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bq51050B recharge problem

Dusan Mihajlovic
Prodigy 30 points
Other Parts Discussed in Thread: BQ51050B

Dear,

we made a receiver device with bq51050B. We are using it in combination with commercially available charging pads (we have three different brands).

The device is basically functioning correctly. It charges without any problem, both charging pad and receiver device lights up "Charging" LED. After the charging is done charging pad lights up "Full" LED while receiver device turns OFF charging LED. By looking at this behavior everything looks fine, but with further testing we noticed one problem.

We left the device on a charging pad for the whole night and when we got back to the office next morning the charging pad still had "Full" LED light up while the device battery was completely EMPTY. The battery capacity is only 60mAh so after the charging had finished the device started working and it consumed all the power from the battery but the RECHARGE sequence was never initiated.

By looking at the datasheet for bq51050B, the recharge threshold should be in between 4.065V and 4.11V. The only way to initiate recharge sequence is to take the receiver device off the charging pad and put it back again but you can see how this is inappropriate. People like to leave their devices on the charger for the whole night and to pick up the device fully charged in the morning.

Do you have any idea what could be the problem? We looked at the receiver coil with oscilloscope during the WEIRD stage and we can see that transmitter is trying to initiate the communication every 500ms, but it seems that receiver is not responding to this. Still, it's strange that during all of this charging pad is showing Full LED light up. All three charger pads behave the same way.

Any suggestions would be appreciated.

Thanks,

Dusan Mihajlovic

  • 0
    TI__Mastermind 28680 points

    Hi

     

    What the End Power Transfer Packet sent to the Tx?

     

    The recharge depends on the Tx, some recharger after 5min from termination some of them are recharging immediately. What Tx are you using?

     

    Thanks

    Tahar

     

  • 0 in reply to Tahar Allag
    Prodigy 30 points

    Hello Tahar,

    thanks for your reply.

    The End Transfer packet sent to the Tx is 0x01 (Charge complete). You can see the image taken from the oscilloscope on COM1 pin:



    We can see the transmitter tickling every 500ms, so the question is why the recharge is not reoccurring after the battery level falls below the recharge threshold.

    The transmitters we are using are all commercial charger pads from China. But all certified for WPC.

    Looking forward hearing from you.

    Best regards,

    Dusan

  • 0 in reply to Dusan Mihajlovic
    Prodigy 60 points

    Hello,

    We are designing TIs' bq51050B based wireless power receiver and intend to use it with commercially available Qi compliant wireless transmitter/charging pad.

    Is the device is supposed to behave in the above fashioned manner. The recharge sequence doesn't initiate itself.

    Kindly clear the above mentioned thread so that we can proceed with our design.