Systems and methods for DC-to-DC converter control

1. A method for controlling a number of phases that are active in a multiphase direct-current-to-direct-current (DC-to-DC) converter, comprising:

filtering a first current signal representing a magnitude of current processed by the multiphase DC-to-DC converter to generate a second current signal different from the first current signal;

using a first comparator, comparing the second current signal to a first threshold value;

deactivating one or more phases of the multiphase DC-to-DC converter in response to the second current signal falling below the first threshold value;

using a second comparator, comparing the first current signal lo a second threshold value, the second threshold value being greater than the first threshold value, the second comparator responding to a change in load current more quickly than the first comparator;

activating one or more phases of the multiphase DC-to-DC converter in response to the first current signal rising above the second threshold value;

preventing one or more phases of the DC-to-DC converter from being deactivated within a predetermined time period of the one or more phases of the DC-to-DC converter being activated; and

overriding a signal to deactivate one or more phases of the multiphase DC-to-DC converter in response to the first current signal rising above the second threshold value.

2. The method of claim 1 , further comprising adjusting at least one of the first threshold value and the second threshold value according to a number of phases of the multiphase DC-to-DC converter that are operating.

3. The method of claim 1 , wherein the step of activating one or more phases of the multiphase DC-to-DC converter comprises simultaneously activating a plurality of phases of the multiphase DC-to-DC converter.

4. The method of claim 3 , wherein the step of deactivating one or more phases of the multiphase DC-to-DC converter comprises simultaneously deactivating a plurality of phases of the multiphase DC-to-DC converter.

5. The method of claim 1 , further comprising:

comparing the second current signal to a third threshold value that is less than the first threshold value;

deactivating one or more phases of the multiphase DC-to-DC converter in response to the second current signal falling below the third threshold value; and

comparing the first current signal to a fourth threshold value that is greater than the second threshold value; and

activating one or more phases of the multiphase DC-to-DC converter in response to the first current signal rising above the fourth threshold value.

6. A controller for a multiphase direct-current-to-direct-current (DC-to-DC) converter, comprising:

a low-pass filter configured to filter a first current signal representing a magnitude of current processed by the multiphase DC-to-DC converter lo generate a second current signal different from the first current signal;

a first comparator configured to compare the second current signal to a first threshold value;

a second comparator configured to compare the first current signal to a second threshold value, the second threshold value being greater than the first threshold value, the first comparator and the second comparator being configured such that the second comparator responds to a change in load current more quickly than the first comparator; and

phase enable logic configured to:

deactivate one or more phases of the multiphase DC-to-DC converter in response to the second current signal falling below the first threshold value, and

activate one or more phases of the multiphase DC-to-DC converter in response to the first current signal rising above the second threshold value,

prevent one or more phases of the DC-to-DC converter from being deactivated within a predetermined time period of the one or more phases of the DC-to-DC converter being activated, and

override a signal to deactivate one or more phases of the multiphase DC-to-DC converter in response to the first current signal rising above the second threshold value.

7. The controller of claim 6 , further comprising a programmable threshold generator configured to generate at least the first and second threshold values.

8. The controller of claim 7 , wherein the programmable threshold generator is further configured to adjust at least one of the first threshold value and the second threshold value according to a number of phases of the multiphase DC-to-DC converter that are operating.

9. The controller of claim 6 , wherein the phase enable logic is further configured to simultaneously deactivate a plurality of phases of the DC-to-DC converter in response to the second current signal falling below the first threshold value.

10. The controller of claim 9 , wherein the phase enable logic is further configured to simultaneously activate a plurality of phases of the multiphase DC-to-DC converter in response to the first current signal rising above the second threshold value.

11. The controller of claim 6 , further comprising:

a third comparator configured to compare the second current signal to a third threshold value that is less than the first threshold value; and

a fourth comparator configured to compare the first current signal to a fourth threshold value that is greater than the second threshold value,

where the phase enable logic is further configured to:

deactivate one or more phases of the multiphase DC-to-DC converter in response to the second current signal falling below the third threshold value, and

activate one or more phases of the multiphase DC-to-DC converter in response to the first current signal rising above the fourth threshold value.