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BQ25895: Adding wireless power receiver

Andrew Baek
Intellectual 915 points
Part Number: BQ25895
Other Parts Discussed in Thread: BQ51222, BQ51221, BQ51020, BQ51025, BQ51003, BQ500511A, BQ501210

What's the proper way of adding a wireless power receiver to BQ25895.

For instance, if we are to add a BQ51222 for wireless power receiver,  would we do the following?

  • Connect the "OUT" pin on BQ51222 to the "VBUS" on BQ25895

If we design this way, here are my questions

  • What happens if an external input is connected to VBUS while the wireless power receiver is running?
  • Would this cause a problem?
  • Do we need to add some diodes to prevent the current flowing in a reverse direction?

Is there some reference design to include the following devices?

  • Battery charger, e.g. BQ25895
  • Wireless power receiver, e.g. BQ51222
  • USB input

So far BQ25895 has been working well for our application so we would like to continue to use it.

Thanks again for your support.

Andrew 

  • 0
    TI__Guru* 75976 points
    Hi Andrew
    The bq51221/22 will support USB input using the AD & AD_EN and external MOSFETs, see figure 40 in data sheet also Section 9.3.5. The wireless power is disabled when voltage is applied to AD pin and AD_EN will turn on the MOSFETs to apply voltage to OUT.
    OUT from BQ51221/22 is connect BQ25895 VBUS.

    ***NOTE--The bq51221/22 is a dual mode device supporting both WPC and PMA standard. The customer should review requirements to determine if PMA support is still required. A simpler WPC solution would be the bq51020 / 21.
  • 0 in reply to Bill Johns
    Intellectual 915 points

    Hi Bill,

    Thanks much for your response.

    Yes, that should work.

    A couple of follow-up questions

    Do you have a recommended part for Q1?

    Overall here is what we are trying to do.

    1. Our systems has two devices: a smartphone attachment and a wearable
    2. 5W or 10W for the attachment and <5W for the wearable
    3. For high power receivers, we are considering either BQ51003 or BQ51025
    4. For lower power receiver, BQ51003
    5. For transmitter, can we use a single transmitter with either BQ501210 or BQ500511A?
    6. Is there an advantage to use the higher power BQ501210 when the receiver is limited to either 10W or <5W?

    Lastly would you have recommendations for coils?

    Regards,

    Andrew