US Patent 9479065 Controller supply terminal boosting

A power conversion device includes a power switch a first main terminal coupled to a higher potential portion, a second main terminal coupled to a lower potential portion, and a tap coupled to the first main terminal to provide a current for charging a supply terminal capacitor. A controller is coupled to a control terminal of the power switch to control switching of the power switch to produce a regulated output. A supply terminal is to be coupled to a supply terminal capacitor to store a charge for supplying power to at least some of the components of the controller. A voltage regulator is coupled to regulate the charge stored and a potential on the supply terminal capacitor. The current for charging the supply terminal capacitor is selectively drawn from the tap of the power switch in response to the supply terminal capacitor being below a threshold.