onsemi BUL45D2

Overview

BUL45D2 from onsemi is a high-speed, high-gain NPN bipolar power transistor with integrated collector-emitter freewheeling diode and built-in antisaturation network. It delivers 5 A continuous collector current, 400 V collector-emitter sustaining voltage, and guaranteed storage time ≤900 ns - optimized for electronic lighting ballasts and PFC circuits.

For engineers reviewing the BUL45D2 datasheet, pinout, applications, or equivalent options, key selection criteria include dynamic saturation voltage (VCE(dsat) ≤0.4 V at 3 s), low base drive requirement (IB = 0.4 A for IC = 2 A), integrated diode forward voltage (VEC = 1.04 V @ 1 A), and TO-220-3 package thermal resistance (RJC = 1.65 °C/W).

Technical Context

The BUL45D2 employs H2BIP (High-Speed High-Gain Bipolar) architecture to minimize lot-to-lot spread in storage time (±150 ns), eliminating need for hFE window guarantees. Its integrated collector-emitter diode enables self-contained flyback operation in inductive switching topologies.

Dynamic saturation voltage is characterized at two time points (1 s and 3 s after IB rise), supporting precise timing control in high-frequency ballast drivers. The "6 Sigma" manufacturing process ensures tight parameter spreads across VCE(sat), hFE, and switching times under both resistive and inductive load conditions.

Key Specifications

Pinout & Package

Package: TO-220-3 (Case 221A, Style 1), with metal tab electrically connected to collector (pin 2 and pin 4). Mounting surface requires electrical isolation unless collector is referenced to chassis ground.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN bipolar power transistor applications.

Compared with STN1050 and MJE13009, the BUL45D2 uniquely combines integrated diode functionality, ±150 ns storage time guarantee, and validated dynamic saturation voltage - making it irreplaceable in high-reliability lighting ballasts where timing predictability and component count reduction are mandatory.

Availability

BUL45D2 is available at Aetrix Electronics and suitable for electronic lighting ballasts, active PFC stages, and inductive load drivers requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for BUL45D2 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 markets.

The BUL45D2 belongs to onsemi's H2BIP high-speed bipolar transistor family, engineered specifically for lighting ballast and PFC applications demanding tight dynamic parameter control and integrated diode functionality.

FAQ

What is the maximum continuous collector current rating for the BUL45D2?

The BUL45D2 is rated for 5 A continuous collector current at case temperature TC = 25 °C. Derating applies above 25 °C at 0.6 W/°C, and peak current capability reaches 10 A under pulse conditions (5 ms, ≤10% duty cycle). This rating is validated across the full −65 °C to +150 °C operating range and supports high-duty-cycle lamp driver applications.

Does the BUL45D2 include an integrated diode, and what are its electrical characteristics?

Yes, the BUL45D2 integrates a collector-emitter freewheeling diode. Its forward voltage is 1.04 V at 1 A and 25 °C, 0.85 V at 0.4 A and 25 °C, and 0.7 V at 1 A and 125 °C. The diode is monolithically fabricated within the same die and shares thermal behavior with the transistor junction - enabling matched thermal tracking in high-frequency switching.

How does the BUL45D2 achieve guaranteed storage time performance?

The BUL45D2 uses H2BIP (High-Speed High-Gain Bipolar) structure with optimized doping profiles and antisaturation network to limit minority carrier lifetime. This yields guaranteed storage time of ≤900 ns (typical 720 ns) with ±150 ns lot-to-lot spread - verified per datasheet Figure 15–20 and Table 1 under standardized inductive load test conditions (Vclamp = 300 V, L = 200 µH).

What is the thermal resistance from junction to case (RJC) for the BUL45D2, and how does it impact heatsink design?

The BUL45D2 has a maximum RJC of 1.65 °C/W in its TO-220-3 package. At full 75 W dissipation, this results in ≤124 °C junction-to-case temperature rise - allowing use of compact extruded aluminum heatsinks (e.g., 50 × 50 × 25 mm) without forced air. The metal tab is electrically connected to collector (pins 2 and 4), so electrical isolation is required unless collector is at chassis potential.

Is the BUL45D2 pin-compatible with other TO-220 NPN transistors like the MJE13009?

No - while both use TO-220-3 packages, the BUL45D2 has dual collector terminals (pins 2 and 4), whereas the MJE13009 has single collector (pin 2). Pin 4 on the BUL45D2 is not NC; it is internally bonded to pin 2 and must be connected to the same net. Direct replacement requires PCB layout revision to accommodate the second collector pad and verify thermal/mechanical mounting compatibility.