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BQ25120: bq25120 - continuous VIN_UV

Ricardo Silva53
Prodigy 35 points
Part Number: BQ25120

In the part datasheet it's stated: "V IN undervoltage fault. VIN_UV is set when the input falls below V SLP . VIN_UV fault shows only one time. Once read, VIN_UV clears until the the UVLO event occurs.".

Since I don't have anything connect to Vin I can't understand this fault, but what is troubling my mind is the fact that VIN_UV is not cleared after the FAULT is reported by the INT pin. 

  • 0
    TI__Intellectual 2050 points
    Ricardo,

    If you supply VIN with a voltage, does the fault clear? A voltage less than 3.6V(TYP) on the input is considered VIN_UVLO, so with nothing on the input the device may well be in a constant VIN_UVLO state.

    Also, I would like to point you to section 9.3.7 on page 21 of the BQ25120 datasheet. Specifically this part of the second paragraph:

    "During the VIN UVLO fault, the device sends a single 128-μs pulse on INT, and the STAT and FAULT bits
    are updated over I2C. The FAULT bits are not cleared until they are read in from I2C after the UVLO condition no
    longer exists."

    From this it sounds like the UVLO condition needs to no longer exist AND the register needs to be read for the fault to be cleared.

    I hope this helps!

    -Joe

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  • 0 in reply to Joe Stephan
    Prodigy 35 points
    Hi Joe,

    It looks like we experiencing the problem reported in this thread: e2e.ti.com/.../2117842

    Since we based our design in this reference design by TI: www.ti.com/.../pmp11311
    The noisy Vin exists when we remove the receptor inductor from the charging station in a slowly way.

    We observed the noisy Vin causes the BQ25120 to consume an extra ~800uA, reporting fault and not being able to enter shipmode.

    Do you think the problem is the same as the previously referred thread? Is there any way to reset the device and avoid the high current consumption. So far we could only go back to the normal state by applying Vin and removing it correctly or unplugging the Vbat.
  • 0 in reply to Ricardo Silva53
    Prodigy 35 points
    Just one more thing, it was mentioned by a TI employee that you were planning to release a new silicon "which will address this along with a few enhancements". Do you have already release date?