Patent ID: 7952892

Claim:
A DC converter comprising: a first switch and a first diode coupled between first and second input terminals for supply of an input voltage, the first switch being coupled between the first input terminal and a first junction, the first diode being coupled between the first junction and the second input terminal; a signal source coupled to supply a control signal to the first switch for switching the first switch on and off with a substantially constant duty ratio in successive switching cycles; an LLC converter circuit coupled to the first junction for providing an LLC output, and an LLC control circuit responsive to the LLC output for controlling a variable frequency oscillator for determining a switching cycle frequency of the control signal to regulate the LLC output; and a plurality of flyback or forward DC converter circuits, each comprising: a respective second switch and a respective second diode coupled between the first and second input terminals, the second diode being coupled between the first input terminal and a second junction, the second switch being coupled between the second junction and the second input terminal; a respective transformer having a primary winding coupled between the first junction and the second junction, the arrangement being such that the primary winding is coupled to the first input terminal through the first switch and to the second input terminal through the second switch; a respective rectifier circuit connected to a secondary winding of the transformer for producing a respective DC output; and a respective control unit responsive to the DC output for controlling the second switch with a respective variable duty ratio to regulate the DC output and provide a respective independently regulated DC output, the second switch being switched in each switching cycle to be on during a least a portion of the switching cycle in which the first switch is on and then switched off in each switching cycle while the first switch is on.