Light source driving circuit with over-voltage protection

摘要

An over-voltage protection circuit clamps an output voltage of a light source driving circuit. The over-voltage protection circuit includes a transistor and two resistors. When the load of the light source driving circuit is broken, the over-voltage protection circuit utilizes the current generated from the error amplifier in order to enter the transistor into saturation region and accordingly generates a fixed gate voltage. The fixed gate voltage is utilized to clamp the output voltage of the light source driving circuit through the two resistors.