Masters Theses

Date of Award

12-1982

Degree Type

Thesis

Degree Name

Master of Science

Major

Electrical Engineering

Major Professor

T. V. Blalock

Committee Members

E. J. Kennedy, Robert E. Bodenheimer

Abstract

The difficulty in building circuitry for operation in the temperature range of 200°C is compounded when reliability is also critical since the rates of most failure mechanisms seen in electronic devices increase dramatically with temperature. A maximally reliable system must be kept as simple as possible. This requirement combined with the generally poor characteristics of semiconductor devices at elevated temperatures indeed make the design of reliable high-temperature circuits nontrivial. In this thesis a low-power DC-to-DC conversion system designed for low component count and operation up to 230°C is discussed and analyzed in detail. The particular focus is the clock arid duty-cycle-control circuitry required, of which two designs are proposed. The first of these worked well at 230°C for over 200 hours except for an oscillator latch-up problem seen to occur at 230°C. The second design was one intended to overcome the latch-up problem but was not evaluated at 230°C. It did, however, show promise during bench evaluation. Both designs, although intended for use at 230°C, will work at 25°C also where they may be useful in other DC-to-DC conversion systems.

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