Patent ID: 7903006

Claim:
An automatic power control system for an optical disc drive to control the power of laser beam, the optical disc drive comprising a laser diode for receiving a control signal to generate a laser beam; and a photodetector for detecting the laser beam to generate an analog input signal; the automatic power control system, comprising: an analog-to-digital converter, converting the analog input signal into digital data; a down sampling circuit, coupled to the analog-to-digital converter, comprising: a down sampler, receiving a predetermined amount of digital data to generate representation data; and a controller, coupled to the down sampler, disabling the down sampler when the digital data is invalid, and resetting the down sampler when the amount of digital data equals or exceeds a predetermined count; a comparator, coupled to the down sampling circuit, comparing the representation data with predetermined target data to generate error data; and a digital-to-analog converter, coupled to the comparator, converting the error data to analog to generate the control signal.