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BQ51050B cross talk

Other Parts Discussed in Thread: BQ51050B

Hello, 

I designed a Wireless Charging Board using BQ51050B and Linear Technology Fuel Gauge IC LTC2942. The problem is when wireless charging is active I receive 10% wrong values from LTC2942 I2C interface. 
I decoupled the Transmitter/Receiver Coils from the board so that direct AC magnetic field don't introduce any interference but the problem persists.
Image of Layout is attached. Kindly help me in diagnosis that IS it a cross talk issue between BQ51050B and LTC2942 or there may be some other issue as well.

  • Ahmad,

    Have you probed the I2C lines to see the interference?  

    Does the interference occur during all wireless charging stages or only certain current levels (precharge / constant current / taper)?

    What capacitor values are you using on the COMM1 and COMM2 pins?

    In general, it is a good idea to keep the COMMx and AC1/AC2 lines away from signal lines.

    Regards,

    Dick

  • Hello Dick Stacey,

    Thank you for your answer.

    1)  I used NI data acquisition hardware NI-6001 to observe interference and Yes it seems to be crosstalk issue between  I2C lines and  BQ COMM line.

    2) I am using 22nF capacitors on COMM1 and COMM2 pins.

    Regards,

    Ahmad