Configurable charge controller

1. A power regulator comprising:

an adaptive low-dropout regulator configured to receive a variable output voltage, linearly regulate the variable output voltage to generate a first output voltage through a first output terminal in a first operating mode, and pass through the variable output voltage to the first output terminal in a second and a third operating mode;

a buck/boost converter configured to receive the first output voltage and generate a second output voltage through a second output terminal;

a controller configured to control the adaptive low-dropout regulator and the buck/boost converter based at least in part on the variable output voltage; and

a regulator output terminal coupled to the second output terminal and configured to provide an output voltage of the power regulator.

2. The power regulator of claim 1 , further comprising:

a controller configured to:

determine a target output voltage of the power regulator; and

control the adaptive low-dropout regulator and the buck/boost converter based at least in part on the variable output voltage and the target output voltage.

3. The power regulator of claim 2 , wherein the controller is further configured to determine the operating mode of the power regulator based at least in part on the variable output voltage, the target output voltage, and an input current.

4. The power regulator of claim 3 , wherein the buck/boost converter is configured to step-up the first output voltage in the second operating mode and step-down the first output voltage in the third operating mode.

5. The power regulator of claim 1 , wherein the controller is configured to control a power supply configured to provide the variable output voltage.

6. An adaptive low-dropout regulator comprising:

a field effect transistor (FET) configured to receive an output voltage from a variable output power supply;

a headroom detection circuit coupled to the FET and configured to measure a voltage difference between source and drain terminals of the FET; and

a power supply controller coupled to the headroom detection circuit and configured to adjust the variable output power supply based at least in part on the measured voltage difference, comprising:

a first output configured to provide a first signal to increase the output voltage of the variable output power supply, and

a second output configured to provide a second signal to decrease the output voltage of the variable output power supply, wherein the first output is separate from the second output.

7. The adaptive low-dropout regulator of claim 6 , wherein the power supply controller is further configured to maintain a first voltage difference between the source and drain terminals of the FET by controlling the output voltage of the variable output power supply.

8. The adaptive low-dropout regulator of claim 6 , wherein the FET is configured to operate in a linear mode based at least in part on the output voltage from the variable output power supply.

9. The adaptive low-dropout regulator of claim 6 , wherein the FET is configured to provide a system voltage for a system load.

10. The adaptive low-dropout regulator of claim 9 , wherein the power supply controller is configured to adjust the variable output power supply to maintain the measured voltage difference between the output voltage of the variable output power supply and the system voltage.

11. The adaptive low-dropout regulator of claim 6 further comprising a FET controller coupled to the FET and configured to control a gate voltage based at least in part on a detected current or detected voltage.

12. A power regulator comprising:

an adaptive low-dropout regulator configured to receive a first intermediate voltage and generate a first output voltage through a first output terminal;

a buck/boost converter configured to receive the first intermediate voltage and generate a second output voltage through a second output terminal coupled to the first output terminal;

a power regulator output terminal configured to receive the first output voltage from the first output terminal and the second output voltage from the second output terminal;

a controller configured to control the adaptive low-dropout regulator and the buck/boost converter based at least in part on a variable input voltage of the power regulator; and

a first field effect transistor (FET) configured to receive the variable input voltage and generate the first intermediate voltage for the adaptive low-dropout regulator and the buck/boost converter.

13. The power regulator of claim 12 , further comprising:

a FET controller configured to operate the first FET as a linear regulator.

14. The power regulator of claim 12 , wherein the controller is configured to:

determine a target output voltage of the power regulator;

determine an operating mode of the power regulator based at least in part on the variable input voltage and the target output voltage of the power regulator; and

control the adaptive low-dropout regulator and the buck/boost converter based at least in part on the operating mode of the power regulator.

15. The power regulator of claim 14 , wherein the controller is configured to:

enable the adaptive low-dropout regulator and disable the buck/boost converter if the operating mode of the power regulator is a first operating mode; and

disable the adaptive low-dropout regulator and enable the buck/boost converter if the operating mode of the power regulator is a second operating mode.

16. The power regulator of claim 12 , wherein the adaptive low-dropout regulator comprises:

a second FET configured to receive the first intermediate voltage, and generate the first output voltage.

17. The power regulator or claim 16 , wherein the second FET is configured to operate in a linear mode.