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BQ24196: OCP not recovery at OTG mode

Jeff Chen71
Expert 1345 points
Part Number: BQ24196

Hi,

     In customer's production line they had tested short protection fuction in OTG mode.  The OTG output is from VBUS pin rather than PMID pin.

Test procedure is 

     a) Putting the bq24196 in OTG mode and check the output voltage if correct.

     b) short VBUS pin

     c) Release VBUS pin and check VBUS pin output recovery.

Recently they have some parts could not get VBUS recovery. But I could'nt find any spec say the over current protection could recovery.

My Question is

   a)If short VBUS pin at OTG mode, which mosfet (Q1/Q2/Q3) will turn off first, and how to recovery from protection?

   b)If direct short VUBS pin ,whether or not the mosfet be damage?

   c)Dose OCP fuction  detect bidirection current or just one way? 

Thanks 

B.R.

Jeff Chen

  • 0
    TI__Guru**** 165886 points
    Jeff,

    Regarding a), Q1 turns off. For recovery, the host must rewrite to REG01b4:5 in order to re-enable OTG mode.

    Regarding b), the OCP circuit is in place to prevent damage to the internal FETs.

    Regarding c), if there a short on SYS during charging (current flowing from VBUS to PMID), the cycle by cycle current limit protects Q2 and Q3 and the OCP circuit of Q4 turns off Q4 to prevent damage.
  • 0
    TI__Mastermind 25800 points
    Hey Jeff,

    The difference in the behavior here will depend entirely on your setup. It will all depend on whether the short causes BAT voltage to sag or drop below the BATLOWV threshold, roughly 3.0V. This will depend on whether a real battery is used in this product test, or a power supply with varying input current limits and/or voltages applied to the charger and/or the response time of said input limits.


    Regards,
    Joel H
  • 0 in reply to Joel Hernandez II
    Expert 1345 points
    Hi Joel,
    We had do ABA test at customer side. This issue is follow with chip, I will do the same test in our lab.

    Thanks for your suggestion.

    B.R.
    Jeff Chen