Patent ID: 8004256
Filing Date: 2011-08-23
Classification: H02M

Abstract:
1. A current limiting circuit for a boost converter comprising: a control circuit configured to detect an output voltage and switch a main switch including a transistor so that the output voltage becomes a target value; a voltage divider circuit including two transistors of the same type as that of the main switch, the two transistors being connected in series; a reference transistor of the same type as that of the main switch and having a gate terminal connected to a bias voltage; a constant current source connected to a drain terminal of the reference transistor and configured to flow a constant current; and a comparator configured to compare a voltage at a voltage division point of the voltage divider circuit with a product of an on-resistance of the reference transistor and the current of the constant current source, wherein the voltage divider circuit includes the comparator outputs a current limit signal to block output of the control circuit when a signal indicating a result of the comparison reaches a predetermined level.