Apparatus for controlling bleed switch, power supply, and method for driving power supply

A power supply, comprising:

• a TRIAC dimmer;
• and
• an AC-DC converter connected to the TRIAC dimmer, wherein the AC-DC converter comprises:
• a transformer;
• a power switch coupled to the transformer;
• a bleed switch;
• and
• a bleed switch controller for turning off the bleed switch in a first time duration and turning on the bleed switch in a second time duration, wherein magnitude of a current of the power switch in the first time duration is larger than magnitude of a current of the power switch in the second time duration.

A method of driving a power supply of which consumption power is controlled by a TRIAC dimmer, wherein the power supply comprises a bleed switch, the method comprising:

• generating a first control signal having a first level in a first time duration and having a second level in a second time duration;
• generating a second control signal by using the first control signal;
• and
• providing the second control signal to the bleed switch,
• wherein the bleed switch is turned off in the first time duration, and
• wherein the bleed switch is turned on in the second time duration, wherein magnitude of a current of a power switch in the first time duration is larger than magnitude of a current of the power switch in the second time duration, the power switch being coupled to a transformer of an AC-DC converter.