Battery charging systems and methods with adjustable current limit

A circuit comprising:

• a regulator, the regulator having in input to receive voltage and current from an external power source and an output to provide power to an electronic device, wherein the external power source has a maximum current and the voltage from the external power source collapses when the current from the external power source is above the maximum current;
• an input voltage detection circuit having an input to receive the voltage from the external power source and detect when the voltage from the external power source collapses below a threshold voltage;
• and
• a current limit circuit to limit current in the regulator;
• wherein the current limit circuit is reconfigured to a plurality of current limit values and the input voltage detection circuit detects if the voltage from the external power source collapses below the threshold voltage at the plurality of current limit values to find a maximum current limit value below the maximum current of the external power source.

A circuit comprising:

• a regulator, the regulator having in input to receive voltage and current from an external power source and an output to provide power to an electronic device, wherein the external power source has a maximum current and the voltage from the external power source collapses when the current from the external power source is above the maximum current;
• a current limit circuit for limiting current in the regulator;
• means for configuring the current limit circuit to a plurality of current limit values;
• and
• means for detecting, at the plurality of current limit values, if the voltage from the external power source collapses below a threshold voltage to find a maximum current limit value below the maximum current of the external power source.