Qi wireless power transmitter circuit with foreign object detection

January 28, 2014 // By Graham Prophet
For Qi wireless charging stations, Texas Instruments has added an integrated WPC 1.1-compliant controller that reduces component count, and that gives smartphone users greater flexibility to charge from 5-V or 12-V charging stations

The next-generation wireless power transfer circuit with foreign object detection will be the basis of 3-coil, 5-V and 12-V A6 charging stations compliant with the Wireless Power Consortium (WPC) 1.1 specification. The bq500412 controller requires half the components compared to other solutions.

Giving users improved charging, the bq500412 integrates all functions required to control wireless power delivery from the charging station to a receiver circuit used in a Qi-enabled smartphone or other device. In addition to 12-V charging pads, the circuit can be combined with a boost converter to create a 3-coil, 5-V USB charging pad, while taking advantage of a Dynamic Power Limit feature to ensure quality operation independent of the power capability of the port.

The bq500412 also supports an enhanced foreign object detection scheme, which makes it easier for designers to implement the requirements of the WPC 1.1 specification.