A DESATURATION DETECTION CIRCUIT FOR USE BETWEEN THE DESATURATION DETECTION INPUT OF AN OPTOCOUPLER AND THE OUTPUT OF A POWER SWITCHING DEVICE

摘要

A desaturation detection circuit for use between the desaturation detection input of an optocoupler and the output of a power switching device, the desaturation detection circuit comprising:a threshold setting element having an input and an output, the input for connection to the output of a power switching device via one or more diode(s), the threshold setting element being arranged to set a threshold voltage at the input at which the threshold setting element will provide an output at the output of the threshold setting element when the input voltage is exceeded, and a detector having an input connected to the output of the threshold setting element and an output connectable to a desaturation detection input of an optocoupler, the detector being arranged to detect an output at the output of the threshold setting element and in response to provide a control signal at the output of the detector for the desaturation detection input to trigger a desaturation routine in the optocoupler. A method of operating a desaturation detection circuit is also described comprising: monitoring the voltage input to the desaturation detection circuit, determining whether the voltage input- to the desaturation detection circuit is greater than or equal to a threshold voltage above a desaturation voltage and, when the voltage input to the desaturation detection circuit is greater than or equal to a threshold voltage above a desaturation voltage, outputting a control signal to trigger a desaturation routine.