Method for managing a plurality of hysteretic DC-DC buck converters and corresponding DC-DC buck converter

• US 9,712,060 B2
• Filed: 03/31/2016
• Issued: 07/18/2017
• Est. Priority Date: 09/22/2015
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Pulici, Paolo, Mazzucco, Massimo
• Primary Examiner(s): Pham, Emily P
• Application Number:
  US15/087,082
• Publication Number:
  US 20170085180A1
• Time in Patent Office: 474 Days
• CPC Class Codes: G05F 1/46 wherein the variable actually regulated by the final control device is dc G05F1/625 takes precedence
• CPC Class Codes: H02M 1/0025 Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
• CPC Class Codes: H02M 1/008 Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel

Abstract

A method manages hysteretic DC-DC buck converters each including a hysteretic comparator operating according to a respective hysteresis window. The method includes, in a given converter, verifying if a respective feedback voltage reaches a lower threshold in order to enter a switch-on period of the converter, The method comprises: while the verifying indicates that the lower threshold is not reached, detecting if another converter has entered a respective switch on period and, in the affirmative, entering a hysteresis voltage adjustment procedure, include increasing by a given amount the amplitude of the hysteresis window of the given converter by reducing the lower threshold of the hysteresis window.

Claims

1. A method, comprising:

managing a plurality of hysteretic DC-DC buck converters, each including a hysteretic comparator operating according to a respective hysteresis window, for each of the hysteretic DC-DC buck converters the managing including;

verifying if a respective feedback voltage of the hysteretic DC-DC buck converter reaches a lower threshold in order to enter a switch-on period of the hysteretic DC-DC buck converter,

detecting if an other hysteretic DC-DC buck converter in said plurality of hysteretic DC-DC buck converters has entered a respective switch-on period,

in response to detecting that the other hysteretic DC-DC buck converter in said plurality of hysteretic DC-DC buck converters has entered the respective switch-on period, entering a hysteresis voltage adjustment procedure that includes increasing an amplitude of the hysteresis window of the hysteretic DC-DC buck converter.

2. The method according to claim 1, wherein increasing the amplitude of the hysteresis window of the hysteretic DC-DC buck converter includes reducing a lower threshold of the hysteresis window of the hysteretic DC-DC buck converter.

3. The method according to claim 2, wherein said hysteresis voltage adjustment procedure includes for each hysteretic DC-DC buck converter, after increasing the amplitude of the hysteresis window:

verifying if the feedback voltage of the hysteretic DC-DC buck converter now reaches the lower threshold, and

increasing a higher threshold of the hysteresis window in response to verifying that the feedback voltage of the hysteretic DC-DC buck converter has reached the lower threshold.

4. The method according to claim 3, wherein for each hysteretic DC-DC buck converter:

subsequently verifying if the switch-on period of the other hysteretic DC-DC buck converter is complete; and

restoring the lower threshold of the hysteretic DC-DC buck converter in response to subsequently verifying that the switch-on period of the other hysteretic DC-DC buck converter is complete.

5. The method according to claim 3, wherein for each hysteretic DC-DC buck converter:

subsequently verifying if the switch-on period of the other hysteretic DC-DC buck converter is complete; and

restoring the lower threshold in response to verifying that the feedback voltage of the hysteretic DC-DC buck converter has not reached the lower threshold and subsequently verifying that the switch-on period of the other hysteretic DC-DC buck converter is complete.

6. The method according to claim 2, wherein for each hysteretic DC-DC buck converter, said hysteresis voltage adjustment procedure includes:

detecting if a further converter, different from said other converter, has entered a respective switch-on period; and

performing a further instance of the hysteresis voltage adjustment procedure in response to detecting that the further converter has entered the respective switch-on period.

7. The method according to claim 6, wherein, for each hysteretic DC-DC buck converter, performing the further instance of the hysteresis voltage adjustment procedure includes increasing a higher threshold of the hysteresis window of the hysteretic DC-DC buck converter.

8. The method according to claim 1, wherein the hysteretic DC-DC buck converters create plural output voltages, respectively, and respectively provide the plural output voltages to respective loads.

9. A method, comprising:

managing a plurality of hysteretic DC-DC buck converters, each including a hysteretic comparator operating according to a respective hysteresis window, for each of the hysteretic DC-DC buck converters the managing including;

verifying if a respective feedback voltage of the hysteretic DC-DC buck converter reaches a lower threshold in order to enter a switch-on period of the hysteretic DC-DC buck converter,

detecting if an other hysteretic DC-DC buck converter in said plurality of hysteretic DC-DC buck converters has entered a respective switch-on period,

in response to detecting that the other hysteretic DC-DC buck converter in said plurality of hysteretic DC-DC buck converters has entered the respective switch-on period, changing an amplitude of the hysteresis window of the hysteretic DC-DC buck converter.

