Switched power stage and a method for controlling the latter

1. A method of generating a regulated voltage, comprising:

generating an output voltage from a high voltage source;

providing an inductor having a first terminal and a second terminal linked to a low voltage source by a capacitor, the second inductor terminal supplying the output voltage to a load;

generating command signals as a function of a high voltage supplied by the high voltage source and the output voltage, to reduce a difference between the output voltage and a reference voltage lower than the high voltage; and

connecting the first inductor terminal exclusively either to the high input voltage or the low voltage or to the inductor second terminal, as a function of the command signals;

wherein when the output voltage is lower than the reference voltage reduced by a tolerance voltage, the first inductor terminal is connected to the high voltage source for a clock period in accordance with the command signals, and wherein when the output voltage is greater than the reference voltage reduced by a tolerance voltage and lower than the reference voltage, the first inductor terminal is connected to the high voltage source for a first period, and connected to the low voltage source for a second period adjacent to the first period in accordance with the command signals;

wherein the first period is the clock period multiplied by a first positive integer number, and the second period is the clock period multiplied by a second positive integer number, the first and second integer numbers being defined such that the ratio of the first integer number to a sum of the first and second integer numbers is lower or equal to the ratio of the output voltage to the high voltage.

2. The method according to claim 1 , further comprising connecting the first inductor terminal to the second inductor terminal for a clock period, when the output voltage is greater than the reference voltage.

3. The method according to claim 1 , comprising connecting the first inductor terminal to the low voltage source for a clock period, when a current in the inductor is greater than a current threshold value.

4. A switched power stage providing a regulated output voltage, the power stage comprising:

an inductor having a first inductor terminal and a second inductor terminal forming an output of the power stage,

a capacitor linking the second inductor terminal to the low voltage source,

a switching device linking the first inductor terminal exclusively either to a high voltage source, or to a low voltage source, or to the second inductor terminal, and

a control circuit for generating command signals controlling the switching device as a function of a high voltage supplied by the high voltage source and the output voltage, to reduce a difference between the output voltage and a reference voltage lower than the high voltage, with the control circuit configured to control the switching device to:

connect the first inductor terminal to the high voltage source for a clock period, when the output voltage is lower than the reference voltage reduced by a tolerance voltage, and

generate a current pulse in the inductor by connecting the first inductor terminal to the high voltage source for a first period, and connecting the first inductor terminal to the low voltage source for a second period adjacent to the first period, when the output voltage is lower than the reference voltage and greater than the reference voltage reduced by the tolerance voltage.

5. The power stage according to claim 4 , wherein the control circuit is configured to control the switching device to generate a current pulse in the inductor by successively connecting the first inductor terminal to the high voltage source for a first period and to the low voltage source for a second period adjacent to the first period, when the output voltage is lower than the reference voltage.

6. The power stage according to claim 5 , wherein the current pulse generated in the inductor has a triangular shape.

7. The power stage according to claim 5 , wherein the control circuit comprises a voltage generator for generating the reference voltage, and a comparator for comparing the output voltage with the reference voltage.

8. The power stage according to claim 5 , wherein the first period is determined by multiplying a clock period by a first positive integer number, and the second period is determined by multiplying the clock period by a second positive integer number, the control circuit comprising a lookup table defining the first and second integer numbers as a function of a first ratio of the output voltage to the high voltage such that a second ratio of the first integer number to a sum of the first and second integer numbers is lower or equal to the first ratio.

9. The power stage according to claim 4 , wherein the control circuit is configured to control the switching device to connect the first inductor terminal to the second inductor terminal for a clock period, when the output voltage is greater than the reference voltage.

10. The power stage according to claim 4 , further comprising a voltage generator for generating the reference voltage and the reference voltage reduced by the tolerance voltage, a first voltage comparator for comparing the output voltage with the reference voltage, and a second voltage comparator for comparing the output voltage with the reference voltage reduced by the tolerance voltage.

11. The power stage according to claim 4 , further comprising a current comparator for comparing a current in the inductor with a current threshold value, the control circuit being configured to control the switching device to connect the first inductor terminal to the low voltage source for a clock period, when the current in the inductor is greater than the current threshold value.