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BQ500212A FOD Fail

Bill Johns
Guru* 75656 points

Original Post by Avraka

Dear BIll

Regarding to the changes between 1.1.1 and 1.1.2, TPR #6 Coil test is added.

In 1.1.1, there are no issues. But 1.1.2 induce FOD and Temperature fails with the same TX board which is adopting BQ500212A.

In the beginning I used 3 COG + 1 X7R as a resonance cap. In this case, FOD is OK, but temperature is increasing.

If I use 4 COG, Temperature is OK. But It make a failure of FOD and TPR#6 Coil Test.

Making me know how to fix this issues would be appreciated.

Thanks

  • 0
    TI__Guru* 75656 points

    FOD calibration must be run on all new designs to set FOD Threshold resistor and FOD Cal resistor before WPC certification.

    Resistor values from EVM can be used as a starting point only. 

    FOD Threshold resistor – Pin 17 to Pin 43

    FOD Cal resistor – Pin 15 to Pin 43

    Changes in the power section will change FOD performance and require recalibration.

    “In the beginning I used 3 COG + 1 X7R as a resonance cap. In this case, FOD is OK, but temperature is increasing.”

    “If I use 4 COG, Temperature is OK. But It make a failure of FOD and TPR#6 Coil Test.”

    The type of change described above will change loss in the power section and FOD performance, FOD recalibration will be required. 

    FOD Cal acts as compensation for change in the power section and will flatten out the loss profile over load.   FOD Threshold sets the trip point where a fault will be set.