• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 64 subscribers
  • Views 235 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

BQ25570: Does the VBAT_OV Accuracy include VBIAS variation?

Nicholas Carley
Genius 9965 points
Part Number: BQ25570

Hello,

I'm checking tolerance on the battery overvoltage protection on the BQ25570, and see a VBAT_ACCURACY "Overall accuracy for threshold values VBAT_OV, VBAT_OK". Does this +/-2% value include the VBIAS variation, or should I also take that into account in my tolerance analysis as an additional source of error?

Thanks,

Nick

  • 0
    TI__Guru**** 167116 points

    Hi Nick,

    No.  Please include both the VBIAS variation and the VBAT_ACCURACY variation for overall accuracy computation.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 185 points

    Hi,

    we included the variation for overall accuracy computation and for most of our manufactured devices the voltage stays within the limits, but near the upper limit (we're performing 100% measurements on V_STOR).

    Out of >8000 measured devices we are observing that the median of the voltage is not located around the typical value but 2.0% higher.

    For setting VBAT_OV we're using 1% resistors with 1M (ROV2) and 560k (ROV1). This should lead to 5.056V (typ.), 4.872V(min), and 5.254V(max).

    Is this behaviour known for this IC or do you have any suggestions/ideas why this happens?

    Thank you,

    Reinhard

  • 0 in reply to Reinhard Koeppner
    TI__Guru**** 167116 points

    Hi Reinhard,

    I am not aware of an IC issue.  However, as explained in the d/s layout section, residual solder flux during assembly can create a parasitic resistor that alters the BAT_OV and other resistors so that the thresholds are off. Other customers have reports this issue.  We even had to find another vendor with higher quality cleaning equipment in order for the TI EVMs to meet spec.  If you remove, clean and replace the resistors on the failing boards, do they pass or do you have to replace the IC itself (of course replacing the IC may add or remove solder flux)?  For debug, you might try standing the resistors on their edge to reduce surface area for the parasitic resistor.

    Regards,

    Jeff