Date Posted: September 12, 2011 10:34 AM
Author: Tony Antonacci, Steve Terry
Standardization among different transmitters and receivers receives high priority within the emerging wireless-power market. Previously, any company that sold a wireless-power receiver also had to sell a corresponding transmitter. This hinders the market adoption of wireless power, and eventually leads to a proliferation of different, incompatible wireless power technologies. To address the problem, the Wireless Power Consortium (WPC) came up with Qi (pronounced “chee”)—the first global standard that enables interoperability between compliant transmitters and receivers at power levels up to 5 W.1 The Qi standard, introduced in July 2010, defines the operating frequency, operating voltages, and basic coil configurations for a wireless-power system. In addition, a communication protocol is defined whereby a receiver can communicate information to a transmitter, such as when the transmitter should terminate power (i.e., enter a power-saving mode when the phone is no longer charging), how much power the receiver requires, and whether output power should be increased or decreased. The end result is that accessory products now can offer wireless power for a mobile device without the need for a basestation (wireless power transmitter). A common approach is to offer a sleeve, back door, battery pack, or holster that contains the receiver coil and electronics in the accessory product. Continue Reading Here