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BQ79600EVM: Design query with USB2ANY

Part Number: BQ79600EVM
Other Parts Discussed in Thread: USB2ANY

Hi Experts,

Good day. Seeking your advise on this design query with BQ79600EVM and USB2ANY (necessity of SPI_RDY and nFAULT pins):

I am trying to interface my micro to BQ79600 eval board over SPI interface, currently I am evaluating the BQ79600 using USB2ANY device, here I see 2 pins on the USB2ANY are used for the purpose of SPY_RDY(J4-2) and nFAULT(J4-4) functionalities. I am trying to evaluate if I can build a system without the above 2 pins, hence I perform the following :-

1.In the user guide I see, if nFAULT pin is not used then I can simply ground this pin, when I tried to do the same on the eval setup I mentioned before, I am unable to WAKE UP and POWER DOWN the BQ79600 device(using BQAutoEval tool and USB2ANY setup), I have removed the 'J13' jumper on the BQ79600 eval board and grounded the nFAULT pin on the same and as for the USB2ANY, I have tried adding a 10K pullup to VIO or just left it floating both of which I am unable to WAKE UP or POWER DOWN the BQ79600 

2. As for the SPI_RDY, my plan is to provide sufficient delays to compensate for the usage of this pin in my actual application but for the time being I tried a similar approach as point 1 in case of SPI_RDY as well, I pulled the J4-2 pin on both BQ79600 and USB2ANY to VIO via a 10K. Even this doesnt seem to work.

Please advice on the above as this is gating HW design and SW development.

Regards,
Archie A.

  • Hi Archie,

    I have seen your message and the team is actively working on this. I hope to have you a reply tomorrow.

    Thanks,

    Geoff

  • Hello Geoffrey,

    Looking forward to your response.

    Thank you very much.

    Regards,
    Archie A.

  • Hi Archie,

    I had the team working in the lab today and we do not see any dependency between NFAULT or SPI_RDY and the ability to wake or communicate with the part. Can you describe your setup in more detail? What kind of supply are you using for the '600? Have you scoped the IC RX line to ensure signal integrity?

    In general I would not recommend designing without these 2 pins. nFAULT is used for signaling the host processor about faulty conditions and while this can be slightly worked around by continuously polling the fault registers this solution will not work for sleep mode. SPI_RDY is being used because of the limited depths to the FIFO and the user needs to read the data to prevent overflows.

    Thanks,

    Geoff