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BQ40Z80: Question about AOLD(Overload in Discharge) ?

David Kim2
Genius 3305 points
Part Number: BQ40Z80
Other Parts Discussed in Thread: BQSTUDIO

Short test was conducted on a board with BQ40Z80.

At this time, if you use BQSTUDIO, ASCD(Short Circuit in Discharge) has no response and AOLD(Overload in Discharge) operates.

The phenomenon of MOSFET turning ON/OFF is repeated when AOLD is operated. (ON about 300 ms)

1. Why is AOLD working when it's a short?

2. Is there a way not to turn MOSFET ON/OFF even if it is operated by AOLD?

Thanks

  • 0
    TI__Guru** 105760 points

    Hello David,

    You can change the threshold for AOLD in memory, the TRM section 19.10.10.5 Threshold. and TRM section A.1 Overload in Discharge Protection (AOLD)

    The protections will be set if the voltages values across Rsense are passed. The FETs will remain off until the safety is cleared.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Genius 3305 points

    Thank you for your support.

    I have 2 kinds of boards.

    One is NR=0 and other is NR=1.

    NR=0 is not a problem if you do it the way you told me.

    However, products with NR=1 are equaly ON/OFF of MOSFET phenomenon.

    I think the reason is because LATCH settings are different like below.

    Can you prevent automatic reset even if it's NR=1 of ASCD,AOLD?

    If you know, let me know how.

    Thanks

  • 0 in reply to David Kim2
    TI__Guru** 105760 points

    Hello David,

    Can you explain what you would like to achieve with the configuration? Are you wanting the trip not to clear permanently when the safety is triggered?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Genius 3305 points

    Hi

    The most important goal is not to repeat on/off the output when it is short.

    But now it seems like it's on and off by Reset time.

    Thanks

  • 0 in reply to David Kim2
    TI__Guru** 105760 points

    Hello David,

    Correct, it will get reset after the reset time for each of those protections when the NR = 1.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Genius 3305 points

    Hi

    Can you get rid of RESET TIME even when it's NR=1?

    I told you, I want to eliminate the ON/OFF repetition when it's NR=1 and short.

  • 0 in reply to David Kim2
    TI__Guru** 105760 points

    Hello David,

    So you would like to disable the protection or have the protection never recover once the FETs are turned off?

    You cannot disable the protection because it is hardware, you will need to scale the current or find another means to reduce the voltage across the SRN and SRP pins. I'm not aware of a way to lock the FETs once the protection is set.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 80 points

    Hello Keller,

    we hope it to safer to use.

    if the AUX Pack(NR=0) tripped, the output is shut-off until user re-connect.

    but, Main Pack(NR=1) is different.

    if there were some problems(Short or Overload), every 15s the FET should repeat trip and release.

    I think that can make damage and defect to DSC FET.

    So,

    A. are there other options to set  AOLD and ASCD? I want AOLDL, ASCDL to be set until user take steps.
    B. are there other safety option in short or overload? for example, it can't be release until user act like charging or other behavior.

    Thank you,

    Best Regards,

    Young-Min Bae.

  • 0 in reply to user6013621
    TI__Guru** 105760 points

    Hello,

    The only way would be to set the NR bit to 0, then you can recover a different way. If NR = 1 the gauge will always recover using the timer.

    Sincerely,

    Wyatt Keller