Switching power supply, controller therefor and improvements thereof

A controller for a switching power supply, the controller comprising:

• a power factor correction controller configured to control a power factor correction circuit arrangement to generate a regulated DC output voltage for provision to a resonant switching converter having a resonant switching frequency, wherein the controller for the switching power supply is configured to adjust a level of the regulated DC output voltage according to a level of power provided to the resonant switching converter in order to maintain a switching frequency of the resonant switching converter at or near the resonant frequency, wherein the power factor correction circuit arrangement is configured to generate an error signal wherein the error signal is representative of a difference between a current target level for the regulated DC output voltage and a monitored level of the DC output voltage;
• and
• a detector circuit arrangement coupled to the power factor correction controller and configured to detect a level of power drawn by the resonant switching converter in order to adjust the level of the regulated DC output, wherein the controller for the switching power supply is configured to generate the error signal by a transconductance amplifier and to use the error signal to modulate switching of the power factor correction circuit arrangement and further wherein the controller for the switching power supply is configured adjust to the level of the regulated DC output voltage by activating a current source coupled to the transconductance amplifier.