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BQ24192: Only input current back to default

Jerry Chu
Genius 4915 points
Part Number: BQ24192

Hi Expert,

There are two scenario easy to happen the input current limit back to default. (Only input current.)

1. Charge complete.

2. NTC fault

In the application, it always in VINDPM mode, usual in supplement status, heavy system loading. Does bq24192 has any possible to change input current limit value?

BTW, I saw the block show a FBO, what is it? Thanks!

4848.log.zip

  • 0
    TI__Expert 8230 points

    Hello Jerry,

    The input current limit on the bq24192 is set by the following:

    • After a VBUS plug in event, the device checks the input current limit based on the state of the PSEL and ILIM pins.
    • The host modifies the input current limit via I2C after plug in.
    • The input current limit was set to a different value different than the default, and the watchdog timer expired causing the registers to revert back to their defaults.

    If your application is always in VINDPM under heavy dynamic loads, if the VBUS voltage drops too low, it may trigger a plug in event once the VBUS voltage recovers to normal levels depending on the VINDPM voltage threshold.

    FBO refers to the output of the feedback comparators from the different control loops in the device like VINDPM, INDPM, charge current regulation, voltage regulation, etc that are fed into the converter control.

  • 0 in reply to Fernando Lopez
    Genius 4915 points

    Hi Fernando,

    I measure the VIN drop too low in last case. But I also met a new case and VINDPM setting is low than Vbat but the Vbus didn't drop too low, also got ILIM go back to default. Can you help to check it? Thanks!bq24296M test.pptx

  • 0 in reply to Jerry Chu
    Genius 4915 points

    Hi Fernando,

    If your application is always in VINDPM under heavy dynamic loads, if the VBUS voltage drops too low, it may trigger a plug in event once the VBUS voltage recovers to normal levels depending on the VINDPM voltage threshold.

    I think the case is VINDPM issue. As your mention, what's the trigger voltage point or range? Thanks!

  • 0 in reply to Jerry Chu
    TI__Expert 8230 points
    Jerry,

    You can find the VINDPM threshold on REG00[6:3].
  • 0 in reply to Fernando Lopez
    Genius 4915 points

    Hi Fernando,

    I know it can adjust the VINDPM threshold, as the attached file, the difference VINDPM can get difference result, but both are reach to VINDPM threshold.

    What's the trigger input current limit condition? Thanks!

    3660.bq24296M test.pptx

  • 0 in reply to Jerry Chu
    Genius 4915 points
    Hi Fernando,

    If the VINDPM sets to 4.2V and charged done. If the Vsys got a high loading, the input current will change to default. Can you help to explain it? Thanks very much!
  • 0 in reply to Jerry Chu
    Genius 4915 points
    Hi Expert,
    Someone can help it? Did I trig any voltage to reset the current limit? Thanks!
  • 0 in reply to Jerry Chu
    TI__Mastermind 25800 points

    Hey Jerry, 

    So that IINDPM setting is resetting when you apply a heavy load. 

    Is VINDPM triggered? Did you look at the VBUS voltage? Do you the same thing happen if you increase the VINDPM threshold to something like 4.4V or 4.5V?


    Regards,

    Joel H

  • 0 in reply to Joel Hernandez II
    Genius 4915 points
    Hi Joel,
    If my battery voltage is 4.38V and the VIN down to a level, maybe 4.4xV, the charger can't switch to such high duty cycle, the current will be reset to default.
    If that's true, I can't find any information in datasheet, you can help to check it?
  • 0 in reply to Jerry Chu
    TI__Mastermind 25800 points

    Hey Jerry,

    So this is indirectly described in section 9.3.1.3.1 REGN LDO where we talk about requirements to start the LDO and then the converter. 

    In this section, there is a reference to VBUS > VBAT + VSLEEPZ.

    If this requirement is not met, you may likely see the following happen:

    1) Converter shuts off

    2) Load current removed/supplied by battery

    3) Unloaded VBUS rises > VBAT + VSLEEPZ

    4) REGN turns on and /PG

    5) Input detection restarts (sets to default state)

    6) Converter restarts with default VINDPM

    Understand as well that the there are two thresholds for VSLEEPZ. In this scenario, the falling threshold is most critical, which can be as low a 35mV.

    Regards,

    Joel H

  • 0 in reply to Joel Hernandez II
    Genius 4915 points
    Hi Joel,
    Thanks very much. May I know how to trig the item6? Because in my application, I didn't get VINDPM changed. Thanks!
  • 0 in reply to Jerry Chu
    TI__Mastermind 25800 points
    Hey Jerry,

    You are correct. Item 6 will only occur if there is a complete POR of the charger.

    Regards,
    Joel H