Geneva - STMicroelectronics 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.