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BQ51221 Problems/Troubleshooting

Jason Luzinski
Prodigy 100 points
Other Parts Discussed in Thread: BQ51221

Hello,

I have a TI BQ51221EVM-520 that is experiencing problems.  My current test setup consists of a coil that is double the inductance of coil provided with the original EVM with tuning (C1,C2,C3) and com(C4,C5) caps set  as per Qi spec.  The transmitter I have been using is a TI BQ500410AEVM with and A6 coil.  Upon placing the evm with modified coil on the center A6 coil, the transmitter board beeps and the light begins to flash, which is normal operation if communication has been established and power transfer has begun.  The problem is on the receiver side.  The green LED flashes on every 3-4 seconds and there is an audible noise that comes from the EVM.  With and E-Load attached to the output of the evm, I can see a spike in voltage when the green LED turns on and then it drops out.  As long as the receiver is on the transmitter, it cycles this behavior.  When I place the receiver EVM on a powermat, the powermat makes an audible beep but there is no led on the receiver.  I checked the tuning caps using a LCR meter and I recorded values that do not correspond to the value that I originally placed onto the EVM.  After further troubleshooting, I noticed that when ever I tried to measure the Caps across C8, C13,  I could not get an accurate reading.  Any insight or ideas regarding the matter would be greatly appreciated.

Thanks

  • 0
    TI__Genius 14890 points

    Jason,

    While researching your recent post, I noticed this one had not been answered.  Is this still a concern or have you moved past this?

    My first thought here is the coil inductance.  You state it is double the inductance of the EVM coil.  I expect that this inductance is too high for the PMA and possibly for the WPC.  Since the bq51221 does power up before it shuts down, using a Qi-sniffer to read the actual commands would give a good answer.  The next alternative would be to look at the RECT voltage.  I suspect it may be going too high.

    Regards,

    Dick