Power converter controller with branch switch

A controller for a power converter configured to control a turn ON and turn OFF of a power switch to deliver energy between an input and an output of the power converter, the controller comprising:

• a driver configured to provide a drive signal to control the power switch, wherein the power switch includes a first switch and a second switch;
• a terminal configured to be coupled to a capacitance, wherein the terminal is coupled to receive operating power for the controller;
• a branch switch coupled to the second switch;
• a branch control configured to turn ON the branch switch in response to a comparison of a voltage at the terminal with a reference to conduct a branch current to the terminal, wherein the branch current is at least a first portion of a drain current conducted by the first switch;
• and
• a regulator configured to sense the branch current, wherein the regulator and driver are configured to regulate the branch current by keeping the second switch at least partially ON during an on-time of the branch switch or by turning the second switch at least partially ON in response to the branch current reaching a branch current threshold, wherein the branch current threshold is less than or equal to the drain current conducted by the first switch.