Low-power dc-to-dc converter having high overvoltage protection

Abstract

A dc-to-dc converter is provided with overvoltage protection circuitry while still providing normal output voltage. Such overvoltage protection circuitry does not require resetting. The overvoltage protection circuitry includes a first switching device connected between the input bridge and a dc output voltage bus and further includes an overvoltage current path. The overvoltage current path includes a complementary switching device in series with Zener diode circuitry having a predetermined breakdown voltage, and further has a transition current path. The first switching device is closed for nominal input voltage and is open for overvoltages. When the input voltage exceeds the Zener diode breakdown voltage, the transition current path conducts current. When the threshold voltage of the complementary switching device is exceeded, the complementary switching device turns on and conducts current through the overvoltage current path. After the overvoltage transient condition subsides and the input voltage decreases back to the nominal range, the complementary switching device turns off, and normal converter operation resumes.

Dependencies are inferred from the claim text.