P9242-R3/RB Datasheet

© 2019 Integrated Device Technology, Inc.

20

May 17, 2019

7.12 LC Resonant Circuit

The LC resonant circuit comprises the series primary resonant coil (LP) and series capacitance (CP) in the typical application circuit as shown

in Figure 18. The transmitter coil assembly is vendor specific, and it must comply with the WPC recommendation. The WPC recommendations

include the self-inductance value, DC resistance (DCR), Q-factor, size, and number of turns.

The P9242-R3 is designed to support various Extended Power Profile (EPP) coil configurations (see section 12.2) using half-bridge and full-

bridge inverter topologies to drive the primary coil (LP) and a series capacitance (CP). Depending on the WPC coil configuration selection, the

coil inductance and series capacitance will change. Near resonance, the voltage developed across the CP series capacitance could reach 70V

peak (voltage may change depending on the coil configuration). High-voltage (100V) COG-type ceramic capacitors are highly recommended

for their AC and DC characteristics and temperature stability. The recommended parts are listed on the bill of materials (BOM) in Table 27.

Figure 18. Typical Application Diagram with Resonant Circuit

Peak

Detector

P9242-R3

SW_S

LDO33

LDO18

PREG

VIN_LDO

RSNS

Programming

Resistors

GH_BRG1

SW_BRG1

GL_BRG1

GH_BRG2

SW_BRG2

GL_BRG2

ILIM/FOD

LED/Q-fact

LP

CP

L

7.13 External Memory

The P9242-R3 has the bootloader and application firmware pre-programmed into the internal one-time programmable (OTP) memory and does

not allow users to customize the firmware. The P9242-RB, which is pin-to-pin compatible with the P9242-R3, has only a bootloader pre-

programmed into the internal OTP memory. Therefore, the P9242-RB must be used in conjunction with an external flash memory. Application

firmware is loaded into the external flash for specific system requirements.

The P9242-RB fetches the application firmware from the external flash memory using an SPI interface and executes the code. Users can

customize the firmware in external flash and load the new firmware in the flash via the P9242-RB I2C port. There is no functionality difference

between the P9242-R3 IC and the P9242-RB with an external flash. The Winbond W25X20CLUXIG or any other Winbond W25X series flash

device is the recommended external flash memory to be used with the P9242-RB.