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BQ51013B: Wondering about compatibility

David Camp
Prodigy 80 points
Part Number: BQ51013B
Other Parts Discussed in Thread: BQ25101,

Our contracted engineers have used an STWBC-WA Qi digital controller for wireless battery charger transmitters for our wearable tech and we are planning on using the TI BQ51013B for our Receiver IC. What we are wondering is if these two chips will communicate to each other via the backchannel communications and charge properly. Our application will be <5W, so the TI receiver chip should only need to send the ID & Configuration to the STWBC chip in order to get the wireless power to start transmitting. We are also using the TI BQ25101 to charge our Li-ion cell. We are wondering if there will be any issues TI can foresee with talking to an ST chip for charging. Let me know if I need to provide you with any further information or if we can possibly set up a phone call with an application engineer. Thank you very much for any assistance in advance.

  • 0
    TI__Guru* 75656 points

    Hello

    The TI BQ51013B has been WPC 1.2 certified and will work with transmitters that are designed to WPC 1.2.

    ID & Configuration along with others are part of this standard. 

    No know problems with the device.

  • 0 in reply to Bill Johns
    Prodigy 80 points

    Hey Bill,

    Thanks for the quick response.

    If we purchase the BQ51013BEVM to test with our transmitting base-unit, is it possible to replace the coil on this eval board with the TX coil we plan on using with our design? I'd like to test that everything works together with the evaluation boards before we jump to the design. Let me know what you think.

    Regards,

    David Camp

  • 0 in reply to David Camp
    TI__Guru* 75656 points

    Hi David

    The coil can be replaced but TX coil should remain at about 6.3uH for the TX, 5V system.

    The RX coil depending on size should be 10uH to 30uH. 

    Do not recommend swapping the RX and TX coils.

  • 0 in reply to Bill Johns
    Prodigy 80 points

    Hey Bill,

    On that Eval Kit, I assume there is only an Rx coil and we need to provide a Tx coil system to test it. All we really want to do is make sure the BQ51013B talks and plays nicely with our ST Electronics STWBC-WA based Tx board.

    Our Tx coil is a 6.8uH TDK coil, so that should be fine from specifications. TDK WT151512-22F2-ID

    Our Rx coil is slightly below 10uH at 8.32uH but these two coils are meant to work together and play nicely. TDKWR121210-27M8-ID

    If we replace the Rx coil with our coil and use our Tx system to transmit power to the eval kit, will we be able to test that the backchannel communications work at least?

  • 0 in reply to David Camp
    TI__Guru* 75656 points

    Hi David

    I have not tested the two TDK coils together. With a  diameter of 12mm the RX coil is at the edge of what I have worked with.

    Going with the TDK WT151512-22F2, smaller TX will help, closer the ratio of the two coil the better the coupling.

    The problem will be at start up during the ping voltage at the RECT will not increase above UVLO (2.7V) and device will not start.

    "If we replace the Rx coil with our coil and use our Tx system to transmit power to the eval kit, will we be able to test that the backchannel communications work at least?" -- Bill J - Yes

  • 0 in reply to Bill Johns
    Prodigy 80 points

    Hey Bill,

    The UVLO you are talking about is on the evaluation kit correct? This doesn't mean we will have an issue with our design right? All we really want to do is just verify that we can get the STWBC chip on our Tx board to accept the ID & Configuration during the ping stage and begin the wireless power transfer. If we can do that, we know this will work for our design. Does that make sense?

    Thanks a lot Bill for the information and working with me on this.

    Regards,

    David Camp

  • 0 in reply to David Camp
    TI__Guru* 75656 points

    Hi David

    The UVLO applies to the RECT pin, this is operating voltage for the device and also unregulated output voltage.  If the device does not start one on the thing check is voltage at RECT during ping.

    Possible issue with the design is small coil size, 12mm resulting is difficulty starting power transfer.

    The ID & Config should not be a problem.