P9242-R Datasheet

© 2018 Integrated Device Technology, Inc

23

January 16, 2018

9. WPC Mode Characteristics

The WPC-1.2 extended power profile wireless power specification has a negotiation phase, calibration phase, and renegotiation phase, as

shown in Figure 23.

Figure 23. WPC Power Transfer Phases Flow Chart

START

Object

detected

Error condition

Negotiation failure or

error condition or FOD

Calibration

successful

Negotiation

successful

Negotiation requested

No negotiation requested

(<= 5W power received only)

Renegotiation

completed

Calibration failure or

error condition

No response or

no power needed

Selection

Ping

Identification and

Configuration

Negotiation

Renegotiation

Calibration

Power Transfer

Power receiver

present

Power transfer complete

or error condition

Renegotiation

requested

Error

condition

9.1 Selection Phase

In the selection phase, the power transmitter determines if it will proceed to the ping phase after detecting the placement of an object. In this

phase, the power transmitter typically monitors the interface surface for the placement and removal of objects using a small measurement

signal. This measurement signal should not wake up a power receiver that is positioned on the interface surface.

9.2 Ping Phase (Digital Ping)

In the ping phase, the power transmitter will transmit power and will detect the response from a possible power receiver. This response ensures

the power transmitter that it is dealing with a power receiver rather than some unknown object. When a power receiver is placed on a WPC “Qi”

charging pad, it responds to the application of a power signal by rectifying this power signal. When the internal bias voltage is greater than a

specific threshold level, then receiver is initiated enabling the WPC communication protocol.

If the power transmitter correctly receives a signal strength packet, the power transmitter proceeds to the identification and configuration phase

of the power transfer, maintaining the power signal output.