The A4WP power receiving unit, PRU is the element of the A4WP charging system that is fitted into the item that required power to be transferred into it for charging.
The A4WP power receiving unit accepts power from a charger / transmitter and links with it during the charging process to enable control messages to be exchanged between the two for efficient charging to be effected.
A4WP PRU basics
The A4WP power receiving unit is very much the inverse of the transmitter.
It contains a similar number of blocks, although performing different functions, so that the power received via the receiver resonator can be converted into power at the required voltage level.
Power enters the receiver via the resonator. It is rectified to provide a DC voltage. The rectifier needs to be able to provide efficient rectification at the 6MHz frequencies used.
Once rectified, the power is converted to the required voltage using an efficient DC-DC switch mode converter.
Both the rectifier and the DC-DC converter can be controlled over the 2.4GHz link to the charger to enable both charger and A4WP receiving unit to communicate and provide the most efficient power transfer.