Control with hysteresis of an electronic device using a pulse-width modulated signal

1. An electronic device comprising:

a switched circuit having an output designed to deliver an output voltage, and controlled by a control signal with two pulse-width modulated states;

a first hysteresis comparator, with a first low-voltage threshold and a first high-voltage threshold higher than said first low-voltage threshold, designed to generate the control signal depending on a comparison between the output voltage and the first low-voltage threshold and the first high-voltage threshold;

at least a second hysteresis comparator, with a second low-voltage threshold and a second high-voltage threshold higher than said second low-voltage threshold, designed to generate the control signal depending on a comparison between the output voltage and the second low-voltage threshold and the second high-voltage threshold, a difference between the second high-voltage threshold and the second low-voltage threshold being less than a difference between the first high-voltage threshold and the first low-voltage threshold; and

a control unit ( 34 ) adapted to measure a control signal frequency, and for enabling either the first hysteresis comparator or the second hysteresis comparator depending on the control signal measured frequency, the first hysteresis comparator being enabled for relatively control signal low frequencies, and the second hysteresis comparator being enabled for relatively control signal high frequencies.

2. The electronic device as claimed in claim 1 , in which, the first hysteresis comparator being enabled, the control unit is adapted to disable the first hysteresis comparator and for enabling the second hysteresis comparator when the control signal frequency becomes higher than a first frequency threshold.

3. The electronic device as claimed in claim 1 , in which, the second hysteresis comparator being enabled, the control unit is adapted to disable the second hysteresis comparator and to enable the first hysteresis comparator when the control signal frequency becomes lower than a second frequency threshold, higher than the first frequency threshold.

4. The electronic device as claimed in claim 1 , in which the second low-voltage threshold is higher than the first low-voltage threshold, and the second high-voltage threshold is lower than the first high-voltage threshold.

5. The electronic device as claimed in claim 1 , in which the control unit comprises a pulse counter, designed to deliver a number of pulses of the control signal counted per unit of time as a measurement of the frequency of said control signal.

6. A switched-mode power supply comprising at least one device for chopping an input voltage, wherein the chopping device comprises an electronic device as claimed in claim 1 whose output voltage corresponds to a supply voltage delivered by the switched-mode power supply.

7. The switched-mode power supply as claimed in claim 6 , in which the device for chopping the input voltage has the structure of a DC-DC voltage converter, of the step-down voltage converter, the step-up voltage converter, or the step-down/step-up voltage converter type.

8. The switched-mode power supply as claimed in claim 6 , in which the device for chopping the input voltage comprises a MOSFET or IGBT power transistor.

9. The switched-mode power supply as claimed in claim 7 , in which the device for chopping the input voltage comprises a MOSFET or IGBT power transistor.

10. A switching method for a circuit designed to generate an output voltage starting from a control signal with two pulse-width modulated states, comprising:

measuring control signal frequency; and,

enabling a first hysteresis comparator or a second hysteresis comparator depending on the measured control signal frequency, in order to generate the control signal,

in which:

the first hysteresis comparator having a first low-voltage threshold and a first high-voltage threshold higher than said first low-voltage threshold, and being adapted to generate the control signal depending on a the comparison between the output voltage, the first low-voltage threshold and the first high-voltage threshold, is enabled for relatively low frequencies of the control signal; and,

the second hysteresis comparator having a second low-voltage threshold and a second high-voltage threshold higher than said second low-voltage threshold, and being adapted to generate the control signal depending on comparison between the output voltage, the second low-voltage threshold and the second high-voltage threshold, is enabled for relatively high frequencies of the control signal,

and in which:

a difference between the second high-voltage threshold and the second low-voltage threshold is lower than a difference between the first high-voltage threshold and the first low-voltage threshold.

11. The electronic device as claimed in claim 2 , in which, the second hysteresis comparator being enabled, the control unit is adapted to disable the second hysteresis comparator and to enable the first hysteresis comparator when the control signal frequency becomes lower than a second frequency threshold, higher than the first frequency threshold.

12. The electronic device as claimed in claim 2 , in which the second low-voltage threshold is higher than the first low-voltage threshold, and the second high-voltage threshold is lower than the first high-voltage threshold.

13. The electronic device as claimed in claim 3 , in which the second low-voltage threshold is higher than the first low-voltage threshold, and the second high-voltage threshold is lower than the first high-voltage threshold.

14. The electronic device as claimed in claim 2 , in which the control unit comprises a pulse counter, designed to deliver a number of pulses of the control signal counted per unit of time as a measurement of the frequency of said control signal.

15. The electronic device as claimed in claim 3 , in which the control unit comprises a pulse counter, designed to deliver a number of pulses of the control signal counted per unit of time as a measurement of the frequency of said control signal.

16. The electronic device as claimed in claim 4 , in which the control unit comprises a pulse counter, designed to deliver a number of pulses of the control signal counted per unit of time as a measurement of the frequency of said control signal.

17. A switched-mode power supply comprising at least one device for chopping an input voltage, wherein the chopping device comprises an electronic device as claimed in claim 2 , whose output voltage corresponds to a supply voltage delivered by the switched-mode power supply.

18. A switched-mode power supply comprising at least one device for chopping an input voltage, wherein the chopping device comprises an electronic device as claimed in claim 3 , whose output voltage corresponds to a supply voltage delivered by the switched-mode power supply.

19. A switched-mode power supply comprising at least one device for chopping an input voltage, wherein the chopping device comprises an electronic device as claimed in claim 4 , whose output voltage corresponds to a supply voltage delivered by the switched-mode power supply.

20. A switched-mode power supply comprising at least one device for chopping an input voltage, wherein the chopping device comprises an electronic device as claimed in claim 5 , whose output voltage corresponds to a supply voltage delivered by the switched-mode power supply.