BQ51052B: Wireless charging does not working.

Hi Abdurahman 

The schematic looks OK.  When you say it does not work could you tell me more possibly send a scope capture of RECT pin at start up.

I am trying to understand what point in the start up or power transfer we have a problem.

Also we have another wireless power + battery charger solution, see Wireless Power Solutions for Battery Chargers

This design will use BQ51013B-Q1 as a 5V power supply and the BQ25171-Q1 and a battery charger.

Similar design can be done BQ51013B (commercial version) and the BQ25170.

Hi Bill,

Sorry for taking so long to reply. There are two pictures of the coil and rect pin under the scope. There is a 37Vpp chirp that occurs every 2 sec and the rect pin is also chirping at 153mV every 2 sec.

Thank you.

COIL                                                                                              PIN RECT

Hi Abdurahman

Thanks for scope capture, this looks like a low power analog ping from the TX to check if RX is still on the charging pad.

Attached is a scope capture of a normal start up with the RX is placed on TX.  When the TX is powered ON or RX placed on TX what do you see?

2604.TX Start up and Comm Packets Guide.pdf

Hi Bill,

The pictures I sent are what I see every moment of charging. I think the IC got stuck when checking if the rx is still on the charging pad. May be there is some problem at the assembly of the coil idk i will check this. Also could you please show me a way how I can fix this problem?

Best regards.

Hi Abdurahman

If the RX send and End Power Transfer (EPT) the TX will stop sending power and will ping the charging pad to see if unit has been removed.

Could be that the RX is send EPT for some reason.

This would be a long packet when the RX is first powered up.

How many units do you see this issue with?

Hi Bill,

I saw this problem at 3 units. None of them work as expected. But prototype 1 is working well as i said. 

TX De-Bug Analog vs Digital Ping.pdf

Hi Abdurahman

See attached.

The TX should send a long Digital Ping (80ms) to power the RX.  Voltage at the RECT pin should increase above 2.7V (UVOL) and RX will try to communicate with the TX.  On the COMM 1 / 2 pin you will see a serial data stream.

The Analog Ping is a very short series of pulse from the TX, on the RX you may see only a slight bump in the RECT by not enough to turn on unit.

Analog Ping is only used to check if RX is present.

Hi Bill,

Sorry for the late reply. I have tested the boards and rect have never risen above 2.7V.

The results are below. I don't know why this circuit doesn't work. Schematics ok, PCB ok but it does not work. Left side is prototype 1 and it works. Right side is prototype 2 and it does not work.

Hi Abdurahman

Does the TX drive the coil with about a 80ms signal to power the RX at start up.  

Do you ever see this?

Hi Brian,

No, I have not seen this signal before.

Hi Abdurahman

The TX should detect the RX is on charging pad and power on for about 80ms so that the RX can reply.  

Applying 6V to AC1 or AC2 should rectify into about 5V at RECT. 

Hi Bill,

I think there might be some issues with the circuit. I did everything that could be done. It seems like some of the chips might be broken. Thank you so much for your help!

Best Regards