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bq27520-G4 / Powering REGIN from VSYS of charger

S.Satoshi
Guru 21685 points
Other Parts Discussed in Thread: BQ27520EVM, BQSTUDIO

Hi,

My customer plan to connect REGIN to VSYS of charger IC (bq2589x) as attached. The purpose of this configration is to reduce load from battery at ship mode of bq2589x because bq2589x can disable VSYS at ship mode. Then please give your comment for following question.

  1. Can you recommend this configuration? Please let me know if you can find undesirable situation.
  2. Is there no issue to apply battery voltage to only BAT pin at bq2589x ship mode?

Best Regards,
Sonoki

  • 0
    TI__Guru* 76230 points
    is the charger always gonna be attached to the battery gauge IC? I am assuming this is the case as the gauge will need to be powered on by that Regin input pin. I do not envisage a problem doing it this way as long as the max threshold that pin can support is not exceeded.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Guru 21685 points
    Hi Onyx,

    Yes, the charger and gauge will be in system side, so the charger will be attached to gauge. But VSYS will be turn off at charger IC in shipmode though battery voltage is enough high. I think usually REGIN pin is connected to BAT pin and powered from battery directly. So I'd like to confirm if this attached configuration can be recommended.

    Best Rergards,
    Sonoki
  • 0 in reply to S.Satoshi
    TI__Guru* 76230 points
    Regin is just a power supply input to the LDO that powers the chip so i do not see anything wrong doing the connection that way.
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Guru 21685 points
    Hi Onyx,

    Thank you for your comment. Let me ask about different topic.

    I'd like to know which register value will be held when only REGIN is removed. And also both REGIN and BAT are removed. Especially I'd like to know about CycleCount or StateOfHealth such as information of history.

    Best Regards,
    Sonoki
  • 0 in reply to S.Satoshi
    TI__Guru* 76230 points
    Hi Sonoki,
    When the Regin is removed, all RAM registers will be reset. Only flash parameters are kept as is. cycle count is a data flash parameter so that stays and isn't reset. SOH just like FCC and RM is a RAM parameter so that gets reset each time voltage is removed from the Regin pin. BAT pin is just to measure the cell voltage.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Guru 21685 points

    Hi Onyx,

    Can I know which parameters are stored in RAM definitely? I checked TRM and also bqStudio with connecting bq27520EVM but I did not understand it...

    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Guru* 76230 points
    Hi Sonoki.
    Start bqstudio. All the parameters in the register window are stored in RAM.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Guru 21685 points

    Hi Onyx,

    I tried to connect different battery and check the value in resister window. Then Cycle Count shows the same value, it looks the value is not reset. And also Design Capacity shows the same value, it looks the value is not reset. I assumed that these value are reset and change to default value. 

    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Guru* 76230 points
    Hi Sonoki,
    Those don't get reset to default becuase they are contained in data flash. When the gauge is powered on, it initializes and updates the RAM parameters contained in data flash from the data flash.

    thanks
    Onyx