10. The method according to claim 9, wherein changing the amplitude of the hysteresis window of the hysteretic DC-DC buck converter includes changing a lower threshold of the hysteresis window of the hysteretic DC-DC buck converter.

11. The method according to claim 10, wherein said hysteresis voltage adjustment procedure includes for each hysteretic DC-DC buck converter, after changing the amplitude of the hysteresis window:

verifying if the feedback voltage of the hysteretic DC-DC buck converter now reaches the lower threshold, and

changing a higher threshold of the hysteresis window in response to verifying that the feedback voltage of the hysteretic DC-DC buck converter has reached the lower threshold.

12. The method according to claim 11, wherein for each hysteretic DC-DC buck converter:

subsequently verifying if the switch-on period of the other hysteretic DC-DC buck converter is complete; and

restoring the lower threshold of the hysteretic DC-DC buck converter in response to subsequently verifying that the switch-on period of the other hysteretic DC-DC buck converter is complete.

13. The method according to claim 11, wherein for each hysteretic DC-DC buck converter:

subsequently verifying if the switch-on period of the other hysteretic DC-DC buck converter is complete; and

restoring the lower threshold in response to verifying that the feedback voltage of the hysteretic DC-DC buck converter has not reached the lower threshold and subsequently verifying that the switch-on period of the other hysteretic DC-DC buck converter is complete.

14. The method according to claim 10, wherein for each hysteretic DC-DC buck converter, said hysteresis voltage adjustment procedure includes:

detecting if a further converter, different from said other converter, has entered a respective switch-on period; and

performing a further instance of the hysteresis voltage adjustment procedure in response to detecting that the further converter has entered the respective switch-on period.

15. The method according to claim 14, wherein, for each hysteretic DC-DC buck converter, performing the further instance of the hysteresis voltage adjustment procedure includes changing a higher threshold of the hysteresis window of the hysteretic DC-DC buck converter.

16. The method according to claim 9, wherein the hysteretic DC-DC buck converters provide a common supply current to a common load.

17. A DC-DC buck converter system, comprising:

a plurality of hysteretic DC-DC buck converters each including a hysteretic comparator configured to operate according to a respective hysteresis window; and

a plurality of control circuits coupled to the hysteretic DC-DC buck converters, respectively, each control circuit being configured to manage the respective hysteretic DC-DC buck converter by a method that includes;

verifying if a respective feedback voltage of the hysteretic DC-DC buck converter reaches a lower threshold in order to enter a switch-on period of the hysteretic DC-DC buck converter,

detecting if an other hysteretic DC-DC buck converter in said plurality of hysteretic DC-DC buck converters has entered a respective switch-on period,

in response to detecting that the other hysteretic DC-DC buck converter in said plurality of hysteretic DC-DC buck converters has entered the respective switch-on period, entering a hysteresis voltage adjustment procedure that increases an amplitude of the hysteresis window of the hysteretic DC-DC buck converter.

18. The DC-DC buck converter system according to claim 17, wherein each control circuit is configured to increase the amplitude of the hysteresis window of the hysteretic DC-DC buck converter by reducing a lower threshold of the hysteresis window of the hysteretic DC-DC buck converter.

19. The DC-DC buck converter system according to claim 18, wherein each control circuit comprises:

an actuation circuit configured to increase the amplitude of the hysteresis window of the respective hysteretic DC-DC buck converter; and

a synchronizing logic circuit to detect reaching of the switch on period of the other converter in said plurality of converters, said synchronizing logic circuit being configured to command the actuation circuit to increase the amplitude of the hysteresis window of the respective hysteretic DC-DC buck converter.

20. The DC-DC buck converter system according to claim 19, wherein said synchronizing logic circuit is configured to receive PWM signals of the plurality of converters, detect the reaching of the switch on period of the other converter from said PWM signals, and issue activation signals that cause the actuation circuit to increase said amplitude of the hysteresis window of the respective hysteretic DC-DC buck converter from a normal value to an enlarged value.

21. The DC-DC buck converter according to claim 17, wherein said plurality of hysteretic DC-DC buck converters is arranged on a same chip or die.