STMicroelectronics BUL3P5

Overview

BUL3P5 from STMicroelectronics is a medium-voltage, fast-switching PNP power transistor in TO-220 package, rated for V_CES = −500 V, I_C = −3 A, and P_TOT = 60 W at T_C = 25°C. It features cellular emitter structure with planar edge termination, optimized for electronic ballasts in compact fluorescent lamps and high-frequency (H.F.) ballast voltage FED systems, where it operates complementarily with BUL3N7.

For engineers reviewing the BUL3P5 datasheet, BUL3P5 pinout, BUL3P5 application, or BUL3P5 equivalent, key selection criteria include its −400 V V_CEO(sus), 100 ns rise time (resistive load), 450 ns storage time (inductive load), R_thJ-case = 2.08 °C/W, and −1.3 V V_BE(sat) at I_C = −2 A / I_B = −0.4 A - all critical for high-efficiency, thermally constrained lighting driver designs.

Technical Context

The BUL3P5 employs Multi-Epitaxial Planar technology to achieve high switching speed while sustaining medium voltage operation. Its cellular emitter layout and planar edge termination jointly widen the Reverse Biased Safe Operating Area (RBSOA) without compromising dynamic performance.

It is specifically engineered for complementary push-pull operation in HF electronic ballasts, where precise matching with BUL3N7 enables balanced switching transitions and reduced cross-conduction losses under inductive load conditions (e.g., lamp choke + resonant capacitor).

Key Specifications

Pinout & Package

Package: TO-220 (3-lead, straight lead, insulated tab). Mounting surface is electrically connected to collector (Pin 2). Standard JEDEC TO-220 mechanical dimensions per datasheet page 7/10.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BU508AF and MJE13009, BUL3P5 offers optimal balance of −500 V blocking, 100 ns switching speed, and −0.5 V saturation voltage - uniquely aligned with the thermal and dynamic constraints of compact fluorescent electronic ballasts.

Availability

BUL3P5 is available at Aetrix Electronics and suitable for compact fluorescent lamp ballasts, high-frequency voltage FED drivers, and industrial lighting control modules requiring stable component supply and legacy product continuity support.

Supply support for BUL3P5 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, and analog ICs for industrial, automotive, and consumer markets.

The BUL3P5 belongs to ST's high-voltage bipolar transistor family designed explicitly for energy-efficient lighting drivers - emphasizing rugged switching, tight parameter distribution, and compatibility with complementary NPN counterparts like BUL3N7.

FAQ

Is BUL3P5 still in active production?

No - STMicroelectronics has marked BUL3P5 as obsolete (per datasheet rev.2, Dec 2005). However, Aetrix Electronics maintains legacy inventory and offers controlled-life supply with full traceability, including date-code verification and original packaging documentation for ongoing production support.

Can BUL3P5 be used as a direct replacement for BUL3P4?

No - BUL3P4 has V_CES = −400 V and lower I_C (−2 A), while BUL3P5 is rated for −500 V and −3 A. Substituting BUL3P5 for BUL3P4 is safe electrically, but replacing BUL3P5 with BUL3P4 risks overvoltage failure under transient conditions in 230 VAC-fed ballasts.

What is the recommended base drive configuration?

Use active base pull-down (e.g., NPN transistor or logic gate) to ensure rapid turn-off. For I_C = −2 A, apply I_B ≤ −0.4 A with 100 ns rise/fall edges. Base resistor must limit peak I_B to ≤ −3 A (IBM rating); typical value is 10 Ω with −12 V drive for reliable saturation and minimal storage time.

Does BUL3P5 require a heatsink in 30 W CFL ballast operation?

Yes - at 30 W output with 60 W P_TOT derating, junction temperature exceeds 150°C without thermal management. With R_thJ-case = 2.08 °C/W and R_thCase-amb ≈ 25 °C/W (typical TO-220 on 25 cm² copper pad), a minimum 10 cm² aluminum heatsink is required to maintain T_J ≤ 125°C at 40°C ambient.