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BQ4050: Trouble Clearing Safety Bits

Jdog
Prodigy 20 points

Part Number: BQ4050
Other Parts Discussed in Thread: BQSTUDIO,

I am using the BQ4050 in a battery pack and occasionally find that the Short Circuit during Discharge Latch (ASCDL) has been set. (We utilize the Present Pin to reset the Safety Flags, so this bit should be cleared). I connected  a battery pack to BQstudio and observed this bit was set high, I removed the Present pin pulldown and reconnected and the bit was still set high. I commanded a reset using BQstudo and the Bit was still set. I have found that the only way to remove this bit from being set is to send a shutdown command. 

My Question: is there a parameter that is being set that would prevent this from clearing? Is shutting down the device necessary to clear this bit in this case? 

I attached a view of what I am looking at for the problem pack below.

Thanks much

  • 0
    TI__Guru 52115 points

    The ASCDL bit is set because the protection is triggered. I would suggest you not try to clear any safety status bit. Instead,  you should check the conditions that trigger this protection in the TRM and adjust the necessary settings.

    Andy 

  • 0 in reply to Andy Liu (BMS)
    Prodigy 20 points

    First,

    I don't understand what you mean by TRM

    Secondly,

    The latch is set from a short circuit condition during discharge, what setting should be adjusted for this condition?

    The system in which this is used is a dual battery pack system. The packs are monitored with a micro controller and the discharge fets are turned off and on respectively to keep the state of charge as even as possible. One battery dumps into the other if they get two far unbalanced hence the the large current that would trip this bit. Ideally this shouldn't happen but in the case that it does, how is this bit cleared to allow normal operation of the discharge fet.

  • 0 in reply to Jdog
    TI__Mastermind 24870 points

    Hello Jdog,

    The TRM is the technical reference manual. For a short circuit condition, the recovery is in the datasheet, make sure the gauge sees the conditions for an SCD recovery and check if the DSG FET recovers.