In-band communication during wireless battery charging

A method of charging a battery using wirelessly received power, the method comprising:

• using a receiver coil to receive power wirelessly at a wireless power receiver (RX);
• outputting power from an output of the wireless power RX to a bus based on the wirelessly received power;
• using the receiver coil to wirelessly communicate from the wireless power RX to a transmitter of the wireless power;
• enabling an open-loop DC-DC converter having an input coupled to the bus and an output coupled to a terminal configured to be coupled to a battery to use the power output to the bus by the wireless power RX to charge the battery;
• and
• controlling a linear regulator that is connected in an electrical power pathway from the output of the wireless power RX to the terminal to stabilize a current in the bus at the output of the wireless power RX to reduce interference to the wireless communication when using the receiver coil to wirelessly communicate from the wireless power RX to the transmitter while the open-loop DC-DC converter is being used to charge the battery, the electrical power pathway has a portion that passes from the input of the open-loop DC-DC converter to the output of the open-loop DC-DC converter.

An apparatus for charging a battery using wirelessly received power, the apparatus comprising:

• a power bus;
• a wireless power receiver (RX) comprising a receiver coil, the wireless power RX configured to use the receiver coil to receive power wirelessly and to communicate wirelessly to a transmitter of the power, the wireless power receiver configured to output direct current (DC) power to the power bus based on the wirelessly received power;
• a closed-loop DC-DC converter having an input coupled to the power bus and an output configured to be coupled to the battery;
• an open-loop DC-DC converter having an input coupled to the power bus and an output configured to be coupled to the battery;
• a linear regulator coupled serially with the open-loop DC-DC converter;
• and
• a controller configured to selectively enable one of the closed-loop DC-DC converter or the open-loop DC-DC converter at a time to use the DC power output to the bus by the wireless power RX to charge the battery;
• the controller further configured to control the linear regulator to stabilize a current on the bus at the output of the wireless power RX to reduce interference to the wireless communication caused by transient load current when using the receiver coil to wirelessly communicate from the wireless power RX to the transmitter of the power while the open-loop DC-DC converter is being used to charge the battery.