P9221-R Datasheet

© 2017 Integrated Device Technology, Inc.

18

October 10, 2017

8.6

Interrupt Function – INT

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The P9221-R provides an open-drain, active-LOW interrupt output pin. It is asserted LOW when EN is HIGH or any of the following fault

conditions have been triggered: the die temperature exceeds 140°C, the external thermistor measurement exceeds the threshold (see section

8.9), or an over-current (OC) or over-voltage (OV) condition is detected.

During normal operation, the INT pin is pulled HIGH. This pin can be connected to the interrupt pin of a microcontroller. The source of the trigger

for the interrupt is available in the I2C Interrupt Status register (see Table 13).

8.7

Enable Pin – EN

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The P9221-R can be disabled by applying a logic HIGH to the EN pin. When the EN pin is pulled HIGH, the device is in Shut-Down Mode.

Connecting the EN pin to logic LOW activates the device.

8.8

Thermal Protection

The P9221-R integrates thermal shutdown circuitry to prevent damage resulting from excessive thermal stress that may be encountered under

fault conditions. This circuitry will shut down or reset the P9221-R if the die temperature exceeds 140°C.

8.9

External Temperature Sensing and End of Charge – TS/EOC

The P9221-R has a temperature sensor input which can be used to monitor an external temperature by using a thermistor. The built-in

comparator’s reference voltage is 0.6V and 0.1V in the P9221-R, and it is used for monitoring the voltage level on the TS/EOC pin as described

by Equation 1.

VTS=VVDD18×

NTC

R+NTC

Equation 1

Where NTC is the thermistor’s resistance and R is the pull-up resistor connected to VDD18 pin. The over–temperature shutdown is trigged

when the TS pin voltage is between 0.6V and 0.1V; for more information, see Figure 24.

When the TS/EOC pin is less than 0.1V, the End of Charge (EOC) function is activated, and the P9221-R will send the End Power Transfer

(EPT) packet to the transmitter terminating the power delivery.

8.10 Alignment Guide – ALIGNX and ALIGNY

This feature is used to provide directional information regarding the transmit coil and receive coil alignment while the wireless charger is in

normal operation mode. Sensing coils (see the basic application circuit on the first page) are placed on the wireless power receiver side between

the power Rx coil and power Tx coil. Special design enables the sensing coils to output zero voltage when the alignment is optimum while

misalignment between the transmitter and receiver coils will result in a voltage on the sensing coils. These signals are internally rectified, filtered,

and passed through the ADC providing quantitative information on the amount of misalignment. The higher the signal is, the more the coils are

misaligned.

Furthermore, the signal magnitude on ALIGNX and ALIGNY provides directional information by measuring the phase between the input power

AC signal and horizontal and vertical alignment signals. Once the signal passes through the ADC, the alignment information is represented by

two 8-bit signed numbers, which can be read from the Alignment X Value and Alignment Y Value I2C registers defined in Table 22 and Table

23 respectively, which indicate the misalignment direction and magnitude.

The application processor can provide 2D visual graphics that suggest how much the power coils are misaligned in each direction and can

suggest that the user move the device on the Tx pad for the best alignment to improve the power transferred and reduce the charging time.