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BQ51013B: Prioritized wireless charging

Fabian Zäh
Prodigy 15 points
Part Number: BQ51013B
Other Parts Discussed in Thread: BQ51013, , BQ25619, BQ25618

Hello everyone,

I want wireless charging to be prioritized, so that charging over the adapter is only possible when no wireless power is transferred.

According to the section 8.3.6 (Adapter Enable Functionality and EN1/EN2 Control) of the datasheet, I set EN1 low and EN2 high.

When both wireless power and adapter is present the output is powered from wireless power, but if wireless power transfer is stopped AD EN is not pulled low, and there is no output.

Any ideas what I'm doing wrong ?

Thank you very much.

  • 0
    TI__Mastermind 23410 points

    Hi Fabian,

    Do you have a schematic we can look over? I'd like to take a look at the whole circuit to help narrow a possible solution.

    Is the adapter ale to power the OUT voltage when wireless power is not present?

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 15 points

    Hi Anthony,

    first of all I want to thank you for your fast reply.

    Yes the adapter is able to power the output when wireless power is not present.

    When EN1 and EN2 are both low, so that the adapter is prioritized, it works. As soon as the adapter is present AD EN is pulled low.

    When EN1 is pulled high and EN2 is low, it also works. AD EN is then pulled low whether or not adapter is present.

    Thank you very much and best regards

    Fabian Zäh

  • 0 in reply to Fabian Zäh
    TI__Mastermind 23410 points

    Hi Fabian,

    Thanks for the schematic!

    Are you able to provide waveforms for the AD_EN pin, AD pin, RECT pin, and the OUT pin when EN1 is pulled high while EN2 is pulled low? Can you also provide one showing a transition where EN1 starts low and then goes high?

    Can you also share more about the current the load is pulling and the adapter you're using?

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 15 points

    Hi Anthony,

    The adapter is a laboratory DC power supply. So this is no problem as I'm only pulling 200mA.

    In this case both adapter and wireless power is present. EN1 and EN2 are both low, so out is powered from the adapter. Than EN2 is pulled high, and the device switches to wireless power.

    In this case both adapter and wireless power is present. EN1 is low and EN2 is high so out is powered from wireless power. Than EN2 is pulled low, and the device switches to the adapter.

    So everything ok here.

    In this case bot adapter and wireless power is present. EN1 is low and EN2 is high so out is powered from wireless power as this has prio. Now wireless power is shutdown, but the device does not switch to the adapter.

    For me it looks like the device is behaving like a BQ51013 as in the datasheet you can read the following:

    I have checked the device marking and it is a BQ51013B.

    Thank you very much for your support !

    Best regards 

    Fabian

  • 0 in reply to Fabian Zäh
    TI__Mastermind 23410 points

    Hi Fabian,

    Interesting, let me reserve some time to spend on this behavior. What is the nature of your intended load? Do you have an MCU that you plan to implement into the design that can control the EN1/2 pins? 

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 15 points

    Hi Anthony,

    the load will be a battery charger (probably bq25618/bq25619) with a LiPo battery with a charge current of around 1A.

    Yes we plan to implement an MCU that will control the enable pins.

    Thank you very much for your support !

    Best regards

    Fabian

  • 0 in reply to Fabian Zäh
    TI__Mastermind 23410 points

    Fabian,

    Awesome, that'll help me better recreate your scenario. I'll take a look at this and get back to you.

    Best Regards,

    Anthony Pham