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How the VFC works in the bq2060a-e619

J.C Chen
Expert 1285 points
Other Parts Discussed in Thread: BQ2060A

Hi:

     I  have look for the VFC in the datasheet of bq2060a, Howerver , there is no mention of  the details.

     1. How about the VFC get Vdd from? Can anyone give me the block to decript it??     If the external JFET  generate a wave drift about 30mV.(Vcc is in the range of 3.1-3.5),  does it will affect the VFC frequency?

     2. Does the external capacity in bq2060a will affect the VFC work. for capacity venting?    

        2.1) One sample, I calibrate the VFC in the alternate mode, VFC value increase while i continues re-calibrate the battery... I am very sure i have correctly calibrate the voltage. If apply a discharge current to the battery. several minutes later, re-calibrate the battery  VFC in the alternate mode, The VFC value is very small with 100(100 in dec).        What could i to do futher???

  • 0
    TI__Expert 6470 points

    Hi J.C.,

    Not sure I understand these questions completely. I have attached a couple of app notes for the bq2060a, one covers VFC offset and the other has a section on calibration of VFC gain.

    1. No, sorry there is no block available. It is normal to see 30 mv pk-pk ripple on Vcc. It does not affect the operation of the VFC.

    2. Sorry, don't understand your terminology here. "external capacity" and "capacity venting" are not in my vocabulary. Maybe you can rephrase it?

    3. Not sure of the question here. If you use the Alternate method, be sure that absolutely no current is flowing through the sense resistor.

    bq2060_Cal.pdf
  • 0 in reply to Doug Williams4811
    TI__Expert 6470 points

    Looks like the forum only accepts one file attachment per message. Here is the other app note.

    slva151.pdf
  • 0 in reply to Doug Williams4811
    Expert 1285 points

    Hi

       Sorry for few vocabularies..English is not my first language."Capacity", the right form is capacitance....

        The capacitances connected the pins SR1 and SR2, if any capacitances has leakage or other capacitances use in bq2060a,  should that effect the VFC correctly??  

        The problem "remaining capacity jump" has existed for about two mothes..It's urgent to solve..

        Best regards