P9415-R-EVK Evaluation Kit
R16UH0015EU0100 Rev.1.0
May 27, 2021
Page 18
11.7 GP2/ External Thermistor Pin
The GP2 pin is connected to the internal ADC and can measure the voltage of the thermistor connected to
measure the external temperature on either the receiver coil or the PCB. The P9415-R sends interrupts to the
AP if the voltage reaches below the threshold level (0.6V default, configurable) to allow the AP an opportunity to
reduce the temperature and prevent power transfer interruptions. The AP must convert the ADC value into a pin
voltage using the below equation. Voltage can be converted into temperature information based on the
thermistor manufacturer datasheet information.
Equation:
Voltage on GP2 Pin in mV = (Register 0x42 [11: 0] Data / 4095)
∗
10
∗
2.1
Figure 18. GP2 Pin External Connection to Thermistor Configuration
11.8 GP4/I2C Address Select Pin
The pin is used to select the P9415-R device I2C slave address. When this pin is pulled high to LDO1P8, I2C
Address is 0x3F and when this pin pulled low to GND, I2C Address is 0x3B (default). The slave address is a 7-
bit I2C address.
11.9 GP5/INHIBIT Pin
The GP5 / INHIBIT pin is a digital input referenced to LDO1P8 and gets polled during the startup. When the
INHIBIT pin is low, the Rx mode is enabled. Pulling the INHIBIT pin high will prevent the P9415-R from
connecting to the transmitter. The AP can use this pin to safely enable and disable wireless power transfer
function with proper VRECT node protections. If this pin is driven high in the power transfer phase, the P9415 R
will send an End Power Transfer packet to the transmitter and wireless power transfer will be disabled while
VRECT protection is alive.
11.10 GP6/EPP_DISABLE Pin
The GP6 is assigned as a digital input referenced to LDO1P8. When the EPP_DISABLE pin is high, the Rx EPP
mode is disabled and the P9415-R operates in BPP mode. When it is low, the Rx mode is determined by the
internal mode configuration setting value in the firmware. If not used, connect this pin to ground.
12. Foreign Object Detection
When metallic objects are exposed to an alternating magnetic field, eddy currents cause such objects to heat up.
Examples of such parasitic metal objects are coins, keys, paper clips, etc. The amount of heating depends on
the strength of the coupled magnetic field, as well as the characteristics of the object, such as its resistivity, size,
and shape. In a wireless power transfer system, the heating manifests itself as a power loss, and therefore a
reduction in power-transfer efficiency. Moreover, if no appropriate measures are taken, the heating could be
sufficient that the foreign object could become heated to an unsafe temperature.
