Qi (standard)
The Qi logo, consisting of a lowercase "q" with a semicircle-esque "i" with a circle on top
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| Status | Active |
|---|---|
| Year started | 2008 |
| First published | 2008 |
| Latest version | 1.2.2 |
| Organization | Wireless Power Consortium |
| Committee | Wireless Power Consortium |
| Domain | Inductive charging |
| License | Open standard |
| Copyright | Logo and trademark |
Qi (pronounced CHEE;IPA: /tʃiː/, meaning "natural energy") is an open interface standard developed by the Wireless Power Consortium for inductive charging over distances of up to 4 cm (1.6 inches). The system uses a charging pad and a compatible device, which is placed on top of the pad, charging via resonant inductive coupling.
Mobile device manufacturers that are working with the standard include Apple inc., Asus, HTC, Huawei, LG Electronics, Motorola Mobility, Nokia, Samsung, BlackBerry, and Sony. According to a list of Qi devices by Qi Wireless Charging, July 14, 2016 there were over 140 smartphones, tablets and other devices which can be charged wirelessly with Qi.
Under the Qi specification, "low power" for inductive transfers denotes power deliveries below 5 W. Systems that fall within the scope of this standard are those that use inductive coupling between two planar coils to transfer power from the power transmitter to the power receiver. The distance between the two coils is typically 5 mm. It is possible to extend that range to at least 40 mm. Regulation of the output voltage is provided by a digital control loop where the power receiver communicates with the power transmitter and requests more or less power. Communication is unidirectional from the power receiver to the power transmitter via backscatter modulation. In backscatter modulation, the power-receiver coil is loaded, changing the current draw at the power transmitter. These current changes are monitored and demodulated into the information required for the two devices to work together.
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