Diode Effects Bring Liefetime Risks to Series Resistors

Inhalt:
The limited pulse power capability of resistors is often underestimated in cases of bootstrap and desaturation detection (DESAT) circuits. This contribution investigates the behavior of high voltage diodes, series-connected to a resistor and operated with fast transient reverse voltages. The evaluation is taking simulation and measurements into account. Since the critical cases of operation are different within bootstrapping and DESAT circuits, both cases are explained here in detail. It is worked out that capacitive pulse currents can have a severe lifetime impact on resistors which are connected in series to such diodes.