Patent ID: 7583068

Claim:
A method for a voltage-controlled device or a current-controlled device, the method comprising: providing a selection unit to receive a control signal to select one of a first reference voltage and a second reference voltage as a reference voltage, the first reference voltage and the second reference voltage being either a low reference voltage or a high reference voltage; providing a control circuit to compare the reference voltage with a feedback signal; adjusting a controlled analog signal in reference to a difference between the reference voltage and the feedback signal until the feedback signal converges to the reference voltage, wherein the controlled analog signal being a square wave signal possesses a certain duty cycle, the feedback signal reflecting the duty cycle, the feedback signal and the reference voltage adjust the duty cycle till the feedback signal converges to the reference voltage and the duty cycle converges to a predefined reference mark; providing the controlled analog signal appropriate to drive the current-controlled device when the control is set a first state; providing the controlled analog signal appropriate to drive the voltage-controlled device when the control is set a second state; wherein the feedback signal is obtained from a load being driven by the controlled analog signal, the load being either one of the voltage-controlled device or the current-controlled device; and when the power is detected to have been applied on, sending reset signals to the selection unit and the controlling circuit, respectively.