Adaptive reactivation of phases deactivated by phase-shedding in multi-phase voltage regulators
In a multi-phase power supply voltage regulator functioning at a nominal switching frequency, one or more phases are kept off for optimizing energy efficiency at relatively low load conditions. Reactivation of stand-by phases in response to a load increase transient is made more efficiently by exploiting information already present in the output voltage control loop. The technique comprises a) deriving from the control loop information on the equivalent nominal switching frequency given by the product of the nominal switching frequency by the number of active phases; b) updating at every beat of a clock signal the instantaneous value of the equivalent switching frequency; c) determining the band of equivalent switching frequency values to which the instantaneous value belongs; d) logically combining the equivalent switching frequency information with a determined band of output current level, for switching on one or more stand-by phases in response to a load increase transient.
1. A method, comprising:
adaptively switching off one or more phases of a multi-phase power supply voltage regulator to increase energy efficiency at relatively low load conditions of operation, the voltage regulator being configured to function at a nominal switching frequency, the switching off leaving active a number of active phases of the voltage regulator;
determining a band of current output levels, among a plurality of bands, corresponding to the number of active phases; and
keeping off the multi-phase power supply voltage regulator for optimizing energy efficiency at relatively low load conditions of operation, based on the determining, the adaptively switching including:
deriving information on an equivalent switching frequency equal to a product of said nominal switching frequency by the number of phases that are active;
updating at every beat of a clock signal an instantaneous value of the equivalent switching frequency;
determining a band of equivalent switching frequency values, among a plurality of bands, to which said instantaneous value of the equivalent switching frequency belongs; and
logically combining said band of equivalent switching frequency values and said band of output current levels, for switching on one or more stand-by phases in response to a load increase transient.
2. The method of claim 1 , wherein:
determining the band of output current levels among the plurality of current level bands includes comparing them with thresholds of separation between adjacent bands, with a non-null hysteresis.
3. The method of claim 1 , wherein the deriving, updating, and determining are implemented with analog circuits.
4. The method of claim 1 , wherein the deriving, updating, and determining are implemented with digital circuits.
5. The method of claim 1 , wherein from an instant of switching on of said one or more stand-by phases, their switching off is inhibited for a programmed delay time.
6. A multi-phase power supply voltage regulator configured to function at a nominal switching frequency, comprising:
a plural number of phases;
a variable frequency controller configured to set the nominal switching frequency; and
a phase switching controller configured to switch off one or more of the phases to optimize energy efficiency at relatively low load conditions of operation, the controller including:
a sensor configured to sense an instantaneous current absorbed by a load;
a first comparator configured to determine a band of output current levels among a plurality of bands corresponding to the number of phases of the multi-phase power supply voltage regulator;
a frequency detector configured to detect an equivalent switching frequency given by a product of said nominal switching frequency by a number of the phases that are active, the frequency detector being configured to update the detected equivalent switching frequency at every beat of a clock signal;
a second comparator configured to compare the updated detected equivalent switching frequency with a plurality of thresholds and determine a band of equivalent switching frequency values, among said plurality of thresholds, to which the updated detected equivalent switching frequency belongs; and
a combinatory logic circuit block configured to logically combine said determined band of output current levels and the determined band of equivalent switching frequency values, and switch on one or more stand-by phases of the plurality of phases in response to a load increase transient.
7. The multi-phase power supply voltage regulator of claim 6 , wherein said first and second comparators each have a non-null hysteresis.
8. The multi-phase power supply voltage regulator of claim 6 , wherein said frequency detector and second comparator are analog circuits.
9. The multi-phase power supply voltage regulator of claim 6 , wherein said frequency detector and second comparator are digital circuits.
10. The multi-phase power supply voltage regulator of claim 6 , further comprising a delay block configured to inhibit, for a programmed delay time starting from an instant of switching on of said one or more stand-by phases, the switching off of said one or more stand-by phases.
11. A control system configured to control a multi-phase power supply voltage regulator that includes a plural number of phases;
a variable frequency controller configured to set a nominal switching frequency of the multi-phase power supply voltage regulator; and
a phase switching controller configured to switch off one or more of the phases to optimize energy efficiency at relatively low load conditions of operation, the controller including:
a sensor configured to sense an instantaneous current absorbed by a load;
a first comparator configured to determine a band of output current levels among a plurality of bands corresponding to the number of phases of the multi-phase power supply voltage regulator;
a frequency detector configured to detect an equivalent switching frequency given by a product of said nominal switching frequency by a number of the phases that are active, the frequency detector being configured to update the detected equivalent switching frequency at every beat of a clock signal;
a second comparator configured to compare the updated detected equivalent switching frequency with a plurality of thresholds and determine a band of equivalent switching frequency values, among said plurality of thresholds, to which the updated detected equivalent switching frequency belongs; and
a combinatory logic circuit block configured to logically combine said determined band of output current levels and the determined band of equivalent switching frequency values, and switch on one or more stand-by phases of the plurality of phases in response to a load increase transient.
12. The control system of claim 11 , wherein said first and second comparators each have a non-null hysteresis.
13. The control system of claim 11 , wherein said frequency detector and second comparator are analog circuits.
14. The control system of claim 11 , wherein said frequency detector and second comparator are digital circuits.
15. The control system of claim 11 , further comprising a delay block configured to inhibit, for a programmed delay time starting from an instant of switching on of said one or more stand-by phases, the switching off of said one or more stand-by phases.