This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Smaller (diameter) Tx/Rx Inductors using bq500212A chipset

Other Parts Discussed in Thread: BQ500212A, BQ51003, BQ51013B, BQ51050B, BQ51013BEVM-764, BQ500212AEVM-550

I am looking to created a slip ring like device using the BQ series parts but with smaller diameter inductors. I understand that changing the Tx inductor will violate the compatibility spec, but these will be a matched pair, so that doesn't bother me. I need the center to be open-air because an air tube passes through them (part of the application).  That would mean, no solid ground plate either.  Our current constraints look like an OD of 20mm for the inductors and an ID of 10mm.  The thickness can be multiple windings thick.

I guess my general question is, can the BQxxx chipset be used with non standard geometries?  I'm hoping that by leveraging these parts, I don't need to create a custom inductive power transfer circuit.

Alternate chips/solutions are welcome as well.  I'm just starting my search.

Thanks, William

  • William,

    The simple answer is, yes, the bq51 series receivers and the bq500 series transmitters can work with non-standard coils.  As you mentioned, this could make them non-Qi compliant, but that is not an issue for many applications such as yours.

    What are your power requirements?  This could help with suggested devices.

    Regards,

    Dick

  • Hi Dick,

    We are still nailing down the specifics, but it looks like it's around 2 Watts.  We have some electro-mechanical stuff running off this power so that makes it tougher to estimate.

    --William

  • William,

    Understood - it's still early in development.

    The bq51003 is a 5V wireless receiver power supply that is optimized for 2.5W and below applications.  It works quite well with the bq500212A.  If you are over 2.5W, then you should consider the bq51013B.  If you need something besides 5V we do have other options.

    If you will be charging a Li-Ion / Li-Pol battery, then the bq51050B might be a good choice.

    As you get closer let us know if you have questions.

    Regards,

    Dick

  • We purchased the BQ500212AEVM-550 and the BQ51013BEVM-764 dev kits to help us get up to speed on the technology.  The goal was to swap out the existing inductors with coils of our own.  Probably hand-wound at the moment until we find what we want.

    Is there a good reference for creating a coil based on our power estimates and the size of the spool?  Also, we're not limited to the two coils abutting, we can actually have one coil inside the other as long as we have the inner coil hollow.  That should help considerably with the coupling (I would think).

    --William

  • William,

    There are some great resources at:  http://www.ti.com/lsds/ti/power-management/wireless-power-receiver-solutions-technical-documents.page

    In particular, I suggest you read the document under the Application Notes titled "Designing a Qi-compliant receiver coil for wireless power systems, part 1".  It is a very good resource for investigating coils.

    Regards,

    Dick