P9412 Datasheet

R35DS0011EU0120 Rev.1.2

Jul.6.21

Page 20

3.13.11. Negotiation

The Power Receiver negotiates with the Power Transmitter to fine-tune the Power Transfer Contract. For this

purpose, the Power Receiver sends negotiation requests to the Power Transmitter, where the Power Transmitter

can grant or deny.

3.13.12. Calibration

The Power Receiver provides its Received Power back to the Power Transmitter.

3.13.13. Power Transfer

In this phase, the P9412 controls the power transfer by means of the following Control Data Packets:

•

Control Error Packets

•

Recieved Power Packets

•

End Power Transfer Packet

3.13.14. Renegotiation

In this phase, the Power Receiver can make adjustments to the Power Transfer Contract, if so desired. If

necessary, this phase can be aborted prematurely without changing the Power Transfer Contract.

3.13.15. End of Power Transfer (EPT)

In the event of EPT, the P9412 will continuously send End of Power (EPT) packets until the transmitter removes

the power and the rectifier voltage on the receiver side drops below the UVLO threshold.

3.14

External Components

The P9412 requires a minimum number of external components for proper operation. For required external

components and values and the wiring diagram, see the reference schematic in Figure 16.

3.15

Rx Wireless Power Coil

The Rx coil is dependent on customer requirements since most are custom designs. Renesas recommends the

following typical values for Rx-only coils:

Ls = 8 to 10

µH

DCR = < 0.3

Ω

ACR = < 0.4

Ω

For TRx coil design guidance, see Application Note AN-1039 TRx Coil Guide v17. It is recommended to closely

follow these coil design guidelines to avoid WPC certification issue’s or other power transfer relates obstacles

that may lead to delays in production launches caused by improper coupling or unexpected operating conditions.

3.16

Resonance Capacitors

The series resonance capacitors are critical components and must be chosen carefully. All current that flows to

the load flows through these components, plus any current lost in the rectifier AC to DC conversion and

Capacitive Divider conversion. The recommended capacitor is the 100nF Murata (GRM155R61H104KE19D,

0402, X7R, 50V), which have an ESR ~ 0.1ohms at 100kHz. This capacitor should be selected based on ESR

value and DC bias effects. If another capacitor is chosen, inspecting the ESR versus Frequency curve of the

manufacturer’s capacitor datasheet is necessary to compare ESR characteristics, as well as the DC bias effects

on the capacitor value (equivalent or lower ESR and equivalent or higher DC bias at 15V DC applied should be

used to select substitutions). Adding an additional non-populated (NP) component placement (C6) is advised if

additional capacitance is needed for a particular Rx or TRx coil.

3.17

Input Capacitor (VRECT Capacitors)

The LDO input capacitors (VRECT capacitors) should be located as close as possible to the VRECT pins and

ground (PGND). Ceramic capacitors are recommended for their low ESR and small profile. The DC bias effects