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BQ25731: with 20mOhm resistor

Keith Keller
Expert 7230 points
Part Number: BQ25731

Tool/software:

Hello,

We'd like to increase the sense resistor on the BQ25731 to 20mohm.

Is this possible?  

Or will RSNS_RAC and RSNS_RSR cause a problem?

Thank you, Keith

  • 0
    TI__Mastermind 33205 points

    Hi, Keith,

    Yes, the customer can use 20mohm. The charger does not use the absolute value of RSNS_RAC/RSNS_RSR for IBAT/ISYS/IBUS/PSYS calculation. 

    It leaves for the customer to interpret the readback value, sometime, we need to scale-up or scale-down regarding the current setting or current feedback. 

    However, please keep the RAC/RSR ratio as 1:1, 1:2 or 2:1. This ratio will affect the PSYS calculation. 

    For example, if both RAC=RSR=20mohm, leave RSNS_RAC=RSNS_RSR=10mohm. 

    1A charge current setting (0x0200) *10mohm =0.5A  *20mohm. 

    Programm charge current register 0x0200, now set the charge current to 0.5A. 

    Regards,

    Tiger