CONTROLLING A SWITCHED MODE POWER SUPPLY WITH MAXIMISED POWER EFFICIENCY

摘要

To generate a control signal for controlling the duty cycle of a switched mode power supply (SMPS), a control circuit is provided which advantageously allows the duty cycle to be varied in dependence upon the input voltage of the SMPS and in dependence upon the output voltage of the SMPS. This allows more accurate control of the duty cycle to maintain maximal power efficiency whilst compensating for voltage transients. In particular, a control circuit has an input voltage reference voltage generator arranged to receive a signal indicative of an input voltage of the SMPS and is arranged to generate a reference signal dependent upon the input voltage. An error signal generator of the control circuit is arranged to receive a signal indicative of an output voltage of the SMPS and arranged to generate an error signal based on the reference signal generated by the input reference voltage generator and based on the output voltage of the SMPS. A duty cycle control signal generator of the control circuit is arranged to generate a control signal, to control the duty cycle of the SMPS, in dependence upon the error signal.