Patent ID: 8890440

Claim:
A controller for controlling power to a light source, said controller comprising: a first sensing pin operable for receiving a first signal indicating an instant current flowing through an energy storage element; a second sensing pin operable for receiving a second signal indicating whether said instant current decreases to a predetermined current level; a driving pin operable for providing a driving signal to a switch to control a current flowing through said light source to a target current level, wherein said driving signal is generated based on one or more signals selected from said first signal and said second signal; an error amplifier operable for generating an error signal based on said first signal and also based on a reference signal indicating said target current level, wherein the output of said error amplifier is coupled to a capacitor, and a power pin operable for receiving a voltage to power said controller, wherein said controller determines whether said light source is in a short circuit condition according to said voltage.