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BQ2970: Can the BQ2970 monitor voltage across the FETs during an over-current event?

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Part Number: BQ2970

Hi,

I'm posting this question on behalf of my customer.

I am considering using the bq2970 protection chip on an up-coming battery project. The battery may deliver current pulses higher than the over current discharge but only for a fraction of a millisecond, less than the OCD trip time. I do not want the OCD to trip for this known pulse. The concern is if two high current pulses 20ms apart could accidentally trip the protection.

I wanted to verify, during an over current event, does the bq2970 continually monitor the voltage across the FETs? (Instead of only checking on the voltage at the start and end of the over current delay time)

Thanks!
Lauren

  • Hi Lauren,

    The device's behavior during over current discharge is described in section 9.4.4 of the datasheet. For this fault to be triggered, the difference between the V- pin and the VSS pin has to be greater than Vocd for a time longer than the discharge over current delay. This delay value is programmable and can be 8 ms, 16 ms, 20 ms, or 48 ms. If the fault only occurs for a fraction of a millisecond, the fault should not trigger. Even if the two faults happened at exactly 20 ms apart (if that is your programmed delay), I doubt the fault will trigger. 

    Thanks,

    Shawn

    TI provides design resources and design advice (including technical, schematic, code and/or system review) “as is” and with all faults.  All information in this or related correspondence is provided subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).

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