DC-DC converter with floating capacitors

1. A DC-DC power converter comprising:

a switch capacitor power converter coupled to a power converter input, a power converter output, and comprising a switchable capacitor;

a controller coupled to the switch capacitor power converter, wherein the controller is configured to generate two non-overlapping clock signals having different durations, vary a non-overlapping time duration dependent on the voltage and/or current value of at least one of the power converter output, a reference value, and the power converter input, and operation of the switch capacitor power converter is frozen by a pair of multiplexers during the non-overlapping time duration between the two non-overlapping clock signals, wherein each multiplexer receives a respective clock signal of different duration as an input signal.

2. The DC-DC power converter of claim 1 , wherein the controller is coupled to the power converter input, the power converter output, and a reference input configured to receive the reference value, and the switch capacitor power converter is controllable by the two non-overlapping clock signals.

3. The DC-DC power converter of claim 1 , wherein the controller comprises:

an error detector, wherein the error detector comprises a first input configured to receive the reference value, a second input coupled to the power converter output;

a non-overlapping clock generator coupled to an output of the error detector and configured to vary the clock frequency dependent on the difference between the output voltage and the reference value; and

a control module coupled to an output of the error detector, wherein the control module is configured to generate a modulation control signal for the non-overlapping clock generator.

4. The DC-DC power converter of claim 1 , wherein the controller comprises a timing reference generator.

5. The DC-DC power converter of claim 1 , wherein the controller is configured to increase the non-overlapping time duration in response to at least one of a decrease in output current supplied by the DC-DC power converter, a decrease in the reference value, and an increase in the input voltage of the DC-DC converter.

6. The DC-DC power converter of claim 1 , wherein the controller is configured to decrease the non-overlapping time duration in response to at least one of an increase in the output current supplied by the DC-DC power converter, an increase in the reference value, and a decrease in the input voltage of the DC-DC converter.

7. The DC-DC power converter of claim 1 , further comprising:

an output capacitor coupled to the power converter output.

8. The DC-DC power converter of claim 1 , wherein all floating capacitors of the switch capacitor power converter are disconnected by the pair of multiplexers during the non-overlapping time duration.

9. The DC-DC power converter of claim 3 , wherein each multiplexer of the pair of multiplexers has a first input coupled to a respective output of the non-overlapping clock generator, a second input operably coupled to an off-voltage level, and a control input coupled to the controller, wherein the controller is configured to modulate the non-overlapping time duration by selecting between the first and second inputs in response to a time reference signal.

10. The DC-DC power converter of claim 4 , wherein the timing reference generator is configured to generate a time reference signal equal to half of a nominal switching period.

11. The DC-DC power converter of claim 4 , wherein the timing reference generator is configured to generate a time reference signal dependent on at least one of a charge time and a discharge time of the switchable capacitor.

12. The DC-DC power converter of claim 4 , wherein the timing reference generator is coupled to an oscillator.

13. A method of controlling a DC-DC power converter comprising a switch capacitor power converter having a switchable capacitor, the method comprising:

providing two non-overlapping clocks having different durations to the switch capacitor power converter; and

modulating the non-overlapping time duration of the non-overlapping clocks in dependence on the voltage and/or the current of at least one of the power converter output, the power converter input, and a reference value, wherein operation of the switch capacitor power converter is frozen by a pair of multiplexers during the non-overlapping time duration between the two non-overlapping clocks, wherein each multiplexer receives a respective clock signal of different duration as an input signal.

14. The method of claim 13 , further comprising:

decreasing the non-overlapping time duration in response to at least one of an increase of the output current provided by the DC-DC power converter, an increase in the reference value, and a decrease of the input voltage.

15. The method of claim 13 , further comprising:

increasing the non-overlapping time duration in response to at least one of a decrease in the output current provided by the DC-DC power converter, a decrease in the reference value, and an increase of the input voltage.

16. The method of claim 13 , wherein modulating the non-overlapping time duration further comprises:

generating a time reference signal dependent on at least one of the charge time and discharge time of the switchable capacitor.

17. The method of claim 13 , wherein all floating capacitors of the switch capacitor power converter are disconnected by the pair of multiplexers during the non-overlapping time duration.