Patent ID: 6958583

Claim:
An AC voltage control circuit for use in a power saving device for a discharge lamp, wherein the AC voltage control circuit comprises: a first voltage terminal supplied with the voltage of an output stage of the power saving device; a current terminal supplied with the current of the power saving device; a first comparator for comparing the input voltage of the first voltage terminal and a predetermined target output voltage; a second comparator for comparing the input voltage of the first voltage terminal and a predetermined permissible voltage; a third comparator for comparing the input current of the current terminal and a predetermined permissible current; a central processing unit connected to the first, second and third comparators, so that the central processing unit controls the output voltage of the power saving device according to the result of voltage comparison of the first comparator and controls the power saving device to be protected from abnormal voltage and current according to the results of the voltage comparison of the second comparator and the current comparison of the third comparator; a switching means for converting the output voltage of the power saving device under the control of the central processing unit; and a timer connected to the central processing unit.