Voltage regulator circuit with undershoot compensation

1 . A power management system, comprising:

a voltage regulator circuit; and

a detection circuit configured to:

set the voltage regulator circuit in a valley current control mode of operation during a first steady state current drawn by one or more electronic circuits coupled to the voltage regulator circuit;

set the voltage regulator circuit in a peak current control mode of operation during a transient current between the first steady state current and a second steady state current drawn by the one or more electronic circuits, in response to a load voltage provided by the voltage regulator circuit falling below a predetermined voltage level; and

set the voltage regulator circuit in the valley current control mode of operation after the second steady state current has been reached.

2 . The power management system of claim 1 , further comprising:

a current detection circuit coupled to an output of the voltage regulator circuit and configured to monitor the first and second steady state currents and the load voltage.

3 . The power management system of claim 1 , wherein the voltage regulator circuit comprises a DC-DC converter having an inductor, and wherein the detection circuit is further configured to send a control signal to the voltage regulator circuit to transition the voltage regulator circuit from the peak current control mode of operation to the valley current control mode of operation, in response to a current flowing through the inductor reaching an upper value of a limit current.

4 . The power management system of claim 3 , wherein the limit current is at a fixed current level during the valley current control mode of operation.

5 . The power management system of claim 3 , wherein the limit current increases as the transient current increases during the peak current control mode of operation.

6 . The power management system of claim 3 , wherein the limit current is at a fixed current level after the second steady state current has been reached.

7 . The power management system of claim 1 , wherein the voltage regulator circuit comprises:

a first switching transistor;

a second switching transistor;

an inductor with a first terminal and a second terminal, wherein the first terminal is electrically connected to the first and second switching transistors and the second terminal is electrically connected to the one or more electronic circuits; and

a control circuit coupled to the detection circuit and configured to activate and deactivate the first and second switching transistors during the valley current control mode of operation and the peak current control mode of operation.

8 . The power management system of claim 7 , wherein the control circuit is further configured to:

activate and deactivate the first and second switching transistors at a substantially constant frequency during the valley current control mode of operation; and

deactivate the second switching transistor and pass a power supply source to the one or more electronic circuits through the first switching transistor during the peak current control mode of operation.

9 . A device, comprising:

one or more electronic circuits; and

a power management system coupled to the one or more electronic circuits and comprising:

a plurality of voltage regulator circuits; and

a current control detection circuit configured to:

set the plurality of voltage regulator circuits in a valley current control mode of operation during a first steady state current drawn by the one or more electronic circuits, wherein the plurality of voltage regulator circuits operate at a substantially constant switching frequency and are phased to be active at spaced intervals during the valley current control mode of operation;

set the plurality of voltage regulator circuits in a peak current control mode of operation during a transient current between the first steady state current and a second steady state current drawn by the one or more electronic circuits, in response to a load voltage provided by the plurality of voltage regulator circuits falling below a predetermined voltage level, wherein the plurality of voltage regulator circuits pass a power supply source to the one or more electronic circuits during the peak current control mode of operation; and

set the plurality of voltage regulator circuits in the valley current control mode of operation after the second steady state current has been reached, wherein the plurality of voltage regulator circuits operate at the substantially constant switching frequency and are phased to be active at the spaced intervals during the valley current control mode of operation.

10 . The device of claim 9 , wherein the power management system further comprises a current detection circuit coupled to outputs of the plurality of voltage regulator circuits and configured to monitor the first and second steady state currents and the load voltage.

11 . The device of claim 9 , wherein each of the plurality of voltage regulator circuits comprises a DC-DC converter having an inductor, and wherein the current control detection circuit is further configured to send a control signal to the plurality of voltage regulator circuits to transition the plurality of voltage regulator circuits from the peak current control mode of operation to the valley current control mode of operation, in response to a current flowing through the inductors reaching an upper value of a limit current.

12 . The device of claim 11 , wherein the limit current is at a fixed current level during the valley current control mode of operation.

13 . The device of claim 11 , wherein the limit current increases as the transient current increases during the peak current control mode of operation.

14 . The device of claim 11 , wherein the limit current is at a fixed current level after the second steady state current has been reached.

15 . The device of claim 9 , wherein each of the plurality of voltage regulator circuits comprises:

a first switching transistor;

a second switching transistor;

an inductor with a first terminal and a second terminal, wherein the first terminal is electrically connected to the first and second switching transistors and the second terminal is electrically connected to the one or more electronic circuits; and

a switch controller coupled to the current control detection circuit and configured to activate and deactivate the first and second switching transistors during the valley current control mode of operation and the peak current control mode of operation.

16 . The device of claim 15 , wherein the switch controller is further configured to:

activate and deactivate the first and second switching transistors at a substantially constant frequency during the valley current control mode of operation; and

deactivate the second switching transistor and pass the power supply source to the one or more electronic circuits through the first switching transistor during the peak current control mode of operation.

17 . A method, comprising:

monitoring an output voltage of a voltage regulator circuit to determine whether the output voltage falls below a predetermined voltage level due to a load current drawn by one or more electronic circuits coupled to the voltage regulator circuit;

in response to the output voltage falling below the predetermined voltage level, transitioning the voltage regulator circuit from a valley current control mode of operation to a peak current control mode of operation;

monitoring a transient current of the voltage regulator circuit during the peak current control mode of operation; and

in response to the transient current reaching an upper value of a limit current, transitioning the voltage regulator circuit from the peak current control mode of operation to the valley current control mode of operation.

18 . The method of claim 17 , further comprising:

operating the voltage regulator circuit in the valley current control mode of operation to provide a first steady state current, in response to the output voltage staying above the predetermined voltage level; and

operating the voltage regulator circuit in the valley current control mode of operation to provide a second steady state current, after the transient current reaches the upper value of the limit current.

19 . The method of claim 18 , wherein operating the voltage regulator circuit in the valley current control mode of operating to provide the first and second state currents comprises setting the limit current to a fixed current level.

20 . The method of claim 17 , wherein transitioning the voltage regulator circuit from the valley current control mode of operation to the peak current control mode of operation comprises increasing the limit current as the transient current increases until the upper value of the limit current is reached.