Dual-mode high-efficiency voltage regulator for wireless charging modules

A method, comprising:

• receiving power wirelessly;
• rectifying the received power to produce a rectified voltage;
• in a startup condition:
• enabling a low dropout regulator circuit, the low dropout regulator circuit generating an output voltage from the rectified voltage;
• and
• powering internal analog and digital circuitry using the output voltage by coupling the output voltage to the internal analog and digital circuitry;
• and
• when startup is complete:
• reducing the output voltage generated by the low dropout regulator circuit;
• enabling a switching regulator;
• coupling an output voltage of the enabled the switching regulator to the internal analog and digital circuitry;
• and
• then disabling the low dropout regulator circuit.

An electronic device, comprising:

• internal analog and digital circuitry;
• a battery;
• a battery charging circuit;
• a receiver coil receiving wirelessly transmitted power and generating an AC input voltage therefrom;
• a rectifier rectifying the AC input voltage to produce a rectified voltage;
• a low dropout regulator that, during a first phase, generates a first regulated output voltage from the rectified voltage;
• a first switch that couples the first regulated output voltage to a voltage output node during the first phase to power the internal analog and digital circuitry;
• wherein the low dropout regulator, during a second phase, generates a second regulated output voltage from the rectified voltage, the second regulated output voltage being lesser in magnitude than the first regulated output voltage;
• wherein the first switch couples the second regulated output voltage to the voltage output node during the second phase;
• a switching regulator that generates a third regulated output voltage during the second phase, the third regulated output voltage being greater than the second regulated output voltage;
• and
• a second switch that couples the third regulated output voltage to the voltage output node during the second phase;
• wherein the low dropout regulator, during a third phase, is disabled, while the switching regulator continues to generate the third regulated output voltage during the third phase;
• wherein the first switch opens during the third phase while the second switch remains closed during the third phase;
• and
• a power supply circuit receiving the rectified voltage and generating therefrom a power supply signal for powering the battery charging circuit, during the first, second, and third phases.

A wireless charging module, comprising:

• a wireless power receiver configured to wirelessly receive power and generate therefrom a rectified voltage;
• a low dropout regulator that, in response to lack of assertion of a low dropout amplifier disable signal, generates a first regulated output voltage from the rectified voltage;
• and
• a first switch that couples the first regulated output voltage to a voltage output node to thereby power at least one internal circuit, in response to lack of assertion of the low dropout amplifier disable signal;
• wherein the voltage output node, in response to an external voltage enable signal being asserted, receives an external voltage, and the low dropout regulator generates a second regulated output voltage from the rectified voltage so as to transition the at least one internal circuit to being powered by the external voltage, the second regulated output voltage being lesser in magnitude than the first regulated output voltage;
• wherein the low dropout amplifier, in response to assertion of the low dropout amplifier disable signal, is disabled;
• and
• wherein the first switch opens in response to assertion of the low dropout amplifier disable signal.