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BQ500212A: BQ500212A

Part Number: BQ500212A

Hi,

we have designed a wireless charging station using the BQ500212A.
The PCB is up and running but we face some problems in configuring the Foreign object detection, understanding the calculations and the LED bits.
We use an I2C adaptor to read the status of thip, here are our qestions:

1) How to interpret the led out value (8 Bits to corresponding 2 LED's)
    We don't unterstand the coding.

2) Parasitic loss without a foreign object is shown as negative value?

3) Resistors in our design:
FOD_CAL = 86,6K
PMOD = none (left open)
FOD = 68K

4) How to define the 3 resistors for FOD_CAL, FOD and PMOD

Is there any instruction available how to derive these values for our design?

Here are the logs of the data we read from the BQ500212A.

********************** Charging without Foreign object ***************************

Readout every ~100ms
Led Mode = 2
Led_out before charging = 20
Led_out during charging = 5

Example of readout
037 Input power = 1891,58mW
DC = 5,0225 DC (mA) = 376,625 = 1891,59mW
Max. power = 10 -> 10 * 500mW -> 5W
Received power = 44 -> 5W / 128 * 44 -> 1,718W
Temperature = 25,77
Frequency = 126,28kHz
Threshold = 450mW
Parasitic loos = -215,29mW
Led out = 5

049 Input power = 1912,3mW
DC = 5,0225 DC (mA) = 380,75 = 1912,31mW
Max. power = 10 -> 10 * 500mW -> 5W
Received power = 43 -> 5W / 128 * 43 -> 1,679W
Temperature = 25,58
Frequency = 126,89kHz
Threshold = 450mW
Parasitic loos = -281,96mW
Led out = 5


**************** Charging with Foreign object *****************************

Readout every ~100ms
Led Mode = 2
Led_out before charging = 20
Led_out start charging = 5
Led_out FOD warning = 18
Led_out detect FOD = 16
Led_out remove receiver = 20


Example of readout:
034 Input power = 5667,93mW
DC = 4,8584 DC (mA) = 1166,625 = 5667,93mW
Max. power = 10 -> 10 * 500mW -> 5W
Received power = 53 -> 5W / 128 * 53 -> 2,070W
Temperature = 24,72
Frequency = 127,34kHz
Threshold = 400mW
Parasitic loos = 1106,91mW
Led out = 5

First change to led_out = 18
046 Input power = 1395,82mW
DC = 5,0391 DC (mA) = 277 = 1395,83mW
Max. power = 10 -> 10 * 500mW -> 5W
Received power = 5 -> 5W / 128 * 5 -> 0,195W
Temperature = 24,33
Frequency = 160,2kHz
Threshold = 400mW
Parasitic loos = 966,24mW
Led out = 18

Last led_out = 18
128 Input power = 3522,53mW
DC = 4,9482 DC (mA) = 711,875 = 3522,50mW
Max. power = 10 -> 10 * 500mW -> 5W
Received power = 5 -> 5W / 128 * 21 -> 0,820W
Temperature = 24,72
Frequency = 134,13kHz
Threshold = 400mW
Parasitic loos = 1616,85mW
Led out = 18

Led out changed to 16!