Integrated monolithic over-voltage protection circuit with adjustable threshold voltage

Abstract

A new over-voltage protection circuit has been developed. In this protection circuit, the dissipative part is monolithically integrated in the same protected power chip with almost no additional technologic process or modifications. This monolithic integration takes advantage of main switch cooling system to extract over heating. At the same time it minimizes interconnections between the protected transistor and its protection system. This gives high performance results in term of over voltage protection time response and thermal power removal capabilities. In addition to that, the design of this protection circuit enables to adjust the protection voltage threshold. This is useful for series transistor associations in high voltage applications. The design aims to improve the performance and to reduce the cost and the volume of the protection circuit. The design has been validated with practical results.