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BQ24314: bq24314

Ian Wang
Mastermind 26745 points
Part Number: BQ24314

Hi Sir,

 I have a question concerning VBAT pin connection to BAT_P or OUT pin of protection IC.

 I saw simplified schematic and pin description that VBAT pin connect to battery pack positive terminal over 100K ohm.

 

 

But from detailed statement for “selection of RBAT” mentioned battery should not be tied to VBAT pin. Can you help to explain and let me know which connection is correct and more stable?  

Thanks, Ian.

  • 0
    TI__Guru 54715 points

    Hi Ian,

    The VBAT pin is used to monitor voltage of the battery for the Battery Overvoltage feature.  If you don't need or want this feature the VBAT pin can be tied to VSS.

    If you want to use the Battery OV feature of the BQ24314 it will need to sense the battery voltage at the VBAT pin, however this should be a sense connection, not a high current connection, and the connection should be made through a large resistor as described in the paragraph shown.  The large resistor will add some error due to the bias current IVBAT, but this is preferred to allowing a low impedance connection if the IC is damaged.

  • 0 in reply to WM5295
    TI__Mastermind 26745 points

    Hi Sir,

    Thanks for information.

    If so, I am confused on the statement of 9.2.2.1. Could you help to confirm what does that mean? Thanks.

  • 0 in reply to Ian Wang
    TI__Guru 54715 points

    Hi Ian,

    It says to use the RBAT resistor.  It would be simpler and cheaper to connect to the pin directly, but it says don't do that.  

    If the part gets melted into a lump but not to GND, IN can get connected to VBAT.  You want RBAT outside to limit the current with its resistance.  A similar thing can happen if you get conductive contaminant on the board shorting the pins.   Contaminants can also short resistors, generally you want a clean board and avoid single faults causing problems.