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ASCDL overload bit, Reg write fail

Calino Perez
Intellectual 550 points
Other Parts Discussed in Thread: BQ76930, BQ78350

Hi,

Please help with the following situation:

Status:

  • Configuration: 10 cell, multi-meter measured 40V+
  • REGSRC ~16V, OK
  • REGOUT 2.5V
  • Can read SBS commands, registers

Problem

  1. ASCDL, ASCD, AOLDL bits show over overload errors.
  2. Write fails: Even after “unseal_full_access” command, cannot see any change reflected when “scanning” registers when doing {FET_EN, LF_EN, toggle DSG, toggle CHG, etc.}.
  3. Between TS2 and VC5X we have a fixed 9.75kohm RES connected, but TS2 showing negative value.
  4. Tested with three new bq76930’s, and one old unchanging bq78350, all show same problem.

Which part of the circuit problem could have caused this?

Calino

  • 0
    TI__Guru 54715 points
    The gauge status shows short circuit and over current: ASCDL, so short circuit happened multiple times; ASCD; AOLDL so over current has occured multiple times; and OCD so current has persisted for some time. The current reported is -16.7A which is a discharge current polarity. A current mis-calibration could cause a false current report but the ASCD and AOLD come to the gauge as a status, so it is probably a real phenomena. It may be an unexpected current flow or unexpeted positive voltage on SRN of the bq76930 or negative voltage on SRP.
    The TS2 pin will normally read about 0V with respect to VC5X. If the gauge is configured for external temperature measurement (default) TS2 will pulse high every 2 s, you will likely need an oscilloscope to check. If you read with a meter you may see a pulse, if you see a negative voltage the bq76930 may have an XREADY fault and the gauge may have a permanent fail for that fault. You show cell voltages on cells 6-10 though so that seems unlikely. Probably the measurement is operating but the gauge is configured to ignore it since the value reported for TS2 is the same as TS3 which does not exist in the bq76930. Check the bq78350 TRM for how to configure the temperature sensors in Data Memory. If you need assistance with parameters once any hardware issue is resolved the gas gauge experts will be more knowledgable. We can get the post moved or you can ask in that forum.
  • 0
    TI__Expert 6085 points
    Calino,
    check if there the recommended caps installed on the schematics. typically there is also a 4.7uF cap from TS2 to VC5X; 1uF from CAP2 to VC5X;