Demonstration circuit 2181A-A features the LTC4120-4.2 wireless power receiver with 400mA synchronous step-down CC/CV (4.2V charge voltage) battery charger. The DC2181 is used with the DC1968A wireless power transmitter or the PowerByProxi ProxiPoint transmitter. Either can deliver 2W to the DC2181, with up to 10mm spacing between the transmitter and the receive coil. The basic transmitter doesn’t support foreign metal object detection.