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Emitter-Switched Bipolar Transistors from STMicroelectronics Set New Standard for Power-Supply Applications


Hybrid BJT/MOSFETs deliver ‘best of both worlds’ performance.

Geneva, October 5, 2005 - STMicroelectronics (NYSE: STM), a technology and market leader in power transistors, has introduced a family of hybrid Emitter-Switched Bipolar Transistors (EBST®) particularly suitable for industrial three-phase auxiliary power supplies and Single-Ended Primary Inductance Converters (SEPIC) used as power factor pre-regulators in industrial lighting applications. By offering the industry’s best combination of low forward voltage drop, high blocking voltage and fast switching speed, the new ESBT series represents a breakthrough in the area of high voltage, high switching frequency applications.

The new ESBT family resolves the power supply designer’s dilemma of choosing either bipolar junction transistors (BJT), characterised by low conduction losses but slow switching speeds, or MOSFETs, with their fast switching speeds but high conduction losses. Instead, by incorporating a BJT and MOSFET connected in a cascode configuration and housed in a single package, the new devices retain the benefits of each approach while eliminating the disadvantages e.g. conduction losses are comparable to those of a single BJT while switching frequencies over 130kHz can be achieved under hard (snubberless) switching conditions, which the devices can safely handle thanks to the square reverse bias safe operating area resulting from its cascode configuration and dedicated bipolar technology

Another significant benefit of the new devices is a high voltage capability of up to 1.7kV, which allows designs to operate with a higher flyback voltage and, consequently, a higher duty cycle. This, in turn, allows the power supply to handle higher powers or to operate within a wider range of input voltage.

Members of the new family include the STC03DE170, STC05DE150 and the STC08DE150, which feature breakdown voltages of 1.7, 1.5 and 1.5kV, respectively, and on-resistances of 0.55, 0.17 and 0.11 Ohms, respectively. In comparison, 1500V power MOSFETs typically exhibit on-resistances in the range 5-9 Ohms. All three devices feature a Vcs(sat) value of 0.9V, minimising conduction losses, while the absence of tail currents also minimises turn-off losses. As a result, the new ESBT family enables cooler and more reliable operation in all power supply applications from 30W to 150W.

All of the new devices are housed in a custom-designed four-lead TO-247 package featuring a lateral collector pin to increase the clearance between high voltage and low voltage pins, maximising the system reliability in harsh industrial environments. The STC03DE150, STC03DE170 and STC08DE150 are available in production volumes, with pricing for sample (100pcs) quantities of $3.10, $3.30 and $3.60, respectively.

Through its Application Laboratories and Competence Centres, ST provides comprehensive support for the new ESBT family, including application notes and reference design boards.

Further information is also avaialble at:

About STMicroelectronics
STMicroelectronics is a global leader in developing and delivering semiconductor solutions across the spectrum of microelectronics applications. An unrivalled combination of silicon and system expertise, manufacturing strength, Intellectual Property (IP) portfolio and strategic partners positions the Company at the forefront of System-on-Chip (SoC) technology and its products play a key role in enabling today’s convergence markets. The Company’s shares are traded on the New York Stock Exchange, on Euronext Paris and on the Milan Stock Exchange. In 2004, the Company’s net revenues were $8.76 billion and net earnings were $601 million. Further information on ST can be found at


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