Negative n-epi biasing sensing and high side gate driver output spurious turn-on prevention due to n-epi p-sub diode conduction during n-epi negative transient voltage

Abstract

A high-side driver in a driver circuit for driving a half-bridge stage having high- and low-side power switching devices series connected at a switched node, the high-side driver driving the high-side power switching device. The high-side driver including first and second complementary switched MOSFET series connected at a high-side node, driving the high-side power switching device, one of the MOSFETs having a parasitic bipolar transistor formed between the substrate, an N+ epitaxial region connected to the high-side driver supply voltage and the switched node, with the parasitic transistor having a base electrode formed by the N+ epitaxial region, an emitter electrode formed by the substrate and a collector electrode formed by the switched node, such that if a transient voltage that is negative with respect to the substrate is present at the high-side driver supply voltage, the parasitic transistor will conduct a short circuit current between the switched node and the substrate; a first circuit for controlling the conduction of the first and second MOSFETs to switch the high-side switching device ON and OFF; a diffusion in the N+ epitaxial region in which a terminal connected to the switched node is provided by the diffusion forming the collector of the parasitic transistor; and a second circuit coupled to the diffusion for sensing the high-side driver supply voltage at the epitaxial region and providing a signal to the first circuit to prevent turn-ON of the high-side power switching device.