STWBC86 stops working after a few days

[S3rr4]

Hi,

I have a array of 2x5 STWBC86 on a aluminium plate to make a charging station for multiple devices. They are all connected to a common 5V source and decoupled by a small filter of Ferrite bead and MLCC.

After testing them for a while i let them rest over the weekend with no devices sitting on the chargers.

After that only a few of the STWBC86 work correctly, the rest doesn't respond to devices. I connected WPStudio and found no errors to be shown but what i found is that the device has its power stage active all the time at its ping frequency.

Best regards

Stefan

 

[willzhou]

Hi 

About " i found is that the device has its power stage active all the time at its ping frequency".

Do you mean, STWBC86  is work on ping phase, even RX is on, it can not charging devices?

It will be nice if you can share below GUI picture to me to get more information.

 

[S3rr4]

Hi,

thanks for your fast reply. 

Yes, RX is active, frequency is sitting at Ping frequency but no charging is happening.

I will have to let it rest over a few days to recreate the issue and take the screenshots.

[S3rr4]

Hi,

i could recreate it within a day.

Please find the screenshot below:

as well see a shot of the mode monitor:

 RX and TX powers values are misleading in correlation to ICUR.

I also looked at the TX Interrupt latches and did find that if i write to "Did not occur" further testing does not alter them wich is different in a Controller not in that "error" state.

[willzhou]

HI 

From your picture, TX get cep timeout, which mean do not get RX Control error packet, So TX will cut off power.

Seems TX/RX communication is bad, What is RX output voltage? Do you use STWLC38-EVK for RX?

How about you adjust TX input voltage, set higher like 6V and try it. 

 

Also you can use GUI and set "TX CE TO MAX" to 10, make cep timeout less to happened.

 

[S3rr4]

Hi,

thanks for the swift reply.

i checked with a scope. the TX is still on (even if RX is removed). This will carry on forever until i reset the controller. Also i guess the CEP is there because of the removal of the RX on the previous charging cycle.

I use an IPhone for testing as well as Ti bq51050b. RX rectifier voltage is perfectly fine (5V) as well i checked the voltage at the VS pin of the TX. (DC-Level and AC component)

never the less will check with higher voltage.

[willzhou]

Based on manual

https://www.st.com/resource/en/user_manual/um3161-getting-started-with-the-stevalwbc86tx-wireless-power-transmitter-evaluation-board-for-up-to-5-w-qibpp-applications-stmicroelectronics.pdf

It maybe tx stuck in fhop feature, change frequency and stay in power-stage mode.

 

[S3rr4]

Hi,

if i understand correctly Fhop is enabled by default.

so you reccomend to disable Fhop feature?

 

Best  regards

Stefan

[willzhou]

yes, i recommend to disable  Fhop feature, attach is cfg for your test.