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TPS65987D: Status Register 0x3F read all 0's after patch file loaded

Don Foong
Expert 4100 points
Part Number: TPS65987D
Other Parts Discussed in Thread: TPS65987,

Hi Team,

Our customer is using TPS65987 for negotiating highest power available from external USB-C charger power source (no USB data, no alternate mode). Before any connection, TPS65987 is in dead battery mode (no VIN_3V3). Can you help with the questions below, thanks in advance.

We are having difficulty detecting whether the device was woken up by a charger attach event.  When booting from "dead battery" with the charger connected, after the patch file is loaded I read the Power Status Register (0x3F) and it is all 0's ( PowerConnection = No Connection, Charger Detect Status = Charger detection disabled or not run, etc). This has our firmware believe that we booted without a cable attached which puts us in an undesired state. Is there a reliable way at startup to detect that the charger is connected without an arbitrary wait time? 

Thanks and regards,

Don

  • 0
    TI__Mastermind 29755 points

    Hi Don,

    Is this a flash or flash-less system? Do you see LDO_3V3 and SPI transactions upon connection? These are basic checks to ensure the part is booting up from dead battery mode when power is provided the first time.

    When you read the register, do you see the I2C transaction acknowledged etc. 

    Regards,

    Peter

  • 0 in reply to pdjuandi
    TI__Expert 4100 points

    Hi Peter,

    The design is using SPI flash (attached schematic). Attached is the pjt file used for the design. (GUI Build version 6.1.1). After VIN_3V3 is applied to the TPS65987D, the system MCU issue the '"DBfg" command to move out of Dead Battery mode. 

    Pls advise is there any step that we could have miss for proper booting from 'dead battery' state? Thanks again.

    Regards,

    Don

      4705.TPS65987DDH_file.pjt

  • 0 in reply to Don Foong
    TI__Mastermind 29755 points

    Hi Don,

    I have tested their configuration on the EVM and I'm able to see the power status register reported correctly.

    See attached slides for more detail.

    Can you verify their setup for the following?

    • Make sure SPI_MISO is really low.
    • Capture the signals like I have shown in the slide, are they seeing similar transition?
    • Capture the I2C transaction with Saleae logic analyzer or its equivalent so we can verify that the transaction is valid when they read the register status.

    The dead battery case is straight forward following the setting of ADCIN1 and MISO pin. As long as the LDO3V3 is up and loading the patch from the flash, it should configure the PD accordingly. Reading all 0s on the register could possibly be wrong format was used or wrong address was sent etc. Are they able to write and read registers in normal mode? 

    TPS65987DH in dead battery mode.pptx

    Regards,

    Peter