Wireless charging for an input device

A method of operating a computer mouse comprising:

• determining whether an external wireless power source is coupled to an interface configured to transfer power from the external wireless power source to a power management system;
• selecting the external wireless power source to power the computer mouse based on a determination that the external wireless power source is electrically coupled to and providing power to the interface;
• determining whether a fixed internal power source is coupled to a power management system;
• selecting a fixed internal power source to power the computer mouse based on a determination that the fixed internal power source is coupled to the power management system and the external wireless power source is coupled to but not providing enough power to the interface,
• determining whether a removeable internal power source is electrically coupled to the power management system in the computer mouse;
• and
• selecting the removeable internal power source to power the computer mouse based on a determination that the removeable internal power source is electrically coupled to the power management system and the external power source is not coupled to the interface,
• wherein the fixed internal power source is a charge storage device configured to be charged by the external power source via a charging circuit, the charging circuit including a current limiter comprising:
• a first low-dropout voltage (LDO) regulator circuit that is biased in a floating output configuration;
• and
• a second LDO regulator circuit configured to regulate its output voltage to a level that is within a normal operational range of the fixed internal power source,
• wherein the first LDO regulates its output voltage across an output resistor thereby generating a constant current that passes through the second LDO and charges the fixed internal power source until the second LDO reaches and regulates at a predetermined voltage, thereby causing the first LDO to stop regulating until the output of the second LDO drops below the predetermined voltage.

A system comprising:

• one or more processors;
• one or more machine-readable, non-transitory storage mediums that include instructions configured to cause the one or more processors to perform operations including:
• determining whether an external wireless power source is coupled to an interface configured to transfer power from the external wireless power source to a power management system of a computer mouse;
• selecting the external wireless power source to power the computer mouse based on a determination that the external wireless power source is electrically coupled to and providing power to the interface;
• determining whether a fixed internal power source is coupled to the power management system;
• selecting a fixed internal power source to power the computer mouse based on a determination that the fixed internal power source is coupled to the power management system and the external wireless power source is coupled to but not providing enough power to the interface;
• determining whether a removeable internal power source is electrically coupled to a power management system in the computer mouse;
• and
• selecting the removeable internal power source to power the computer mouse based on a determination that the removeable internal power source is electrically coupled to the power management system and the external power source is not coupled to the interface,
• wherein a charging circuit operable to charge the fixed internal source includes a current limiter comprising:
• a first low-dropout voltage (LDO) regulator circuit that is biased in a floating output configuration;
• a second LDO regulator circuit configured to regulate its output voltage to a level that is within a normal operational range of the fixed internal power source,
• wherein the first LDO regulates its output voltage across an output resistor thereby generating a constant current that passes through the second LDO and charges the fixed internal power source until the second LDO reaches and regulates at a predetermined voltage, thereby causing the first LDO to stop regulating until the output of the second LDO drops below the predetermined voltage.