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BQ25898: Safety charge time tolerance and IR compensation questions

Randy Chen
Intellectual 2030 points
Part Number: BQ25898

Hi,

Some questions need your help:

  1. We tried to do a charge timer test. REG07 bit[2:1] was set to 12 hr, and stops at 12h 27m, may I know the acceptable variation of this timer.
  2. What’s relation between “IR compensation” and “termination current”? We found that if we set REG08[7:2] = 111111, measured termination current about 1A.(REG05 bit[3:0] was set to 256mA). After we turn off IR compensation, measuring termination current is close to we set. The charging curve is shown as below:

Best regards,

Randy

  • 0
    TI__Guru 54651 points

    1. The safety timer is related to the clock period on the chip. Your measurement is normal.

    2. The IRCOMP setups should follow sction 9.2.7.4 on p24 of the d/s for proper charger operation. Please use appropriate IRCOMP values and try again.

    Thanks! 

  • 0 in reply to Ning T
    Prodigy 40 points
    Hi Randy,

    Did this resolve you IRCOMP/ITERM concern?


    Hi Ning,

    Please clarify how REG08[7:2] = 111111 would not be an appropriate IRCOMP value. This seems like the reasonable choice if the resistance is 70mOhms or higher per 9.2.7.4 on p24 of the datasheet. Also, please explain how/why the IRCOMP value would impact the effective termination current.

    Thank you,
    Paul
  • 0 in reply to user5040560
    TI__Guru 54651 points
    Referring to the d/s, For safe operation, the host should set the maximum allowed regulation voltage register (VCLAMP) and the minimum resistance compensation (BATCOMP) when setting REG08[7:2].
    Thanks!