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BQ40Z60 pre-charge function available now?

Lankor Liu99
Intellectual 300 points
Other Parts Discussed in Thread: BQ40Z60

Hi, Thomas,

I remember you mentioned that the pre-charge function was not available before (for firmware 4600_0_13 or _15?);  I am wondering when the new firmware will be released.  When I set the Data Flash   NR = 1, EMSHUT_EN = 0 and PCHGBTP=0 (),  the pre-charging does not work.  Then the over-discharged LiPo battery pack can not be recovered using BQ40Z60 which is not convenient.  (I had to plug the LiPo battery pack to another off-the-shelf charger every time).

Thanks,

Lankor

  • 0
    Intellectual 300 points

    It seems that both internal and external pre-charge can not be enabled. BQ40Z60 has not any action even after setting LCHGS = 1 and LCHGM=1  .

    Can someone from TI help me?  Thanks,

    Lankor

  • 0 in reply to Lankor Liu99
    TI__Guru 73830 points

    Lankor

    Pre-charge is broken in the v15 firmware. You will need to set LCHGS and LCHGM to 0. The external pre-charge pin will not enable. You can still use the CHG FET and limit the current with the pre-charge current control setting.

    Tom

  • 0 in reply to ThomasCosby
    Intellectual 300 points
    Hi, Tom,

    In Pre-charge stage, CHG FET can not be turned on. Do you have another way to enable the precharging?

    Do you have the timeline when the new firmware will be released? v15 is released on Jan 2016, 9 months is gone now. It is painful that I have to unplug the LiPo pack every time and use another charger to recover it when it is ove-discharged .

    Thanks,

    Lankor
  • 0 in reply to Lankor Liu99
    TI__Guru 73830 points
    Lankor,
    I am currently out of the office on vacation and do have access to my documents, but I do not recall a selection that disables the CHG FET if the voltage is in the pre-charge range and the external pre-charge is disabled. The CHG FET should remain on and the current limited by the pre-charge current setting. The external pre-charge feature will be fixed with the next firmware update, but will be sometime next year.
    Tom
  • 0 in reply to ThomasCosby
    Prodigy 160 points

    Thomas,

    I am having the same issue that Lankor is having and I can't find the selection you're referring to anywhere. Can you point me to it?

    Thanks.

  • 0 in reply to 1671828
    Prodigy 160 points
    I believe I've figured this out. To get pre-charge working through the CHG fet, you need:
    - LCHGM = 0
    - LCHGS = 0
    - PCGHBTP = 1

    Also, double-check the actual precharge current. In our applicable the nominal precharge current is only 2 counts in the current setting register and there appears to be some nonlinearity that close to 0 - it was only output about 40% of my setpoint. I had to bump up the precharge current setpoint to compensate.
  • 0 in reply to 1671828
    TI__Guru 73830 points
    There is a firmware bug that affects the external pre-charge FET option and also the high resolution pre-charge option using the CHG FET. You can still use the CHG FET in the pre-charge voltage range with the three bits set as you noted.