC stage without forced air cooling in sealed enclosures.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD42C-1G	Same DPAK package, but lower V_CEO = 300 V and I_C = 3 A; no integrated diode; higher V_CE(sat) (0.5–1.5 V).	Limited to <300 V clamped circuits; requires external freewheeling diode and tighter gate drive design for comparable t_off.	Select when cost is primary constraint and system voltage remains ≤270 V; not suitable for 300 V+ ballast designs.
BUL49D	TO-220 package, 1000 V_VCBO, 8 A I_C, no integrated diode; slower t_off (12–18 µs); R_JC = 2.5 °C/W.	Requires larger heatsink and external diode; better suited for universal input offline SMPS than resonant ballasts.	Choose for higher-power (>60 W), lower-frequency (<15 kHz) applications where thermal mass outweighs switching speed needs.

Compared with MJD42C-1G and BUL49D, the BUD42D-1G uniquely combines integrated diode, 350 V_CEO(sus), and sub-7 µs t_off in DPAK - making it the only drop-in solution for space-constrained, high-frequency electronic ballasts requiring zero external clamp components.

Availability

BUD42D-1G is available at Aetrix Electronics and suitable for electronic fluorescent ballasts, LED boost drivers, and magnetic ballast replacement modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.

Supply support for BUD42D-1G 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, and cloud power applications.

The BUD42D-1G belongs to onsemi's high-voltage bipolar transistor product line, engineered specifically for lighting control systems where fast switching, voltage ruggedness, and integrated protection reduce system complexity and improve reliability.

FAQ

What is the maximum clamped inductive voltage the BUD42D-1G can sustain during turn-off?

The BUD42D-1G is rated for 350 V_CEO(sus) with I_C = 100 mA and L = 25 mH, verified under clamped conditions per datasheet Figure 29. This defines its safe reverse-bias SOA for ballast applications - exceeding this voltage risks second-breakdown failure. The BUD42D-1G must be used with appropriate snubber or clamping circuitry to ensure V_CE stays within this limit during inductive turn-off.

Does the BUD42D-1G require an external freewheeling diode in inductive load circuits?

No - the BUD42D-1G integrates a monolithic freewheeling diode between emitter and collector, confirmed in the "DIODE CHARACTERISTICS" section (VEC = 0.9–1.5 V at I_EC = 1.0 A). This eliminates the need for an external diode in standard flyback configurations, reducing bill-of-materials count and PCB footprint in lighting drivers using the BUD42D-1G.

What is the recommended base drive configuration to achieve optimal switching speed for the BUD42D-1G?

For minimal t_off, the BUD42D-1G datasheet specifies active base drive reversal: I_B1 = 0.4 A turn-on, followed by I_B2 = 0.1 A reverse turn-off current. This configuration achieves t_off = 4.6–6.55 µs. Using only forward base drive (no reversal) increases storage time significantly - the BUD42D-1G performance depends critically on proper base current sequencing per the "SWITCHING CHARACTERISTICS" test conditions.

Can the BUD42D-1G be used in place of the BUD42DT4G in surface-mount assembly?

Yes - both BUD42D-1G and BUD42DT4G use identical DPAK (Case 369C) packaging and share identical electrical specifications. The difference is only in packaging format: BUD42D-1G ships in straight-lead rail (75 units), while BUD42DT4G uses tape-and-reel (2500 units). The BUD42D-1G is fully compatible with SMT reflow processes and occupies the same PCB footprint as the BUD42DT4G.

What thermal derating applies to the BUD42D-1G above 25°C case temperature?

The BUD42D-1G has a thermal derating factor of 0.2 W/°C above T_C = 25°C, per the "MAXIMUM RATINGS" table. At T_C = 75°C, its usable power dissipation drops to 15 W (25 W − 0.2 × 50). This linear derating assumes proper heatsinking - the BUD42D-1G's R_JC = 5.0 °C/W requires direct thermal interface to maintain junction temperature below 150°C under full load.

BUD42D-1G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-252-3, DPAK (2 Leads + Tab), SC-63

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 350 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:: 25 W

Frequency - Transition:: -

Operating Temperature:: -65°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: DPAK

BUD42D-1G FAQ

1.How can I place an order for BUD42D-1G through Aetrix?

Please submit a Request for Quotation (RFQ) for BUD42D-1G 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 BUD42D-1G reliable?

The price and inventory of BUD42D-1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BUD42D-1G is usually 5 days.

3.What payment methods are accepted for BUD42D-1G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BUD42D-1G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BUD42D-1G?

BUD42D-1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BUD42D-1G 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 BUD42D-1G?

For technical support, including BUD42D-1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BUD42D-1G requirements.

6.How does Aetrix verify that BUD42D-1G is sourced from the original manufacturer or authorized distributors?

All BUD42D-1G 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 BUD42D-1G meets industry standards.

7.What is the process for return or replacement of BUD42D-1G?

All BUD42D-1G units undergo pre-shipment inspection (PSI). If there is an issue with BUD42D-1G, 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 BUD42D-1G part is unused and in its original packaging.

Return procedure for BUD42D-1G:

1.Submit a request within 90 days.

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

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