Datasheet

Tx Powered

without Rx

Active

Identification and

Configuration and SS,

Received by Tx?

Yes

Tx Extended Digital Ping

Power Contract

Established. All

proceeding control is

dictated by the Rx.

VRECT < 7V?

Send control error packet

to increase VRECT

Yes

Startup operating point

established. Enable the

Rx output.

EN1/EN2/AD/TS-CTRL

EPT Condition?

Send EPT packet with

reason value

Yes

Rx Active

Power Transfer

Stage

bq51013B

SLUSB62A –MARCH 2013–REVISED OCTOBER 2013

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Figure 27. Wireless Power Startup Flow Diagram

Once the startup procedure has been established, the Rx will enter the active power transfer stage. This is

considered the “main loop” of operation. The Dynamic Rectifier Control algorithm will determine the rectifier

voltage target based on a percentage of the maximum output current level setting (set by K

IMAX

and the ILIM

resistance to GND). The Rx will send control error packets in order to converge on these targets. As the output

current changes, the rectifier voltage target will dynamically change. As a note, the feedback loop of the WPC

system is relatively slow where it can take up to 90 ms to converge on a new rectifier voltage target. It should be

understood that the instantaneous transient response of the system is open loop and dependent on the Rx coil

output impedance at that operating point. More details on this will be covered in the section Receiver Coil Load-

Line Analysis. The “main loop” will also determine if any conditions in Table 4 are true in order to discontinue

power transfer. See Figure 28 which illustrates the active power transfer loop.

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