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BQ40Z50-R1: Activating PTC function

Ravid BY
Intellectual 330 points
Part Number: BQ40Z50-R1

Hi,

I am having some troubles with the PTC function.

When activating the PTC function and heating it up to 200c it will not disconnect the DSG&CHG fets (The PTCEN pin short to BAT and PTC type used same as in the application schematic).

The commands I send to activate it are:

PF_EN=1

Settings - Permanent Failure - Enabled PF C - PTC=1

After configure the above and sending a RESET command, the PF flag in Operation Status A is set and DSG&CHG fets are disconnected (XCHG&XDSG=1).

I don't understand what I'm doing wrong.

Appreciate your help.

  • 0
    TI__Guru* 76230 points
    based on your description, it appears that the gauge algorithm has determined that the fets should turn off since xchg and xdsg are set but are you saying they aren't turning off? why do you think they aren't turned off? I suggest you measure the gate voltage on your fets to make sure that is the case. FYI permanent failures are not designed too be recovered from except you input the pf clear keys.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Intellectual 330 points

    Hi Onyx, I didn't say that the FETS aren't turned off.. They were turned off, but I don't understand why the PTC protection was activated.

    Can you please explain how to activate the PTC protection? (maybe I'm doing something wrong)

    Thanks

  • 0 in reply to Ravid BY
    Expert 2475 points
    Ravid,
    Your description sounds like up have the PRF18BA103QB1RB PTC installed in the circuit and are questioning why the FETs are disabled and the fault is declared after heating the pack to 200C. Is this correct? The PRF18BA103QB1RB PTC is designed to trigger after the temperature exceeds about 130C, so this performance would be expected. If this is not what you are trying to communicate, then please clarify.
  • 0 in reply to TEC
    Intellectual 330 points

    Hi TEC,

    Thanks for the replay.

    I will try to clarify.

    1. The PTC on my board is connected exactly like in the application of bq40z50-r1.

    2. I tried to heat the PTC up to 200c, in order to see if it will disconnect XCHG&XDSG fets. It was not working!

    3. I thought maybe I have to activate the permanent failure protections by setting PF_EN to 1, but it was also not working (the PTC protection was not working while heating it up to 200c).

    4. Another thing I did is to set Settings -> Permanent Failure -> Enabled PF C -> PTC to 1 - but it also was not working (the PTC protection was not working while heating it up to 200c).

    5. I tried to send RESET command after doing sections 3 & 4 above and when the gauge was waking up from reset the PTC was tripped and XCHG & XDSG were turned off (without heating the PTC at all).

    I hope it is more clear now.

    Thanks

  • 0 in reply to Ravid BY
    Expert 2475 points
    I would agree that the FETs should have been disabled without the reset.

    The PTC is a hardware based protection feature, so the PF_EN and Enable PF C settings should not prevent it from taking action. Are you using the PRF18BA103QB1RB PTC? You could try pulling the PTC pin to VSS to see whether this will trigger the protection without having to heat up the module. TI may have to inspect and bench test your srec file to identify the problem.
  • 0 in reply to TEC
    Intellectual 330 points

    Hi TEC, Yes I'm using the PRF18BA103QB1RB  PTC.

    I tried to short PTC pin to VSS but still not working (while PTCEN is short to BAT).

    Are you sure that there is no need to configure the BMS in order to activate it?

  • 0 in reply to Ravid BY
    Expert 2475 points
    I am not aware of any firmware configuration requirements to enable the feature. TI may have to inspect and bench test your srec file to identify the problem.