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BQ76200: Current flowing through the PACK pin

Mike Mrazik
Expert 1255 points
Part Number: BQ76200
Other Parts Discussed in Thread: BQ78350-R1

Hello,

What should the current be flowing through the PACK pin on this part?  The datasheet states what the current is for the BAT pin, but I didn't see anything on the PACK pin.

See above, only shows the shutdown current for BAT and PACK pin.  

Thanks, Mike

  • 0
    TI__Guru 54715 points

    Hi Mike,

    There is not a characterized current into the PACK pin.  It is generally much less than the BAT pin, however in certain modes it is large.  See http://www.ti.com/lit/pdf/slua794 figures 7 and 8. 

  • 0 in reply to WM5295
    Expert 1255 points

    Hello,

    That is what I am seeing, what are the causes for it being large?

    The BAT pin I'm seeing pulses every 25mS, which averages to about 50uA of current.

    The PACK pin I'm seeing pulses every 250mS, which averages to about 205uA of current.

    Any suggestions to reduce?  I saw Figures 7 and 8, I'm not using PCHG at all so I'm floating that pin and the PCHG_EN pin.  PMON_EN is connected to the "VEN" pin of the BQ78350-R1.  I have the PACKDIV pin connected to NOT-STUFFED resistor divider because I'm not using it.  There is no path to ground to draw current, is there an additional one inside? 

    Thanks,

    Mike

  • 0 in reply to Mike Mrazik
    TI__Guru 54715 points

    Hi Mike,

    Normal I(BAT) shown in the data sheet is 40 uA typical, so your 50uA seems in range.  Current and pulse frequency will depend on the load on the FET gates.

    The pack pin current will depend on the inputs.

    PCHG_EN has a pull down internal, so floating is OK, pulling down may be better since you know nothing couples to it then.

    PMON_EN connected to VEN is likely the cause of your PACK current pulses.  VEN is a periodic signal.  Even with PACKDIV open the part draws significant current internally from the PACK pin to bias the internal switch.  Most of the current is in the switch biasing, the current out PACKDIV is small.