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BQ25713B: OTG re-enable sequence

David Mckinney
Expert 6860 points
Part Number: BQ25713B

Hardware setup: BQ25713B on our board, TI EVM has non-B version. 

 

On the first activation of OtG (after applying battery voltage and programming the applicable OtG registers) on our board is successful just as it's on the EVM board getting VBus at 5.004V and being able to load it to close to 2A as programmed.

 

The OtG mode is then turned-off by either setting the En_OtG bit (#4@Reg. 35h) low or alternatively making the OtG_VAP (#5) pin low and VBus appropriately drops down to 0V.  However our predicament is that whenever we restore the En_OtG bit or OtG_VAP (#5) pin back to high (whichever was a low), VBus is not restored back to the 5V, stays at 0V.  The only way to get VBus back again is to set the OtG_VAP_Mode (#5@Reg. 34h) bit low or remove battery power and start register programming all over again.

 

Any ideas why our board behaves differently from the EVM in this respect?

  • 0
    TI__Mastermind 25800 points
    Hey David,

    Can you describe the test setup a little more? What is the battery voltage? is the 2A load always applied at VBUS, or only after the first successful OTG startup?

    Do you also have a schematic of the board? How is the configuration of the custom board different from the EVM?

    Do you have the register settings and reads of status registers before and after each event (register dump before and after successful startup, and register dump before and after the unsuccessful re-startup)?


    Regards,
    Joel H
  • 0 in reply to Joel Hernandez II
    TI__Expert 6860 points

    The applied battery supply voltage is 8V on both the EVM and our board.  The OtG Voltage (06h) and Current (08h) registers are programmed respectively to 5.004V and 2000mA.  Both boards are being driven by the studio SW.

    I am working on getting a before and after register load dump.

  • 0 in reply to David Mckinney
    TI__Mastermind 25800 points
    Hey David,

    A schematic will help as well to compare to the EVM.


    Regards,
    Joel H
  • 0 in reply to Joel Hernandez II
    TI__Expert 6860 points
    Issue isolated to HW problem. Found this morning that the issue on not being able to toggle OtG back on (in OtG mode, not VAP mode) was caused by an accidental severance of the top side of our R971 "top" resistor (EVM's R19) ILim_HiZ divider from its RegN power source (0Ω jumper R1835). Troubleshooting/continuity checks revealed that indeed R971 became electrically detached from R1835.