CONTROLLING A SWITCHED MODE POWER SUPPLY WITH MAXIMISED POWER EFFICIENCY

摘要

A control circuit operable to generate a control signal (D) to control the duty cycle of a switched mode power supply (100), The control circuit comprises an. input terminal (205) for receiving a signal indicative of an input voltage (Vln) of the switched mode power supply (100), and a reference signal generator (210) operable to generate, in dependence upon the received signal, a reference signal (VR) that is a function of the input voltage (Vln). The control circuit further comprises an error signal generator (230) arranged to receive a signal indicative of an output voltage (Vout) of the switched mode power supply (100) and operable to generate an error signal (VE) based on the reference signal (VR) and based on the output voltage (Vout). The control circuit also includes a low pass filter (225) connected between the input terminal (205) and the error signal generator (230), in series with the reference signal generator (210), and a duty cycle control signal generator (250) operable to generate the control signal (D) to control the duty cycle of the switched mode power supply (100) in dependence upon the error signal (VE).