Switch control device with zero-cross point estimation by edge detection, power supply device comprising the same, and switch control method with zero-cross point estimation by edge detection

A switch control method of a power switch, comprising:

• generating a power voltage by using an input-terminal voltage at an input terminal of the power switch;
• estimating a zero cross-point when the input-terminal voltage is zero voltage by using an edge of the power voltage;
• and
• generating a reference signal synchronized to the input-terminal voltage by using the estimated zero cross-point.

A power supply device, comprising:

• a power switch inputted with full-wave current rectification voltage generated by rectifying an AC input;
• and
• a switch control device for controlling a switching operation of the power switch,
• wherein the switch control device includes:
• a self power voltage biasing circuit generating a power voltage required to operate the switch control device by using the full-wave rectification voltage;
• a reference signal generator detecting a zero cross-point when the full-wave rectification voltage is zero voltage by using an edge of the power voltage and generating a reference signal synchronized to the full-wave rectification voltage of the power switch by using the detected zero cross-point;
• and
• a PWM controller controlling the switching operation of the power switch by comparing the reference signal with current that flows on the power switch.