P9242-R Wireless Charger not working

Hello,

I'm having trouble with my P9242-R based wireless charger that I designed for a client. The chip in question is this:

https://www.idt.com/us/en/products/power-management/wireless-power/wireless-power-transmitters/p9242-r-wpc-122-compliant-wireless-charging-transmitter-15w-applications

I used the exact same circuit given in the official datasheet. Followed the layout guidelines.

The issue I'm having is that the board powers on, green LED flashes for a second, then the red LED starts flashing at 4 Hz indicating a fault.

I tried getting the status register value via i2c bus and it seems like it's indicating a "over temperature fault". The problem is I kept getting different values while trying to read the status register via i2c. But the number "6" kept coming up which might indicate the temperature fault according to the datasheet.

Upon further investigation, I also found the Q6 FET to be insanely hot to the touch. I replaced the FET, and yet the new FET continued to be super hot to the touch. I checked for shorts but couldn't find any. The Q6 FET is indicated in the picture below.

Any help would be appreciated! Am I missing something?

Parents Reply
  • Hi,

    1.  Can you read 0x6E0 and 0x6E1 when the issue occurs?

    2.  Does it happen when  the Tx is in power transfer or not in the power transfer?

    3. What is the voltage level of TP314 (pin 30 (TS))?

    4. Can you probe TP327 (SW_BRG2) and TP507 (gate of T504) in 1s/div?

    5. What is the FW version?

    1. 0x6E0 is showing 0x02 or 0x04; 0x6E1 is showing 0x06
    2. It is happening during power transfer
    3. Voltage level is 2.1V after initially triggering over-temperature at 0.6V
    4. See attached image. Red is TP327, blue is TP507  
    5. FW version is major 0x06 minor 0x18
Children
  • Hi Cwern,

    1. What is the Rx used to test the Tx?  what is the load current of the Rx when the issue occurs?
    2. What is the Tx coil part number?
    3. Can you measure the temperature at the thermistor when the over temp shutdown is triggered?
    4. Can you probe below signals before the power transfer until the over temp is triggered?

                    TP314(TS), TP306 (LDO33); TP505 (coil1); Input current of the Vin+ and Vin+

    1. I can't open the layout.  Can you send me the PCB layout in PDF (similar to the section 5_Board layout in the REN P9242-R EVK User Manual)?

    Thanks!

  • Hi,

    sorry for the late response.

    1. Rx used is P9415, issue is independent of load current
    2. Tx coil is custom
    3. Voltage at the pin of the thermistor is dropping below 0,6V when error is triggered (temperature is also high at this moment, for testing I used a hot air soldering station). After the temp shutdown voltage at temp pin is returing to normal value
    4. See attached image, Channel 1 is TP314, Channel 2 is TP3069, Channel 3 is TP505, channel 4 is Vin+ 
    5. See attached PDFs

    20914_IndiumTx-01B_Top.pdf 20914_IndiumTx-01B_Inner2.pdf 20914_IndiumTx-01B_Inner3.pdf20914_IndiumTx-01B_Bottom.pdf