Qi Low Power Specifications
Free download of the specification
The Qi low power specification is available as free public download from this website. See http://www.wirelesspowerconsortium.com/downloads/wireless-power-specification-part-1.html
This document defines the interface for contactless power transfer between a power transmitter and a power receiver, based on near field magnetic induction between coils.
Test specification for members only
The Wireless Power Consortium created two additional documents
- Performance Requirements Specification. This document defines performance requirements for power transmitters and power receivers.
- Compliance Test Specification. This document defines the compliance test procedure for power transmitters and power receivers.
The Performance Requirements Specification and the Compliance Test Specification are available for members only. To join the WPC see: http://www.wirelesspowerconsortium.com/about/how-to-join.html
Numbering of Qi specifications
Qi specifications are numbered with three digits: X.Y.Z. For example 1.0.3
- X is called the major revision number. Specifications with the same major revision number are backward and forward compatible.
- Y is called the minor revision number. A change in minor revision number implies that new requirements are introduced while maintaining backward compatibility previously certified products
- Z is called the editorial revision number. Editorial revisions include clarifications, integrate new transmitter designs into one document, and may add new test to the test specifications.
Current version of the Qi specification
The current version of the Qi specification has version number 1.1.2
History of the Qi specification
- Qi transmitter delivers 5 Watt power into a Qi phone.
- Choice of transmitter designs include single coil transmitter, coil array transmitter, and moving coil transmitter.
- High flexibility in design of Qi receivers
- Limited flexibility in the design of Qi transmitters
- Increased design freedom for transmitters. You can now choose between 12 different transmitter specifications.
- Increased sensitivity of "Foreign Object Detection". This prevents heating of metal objects in the neighborhood of an active transmitter.
- The possibility to power a Qi transmitter with a USB charger.