• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 64 subscribers
  • Views 414 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25180: No VSYS after hardware reset if battery only

Michael Hagmann
Prodigy 60 points
Part Number: BQ25180

I configured the BQ25180 to do a hardware reset after long button press of 10 seconds and a auto wake up timer restart of 2 seconds.:
TMR_ILIM = 0x56
If I do a reset with battery and VIN present, everything works fine.
But if I do a reset with only battery without VIN present, the voltage at SYS does not get enabled properly afterwards.
I can see a short voltage pulse of about 2V after the reset, but it gets disabled again immediately.
If I then enable VIN, VSYS gets enabled as well.
I don't think that it is because of an overcurrent, because I can see no hiccup mode.
What else could be the problem if VSYS does not get enabled after hardware reset with battery only?

Thanks and best regards

Michael

  • 0
    TI__Mastermind 23350 points

    Hi Michael,

    Can you provide a waveform of the 2V pulse that you're seeing? This sounds like it's well above the system short detection but I'd like to confirm this.

    Can you provide some information about your load at SYS?

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 60 points

    Hi Anthony

    Thank you very much for your answer.

    You are right, it is because of battery overcurrent protection. I have a 680uF capacity on VSYS which seems to produce a current higher than 1A. If I remove this capacity, the voltage on VSYS stays stable after the hardware reset.
    Seems like I have to add some current limitation for this capacity in case of a hardware reset.

    Thank you very much.
    Best regards
    Michael

  • +1 in reply to Michael Hagmann
    TI__Mastermind 23350 points

    Hi Michael,

    Yeah, that's quite a lot of capacitance on the SYS pin. By default, the Battery OCP is configured for 1000mA, have you tried setting it to 1500mA? Otherwise, you're correct in that you'll need a current limitation to help with this behavior.

    Best Regards,

    Anthony Pham

  • +1 in reply to Anthony P Pham
    Prodigy 60 points

    Hi Anthony

    Because the capacity is on VSYS directly and the registers of the BQ25180 get reset to default values during hardware reset, I have no chance to set the current to 1500mA.
    I think I will add a current limit resistor in series which I can bypass by software as soon as I need the capacity.

    Thank you for your support.
    Best regards
    Michael