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BQ51050B: Issue completing handshaking to initiate consistent wireless power transfer with Qi Transmitter

David Camp
Prodigy 80 points
Part Number: BQ51050B
Other Parts Discussed in Thread: BQ51003

I have a design that uses the STWBC-WA on the wireless power TX board and a TI BQ5105xB chip on the receiver side and I'm having a hard time getting the handshaking and charging to work. I am using the STEVAL-ISB045V1 with the Tx coil swapped out with the coil we are using for our design. I have got it to briefly work and apply a arge, but can not get it to work consistently. The error code appears to be CONTROL_ERROR_TIMEOUT which is causing the three rapid blinking lights to restart the Qi handshaking process. I have got it to work briefly by tweaking some of the configurable parameters on the STWBC chip via the STWBC GUI 3.48 software, but I'm looking for any specific guidance regarding a CONTROL_ERROR_TIMEOUT and what settings might affect that. Both chips are Qi compliant and when we did get the power transfer to initiate, we were able to see the Manufacturer show up as TI from the receiver, so that is working correctly. I'm trying not to tweak too much as I'm not sure what can damage the boards. I can provide the schematics if that helps.

The error codes and their details from the datasheet are as follows (we are seeing CONTROL_ERROR_TIMEOUT):

These are the configurable parameters we have to work with:

Our TX coil: TDK WT151512-22F2-ID

Our RX coil: TDK WR121210-27M8-ID

https://www.st.com/en/power-management/stwbc-wa.html

Any guidance with how to resolve this error would be greatly appreciated and I can provide more design files as necessary.

 

  • 0
    TI__Guru* 75786 points

    Hello

    I problem could be unit not tuning to the correct operating point, RX is asking the TX to increase (or decrease) power and it is not responding.

    Take a look at the RECT pin of the RX, you should see the control error packets(CEP) riding on a DC level?  The TX will decode the CEP and DC level will change.

    If the TX is not decoding the CEP level will not change.  The CEP are sent every 250mS even if no adjustment is required.  If there is a large error packets are sent every 30mS.

    Another possible problem is the TX cannot go high enough in power to support the load.  Check operating point of the TX. 

  • 0 in reply to Bill Johns
    Prodigy 80 points

    Hey Bill,

    Thanks for the reply. The TX must be decoding the packets to a degree because we did get the power transfer to work for about ten minutes at one point. The ST chip is for applications less than 3W. What dictates the DC level the RX is requesting from the TX? I assume the RX communicates to the TX what it is looking for in terms of a setpoint to charge and the TX attempts to match that. I'll include a screenshot of our schematic here.

    How do I know what the operating point of the TX is? Here is what it seems like are the operating conditions for the STWBC-WA

    Is there anything we can do regarding the settings or if there is an issue will this be some component changes? It seems promising that we were able to get the power transfer to work for about 10 minutes. I really appreciate your help Bill.

    Regards,

    David Camp

  • 0 in reply to David Camp
    Prodigy 80 points

    Hey Bill,

    Is it possible to use the bq5105xB Dynamic Rectifier Control to charge an LIR1220 battery at roughly 10mA? That would require a higher VRECT correct? What would our RILIIM, RFOD, and RTERM resistor values need to be for this? I'm having a bit of trouble following the datasheet math on this. The BQ51003 talks a bit more in-depth about Dynamic Rectifier Control, but the BQ5105xB does say it is present in that device. Is there any chance we could set up a brief phone call to discuss if we can use either of these chips for our application?

    http://www.ti.com/lit/ml/slyt570/slyt570.pdf

    Regards,

    David Camp

  • 0 in reply to David Camp
    TI__Guru* 75786 points

    Hi David

    We are working this problem off-line and I will close this post, can open later if needed.