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BQ25896: Question to enable IR compensation

Herry Chiu
Prodigy 80 points
Part Number: BQ25896

Hi all,

I enable the IR compensation by setting REG08[4:2] to 0x1 and REN08[7:5] to 0x1.

The expected battery CV voltage should be VREG_actual = VREG (4.208V) + min (Ichrg_actual(1800mA) x BATCOMP(20mohm), Vclamp(32mV))

However I observed the battery CV voltage was still same as VREG (4.208V). 

Is any thing I missed to config other register? Or what should I do to debug that ?

Thanks.

  • 0
    TI__Guru**** 166996 points

    Hi Herry,

    The VBATREG register does not change, only the IR compensation register values change.  The final CV value will still be 4.208V.  The charger increases the battery regulation voltage internally so that it stays in CC mode longer.  Once the charger BAT pin voltage reaches BATREG+IRCOMP and the charge current begins to taper, the charge reduces the BATREG voltage back to 4.208V.

    Did you disable WD timer or set to periodically update to prevent expiration?  If not, the registers will be reset.

    To confirm operation, I recommend taking current, BAT pin and battery cell voltage data during at least a partial charge cycle but with IR COMP enabled and disabled.  You should see the voltage at the BAT pin initially exceed 4.208V and then drop to 4.208V at termination.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 80 points

    Hi Jeff,

    I'll do some test and observe the status of charging current/voltage. Thanks for the clarification and suggestion.