The present invention relates to wireless power feeding technology for wirelessly supplying power from the transmission side to the receiving side, and is particularly and preferably applicable to a wireless charging circuit and a wireless charging system, used for charging a battery by wireless power feeding, and a semiconductor device used therefor.
Patent document 1 (Japanese Patent Laid-Open No. 2003-141484) describes a non-contact/contact IC card which can transmit and receive signals via a non-contact interface even if sufficient power supply is not obtained in a non-contact manner. Particularly, paragraph 0016 of the Patent Document 1 describes a configuration for performing power feeding and communication in a non-contact manner.
In addition, NFC (Near Field Communication) can be exemplified as non-contact communication technology. NFC, an international standard of low power wireless communication technology for a distance of about ten centimeters, is being incorporated in small mobile terminals such as smart phones. In contrast, a technique referred to as wireless charging capable of non-contact (also referred to as “wireless”) power supply is being on the rise, and a group named WPC (Wireless Power Consortium) has entered the market with expectation of promoting the contactless charging standard (Qi).
Patent Document 2 (Japanese Patent Laid-Open No. 2009-253649) describes, a technique of controlling the operation of an information transmission means of performing wireless information transmission and a power transmission means of performing non-contact power transmission, between communication devices having the information transmission means and the power transmission means.