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BQ76930: BQ76930 : why Rf is connected to BAT+

Laker Lian
Intellectual 290 points
Part Number: BQ76930

HI,

I doubt : why is there a diode here, and there's a resistance Rf there ? I think Rf and Cf are redundant.

Can you explain why Rf is connected to PACK+(BAT+)

Thank you!

  • 0
    TI__Guru 54715 points

    Hi Laker,

    Rf and Cf are the power filter components for the BAT supply pin for the IC.  These are required to provide a stable voltage and power the IC.  See section 9 of the bq76930 data sheet.  The diode circled is to avoid damaging conditions during transients.  See the application note bq769x0 Family Top 10 Design Considerations  figure 20.  If Rf is removed power supply current will flow through the diode during normal operation loading VC10 and altering the voltage measured for that cell.  Note that the VC5X power pin also requires Rf and Cf filter components for proper operation.