At present, the mainstream flagship mobile phones on the market are equipped with wireless charging function, the universal protocol wireless charger power has also developed from 5W to 15W, and the fast charger power has also moved from QC 18W to PD 20W. However, there is a problem here, the power supply input power of 15W wireless charger needs to reach 20W, most of the 20W chargers on the market are a new generation of PD chargers, and the use of ordinary 18W QC chargers cannot make 15W wireless charger reach full load, if the PD chip is added to the 15W wireless charger, it will increase the cost. Therefore, the 15W wireless charging market has a great demand for 20W USB-A chargers.