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BQ77915: Short Circuit delay of 610 usec - Can we make it to trip faster ?

Anil Sudhakaran
Expert 1125 points
Part Number: BQ77915
Other Parts Discussed in Thread: BQ76920, BQ76942,

Hi,

Planning to use BQ7791506   to replace  BMS controller ICs in our existing products. 

Could find from datasheet that Short circuit delay is 400 usec typ and  range is 220 - 610 us.

Based on  short circuit  test experience  from our existing products, we have found that  more 100usec delay,  make the Power MOSFETs to fail.

Any suggestion to take care of this ?  

  * Is there a way we can make short circuit circuit to act faster (100us max) ?

  * Any recommendation on Power Mosfet (30A/30V)  that  can withstand short circuit  for 600 usec.

Thanks in advance for your help .

Regards,

Anil

  • 0
    TI__Guru* 81034 points

    Hi Anil,

    Unfortunately, there is no way to speed up the timing of the BQ77915. You may want to look at one of our battery monitor devices (like the BQ76920 or BQ76942) that offer faster short circuit delay response times.

    For the FETs getting damaged, it may be good to explore using FETs with a higher voltage rating since there can be significant transients with a short circuit event (transients can be double the battery voltage). It may also help to increase the filter component values on the cells to see if you can reduce the transient voltage.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Expert 1125 points

    Hi Matt,

    We are looking for a  cheap standalone IC which can do 4 cell (with cascading upto 24 cells) battery monitoring and protection. Found BQ77915 as the  right  IC except for its high SC delay.

    Both  BQ76920 or BQ76942 need another micro controller  for configuration which will increase cost in our application.

    Please let me know whether TI has any plan to have <100 us SC delay ICs in BQ77915  family soon?

    Thanks & Regards,

    Anil

  • 0 in reply to Anil Sudhakaran
    TI__Guru* 81034 points

    Hi Anil,

    I'm sorry, there is not new device planned for this family soon. 400us is the fastest delay in this device architecture.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Expert 1125 points

    OK Matt.

    Thanks & Regards,

    Anil