Power converter with plural regulated outputs

A four-quadrant switching amplifier comprising:

• a current mode pulse width modulator responsive to a control voltage, a sensed current signal, and a clock signal for providing a pulse width modulated output signal;
• a power stage comprising a power transformer, a current sensing transformer, and first and second switches, a first winding of the current sensing transformer being coupled to the pulse width modulator for supplying the sensed current signal thereto, the first switch, a first winding of the power transformer, and a second winding of the current sensing transformer being coupled in series and to a power source for supplying current to the power transformer when the first switch is closed, a second winding of the power transformer and the second switch being coupled in series and to the power source for returning current from the power transformer when the second switch is closed, third windings of the power and current sensing transformers being coupled in series for providing a positive voltage on a positive voltage output line of the power stage, and fourth windings of the power and current sensing transformers being coupled in series for providing a negative voltage on a negative voltage output line of the power stage;
• a plurality of output circuits each comprising an output voltage line, two controlled switches for coupling the output voltage line selectively to the positive and negative output voltage lines of the power stage, means for smoothing an output voltage on the output voltage line, and a potential divider for deriving a feedback voltage representative of the smoothed output voltage;
• and
• control and logic circuitry responsive to the clock signal, the output signal of the pulse width modulator, a plurality of input voltages each associated with a respective output circuit, and the respective feedback voltages for, sequentially and cyclically for the plurality of output circuits, controlling the switches of each output circuit, synchronously supplying as the control voltage for the pulse width modulator a voltage derived from the respective input and feedback voltages for the associated output circuit, and controlling the switches of the power stage, whereby the output voltage of each output circuit is an amplified version of the associated input voltage.

A power converter comprising:

• a current mode pulse width modulator responsive to a clock signal and having control and current sensing inputs and an output;
• a power stage including a switch controlled by the output of the pulse width modulator, a power transformer having a primary winding, coupled in series with the switch, and a secondary winding, and a current sensing resistor connected in series with the switch and the primary winding and coupled to the current sensing input of the pulse width modulator;
• a plurality of N output circuits each including smoothing means, a switch for coupling the smoothing means to the secondary winding of the power transformer to produce a respective output voltage from the smoothing means, and a potential divider for providing a feedback voltage dependent upon the output voltage;
• means for frequency dividing the clock signal of the pulse width modulator by N to produce a frequency divided clock signal;
• means for controlling the switches of the output circuits sequentially and cyclically in dependence upon the frequency divided clock signal;
• and
• selector means responsive to the frequency divided clock signal for supplying the feedback voltages to the control input of the pulse width modulator sequentially and cyclically in synchronism with the control of the switches of the output circuits to provide for regulation of each output voltage.