STMicroelectronics Offers ESBT Series Bipolar Transistors

STMicroelectronics Inc. (ST, Geneva, Switzerland) introduced a family of hybrid emitter-switched, bipolar transistors (EBST®) 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. The new ESBT Series represents a breakthrough in the area of high-voltage, high-switching frequency applications, and resolves the power supply designer’s dilemma of choosing either bipolar junction transistors (BJT), characterised by low conduction losses and slow switching speeds, or MOSFETs, with their fast switching speeds and high conduction losses.

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 130 kHz can be achieved under hard 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 benefit is a high-voltage capability of up to 1.7 kV, which allows designs to operate with a higher flyback voltage and a higher duty cycle. This 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, the STC05DE150, and the STC08DE150, which feature breakdown voltages of 1.7 kV, 1.5 kV, and 1.5 kV, respectively, and on-resistances of 0.55 Ω, 0.17 Ω, and 0.11 Ω, respectively. In comparison, 1,500 V power MOSFETs typically exhibit on-resistances in the range 5 Ω to 9 Ω. All three devices feature a Vcs(sat) value of 0.9 V, minimizing conduction losses, while the absence of tail currents also minimizes turn-off losses. As a result, the new ESBT family enables cooler and more reliable operation in all power supply applications from 30 W to 150 W.

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, maximizing the system reliability in harsh industrial environments. The STC03DE150, STC03DE170, and STC08DE150 are available in production volumes, with pricing for 100-piece sample quantities of $3.10, $3.30, and $3.60, respectively.