STMicroelectronics BUX98A

Overview

BUX98A from STMicroelectronics is a high-voltage, high-current NPN power transistor in TO-3 metal package, designed for industrial switching and linear applications operating from single- or three-phase mains. It delivers 1000 V VCER/VCES, 30 A continuous collector current, 250 W total power dissipation at Tc = 25 °C, and fast switching with ton = 1 µs, ts = 3 µs, tf = 0.8 µs - used in high-efficiency AC-DC converters and motor drive output stages.

For engineers reviewing the BUX98A datasheet, BUX98A pinout, BUX98A application, or BUX98A equivalent, key selection criteria include its 450 V VCEO rating, 200 °C max junction temperature, 0.7 °C/W thermal resistance, and robust safe operating area under inductive load conditions.

Technical Context

This multi-epitaxial mesa NPN transistor operates with base-emitter forward bias control and supports high-energy pulse handling via ICP = 80 A (tp ≤ 20 µs). Its sustaining voltage VCER(sus) = 1000 V at IC = 1 A with RBE = 10 Ω confirms ruggedness in snubberless inductive switching.

The device exhibits hFE ≥ 20 at IC = 16 A, VCE = 5 V, Tj = 25 °C, and maintains VCE(sat) ≤ 1.5 V at IC = 16 A / IB = 3.2 A - enabling low conduction loss in high-power linear regulators and phase-control circuits.

Key Specifications

Pinout & Package

TO-3 metal package with isolated collector case (Case = Pin 2), emitter (Pin 1), and base (Pin 3) terminals. Mounting hole centered on case for heatsink attachment; electrically isolated collector enables common-source layout in high-side switch designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BUW96 and 2SC5387, BUX98A provides superior voltage headroom (1000 V), higher current capacity (30 A), and lower thermal resistance (0.7 °C/W), making it uniquely suited for high-reliability, high-power industrial switching where derating margin and thermal management are critical.

Availability

BUX98A is available at Aetrix Electronics and suitable for industrial AC-DC converters, three-phase motor drives, and linear regulator pass devices requiring stable component supply across extended production lifecycles.

Supply support for BUX98A 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, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

BUX98A belongs to ST's high-voltage bipolar power transistor product line, engineered specifically for ruggedized industrial mains-connected equipment demanding high dV/dt immunity, wide SOA, and long-term thermal stability.

FAQ

What is the maximum safe operating voltage for BUX98A in a grounded-emitter configuration?

In grounded-emitter mode with IB = 0, BUX98A's VCEO rating is 450 V - this is the absolute maximum DC collector-emitter voltage before breakdown. Exceeding this value risks avalanche failure, even with current limiting. For 690 VAC rectified applications, the device must be used in emitter-follower or common-base configurations where VCER = 1000 V applies.

Can BUX98A be used without a heatsink at 10 A continuous collector current?

No. At IC = 10 A and VCE(sat) ≈ 1.2 V, power dissipation is ~12 W. With Rthj-case = 0.7 °C/W and ambient at 50 °C, junction temperature would exceed 125 °C even with minimal case-to-ambient resistance. A heatsink with Rthc-a ≤ 2.5 °C/W is mandatory for reliable operation at any sustained current above 2 A.

What base drive requirements does BUX98A demand for full saturation at 24 A collector current?

To achieve VCE(sat) ≤ 5 V at IC = 24 A, the datasheet specifies IB = 5 A. This requires a low-impedance, current-limited driver capable of delivering 5 A peak with <100 ns rise time. A 1 Ω base resistor is insufficient; active base drive with complementary BJT or MOSFET buffer stages is necessary to avoid second breakdown during transition.

Is BUX98A compliant with modern RoHS and REACH requirements?

Yes - per ST's ECOPACK® documentation, BUX98A uses lead-free second-level interconnect and complies with RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. The TO-3 metal package carries the ECOPACK marking on both device body and inner box label, confirming environmental compliance per JEDEC JESD97.