Buck-Converter Design for Power in Plus 275°C Environments

Abstract

The design and development of a dc to dc buck converter capable of operating up to 275°C is presented. The control circuitry design is based on the vee-square (V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) control mechanism. The system converts a raw dc input voltage in the range of 15 V to 25 V to a stepped-down and filtered output voltage in the range of 1.5 V to 18 V. A custom designed user programmable control circuitry is implemented on the low leakage, radiation tolerant silicon-on-insulator technology. Silicon carbide junction field effect transistors (JFETs) are used as power switches to sustain extreme operating temperature. The system is prototyped on the aluminum nitride substrate to meet packaging requirements. Design considerations for the planar transformer coupled gate drive are specifically addressed. The system performance is studied based on a 20 V to 3.3 V prototype converter. The demonstrated system has potential market in extreme environment applications like deep space explorations, down-hole geothermal and deep gas reservoir management, etc.