Power supply circuit for charging a bootstrap capacitor

摘要

A switching power supply circuit is provided for capacitor charging, wherein a power device is coupled to a terminal node of a capacitor to be charged and has a control terminal coupled to the output of an associated drive circuit. This circuit includes a second power element being associated with the first power device, coupled to said terminal node, and provided with a control terminal which is connected directly to the output of respective drive logic. The second power element is driven to turn on when a voltage below a predetermined minimum is present at the capacitor, thereby pulling the voltage at the terminal node to ground and further charging the capacitor.