Control methods and apparatuses providing a holding current for a TRIAC dimmer are disclosed. A control method is suitable for a power controller powered by an operation power source. A high-voltage device in the power controller is connected between the operation power source and an input power source, from which the high-voltage device drains a conduction current. An operation voltage of the operation power source is detected, and, during a startup procedure, the conduction current is forwarded to charge the operation power source. A detected voltage representing an input voltage of the input power source is provided, and if the detected voltage is below a setting voltage, the conduction current is forwarded to a ground line instead of charging the operation power source.