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BQ25792: Device not entering OTG mode

Part Number: BQ25792
Other Parts Discussed in Thread: TPS25750, , TPS25751

Tool/software:

I have a design with a TPS25750 and the BQ25792. The board successfully negotiates a voltage when a USB source is plugged in and uses it to charge the batteries. However, it fails to enter OTG mode when the source is unplugged. If I plug in a USB load which tries to negotiate a voltage higher than 5V , the TPS25750 sends an infinite loop of messages (reproduced in table 1) to the BQ25792. There is some slow activity on the SW pins but not proper switching operation.

The messages occur in a loop of this order, but the choice of 1st message is arbitrary.

Reg Val Reg Val Reg Val Reg Val
0x10 0x80      0x16 0xc0       0x14 0x1c         0x10 0x80
0x14 0x1c 0x01 0x0690 0x0d 0x4b 0x14 0x1c
0x11 0x00 0x03 0x0064 0x0b 0x026c 0x11 0x00
0x12 0x00 0x12 0x40 0x12 0x00
0x08 0x08 0x08 0x08
0x09 0x01 0x09 0x01
0x01 0x0690 0x01 0x0690
0x03 0x0064 0x03 0x0064

Thank you

  • Hi William,

    I recall that was some issue with the first version of the TPS25750 firmware.  I have moved this thread to the team that supports the TPS part.

    Regards,

    Jeff

  • Hi William, 

    Thank you for reaching out!

    We recommend using our follow-on device, the TPS25751 for new designs. There are a couple of know issues found in the TPS25750 that are addressed in the TPS25751 specifically with the PD + battery charger pairing. Please see the following FAQ

    Best Regards, 

    Aya Khedr

  • Hi Aya, thanks for the quick response. Is there any workaround for these issues? The TPS25751D is out of stock everywhere I've checked, and I would like to avoid having to redesign to use the TPS25751S as this for a senior design project due in a month.

  • Hi William, 

    Could you please share the json file and schematics? I can take a look to see if there are any workarounds. 

    Best Regards, 

    Aya Khedr

  • Hi Aya,

    I've attached the schematics and configuration json. Thanks for taking a look.

    Fullscreen
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    {"questionnaire":{"version":"7.0.4.7","answers":[0,2,2,1,0,null,1,null,1,null,0,16.8,1,0.04,0.32],"options":{},"configID":"0000","vendorID":"0000"}}
    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

  • Hi William, 

    Thanks for providing. I will look into this and get back to you with some feedback tomorrow. 

    Best Regards, 

    Aya Khedr

  • Hi William, 

    One suggestion I have would be to change the power path for PDO1 to PP3 (PPHV) instead of PP1 (PP5V). 

    Please let me know if you see improvement in behavior. 

    Best Regards, 

    Aya Khedr

  • William, 

    I sent you a friendship request. Please accept this so that we can send a private message. Can help get you TPS25751D material. 

  • Hi William, 

    I will close this thread as the conversation has continued elsewhere. Feel free to open a new thread for further questions.

    Best Regards, 

    Aya Khedr

  • Thanks Adam and Aya for the help and offer, and apologies for my late response. I ended up going with a redesign using the S model since there were other board improvements - and the university paid for expedited shipping ;)