PFIN fault in bq20z75

Hi Shirley,

Your PFstatus shows that the PFIn bit is being set indicating that the external protection device has blown the fuse due to a fault occuring. Are you using our EVM for this assesment or are you using your board? The FET that triggers the fuse is being turned on, thus pulling PFIN low, so even if you clear the pf as long as Pfin pin is still low due to the external device, ththe PFIN bit being set will keep returning. Check your bq294XX device to see what's causing it's output to trigger the FET that's causing the fuse to blow.

As an alternative, if you do not intend to use this functionality,  you can set the PFIN detect time to zero to turn this feature off.

thanks

Onyx

Hi Onyx,

Thanks for your prompt reply. I'm using  my board actually. Would it be unsafe to turn the feature off?

I have another battery pack with SCD fault after it has been fully charged and been in relaxation for more than 2 hours while I'm running Impedance Track fuel gauge accuracy test as shown in below. May I know the proper method to clear this SCD fault? 

Best regards,

Shirley

Hi Shirley,

The protection features of the gas guage and its peripherals are necessary to ensure safety of your packs. Turning the pfin function off will cause the gg not to detect if the secondary protector triggered due to a fault. Do you have the chemical fuse in your circuit?  I will strongly advice you to check to see the cause of the PFIN being set..Is this problem repeatable accross all boards or it is just one board?

There was a short circuit discharge condition that occured that's why the SCD bit is set. Issuing a command 41 resets the device and clears the safety status register including the SCD.

thanks

Onyx

Hi Onyx,

Thanks for the solution. I'm able to clear the SCD bit now and sorry for the limited information provided because the circuit is not designed by me. However, by referring to the schematic diagram, there is no fuse on the board. Also i do not face this issue on other boards aside from this. I believe it could be due to data flash corruption while i'm programming the default data flash into the chip using bqeasy. After i checked on the .gg file from other battery on hand, i realized the PFIN detect time is actually set to 0.

Would it solve the problem if i reprogram the chip with a fresh firmware?

Thanks.

Best regards,

Shirley

Hi Shirley,

Since Pfin detect time is set to zero, it means that functionality is not needed and the cause of PFIN being set in the pf register is most likely due  to data flash corruption. Go ahead and reprogram the chip with a fresh firmware and let me know  if this fixes the issue.

thanks

Onyx

Hi Onyx,

Thanks for the clarification. I'll reprogram it once i'm done with the learn cycle and get you updated with the status. Apart from this, I'm currently learning on another chip called bq34z100. For this chip, there is an Alert signal which will be generated when fault happens. Will it be cleared once battery recovered from the fault? 

Also I have found a thread about how to update firmware in production using flashstream. Can i use it on bq34z100? I have downloaded the flashstream.exe tool but i'm not sure whether it is usable. Does this file compatible with bq34z100?

FYI, this is the link of the thread which i refer to

http://e2e.ti.com/support/power_management/battery_management/f/180/p/35461/982595.aspx#982595

Thanks.

Best regards,

Shirley

Shirley, 

I am not sure it is compatible. However, I suggest starting a new post with that question so the appropriate experts on that responds to it.

thanks

Onyx

Hi Onyx,

Thanks. I had posted the question in the proper thread for bq34z100 and able to get some feedback.

Here I encountered another issue while performing the learning cycle for bq20z75-v180. The battery capacity has been updated close to the expected value but the update status changed to 0x0A instead of 0x06. Does this indicate the learning cycle has not completed yet?

Thanks.

Best regards,

Shirley

Hi Shirley,

A Update Status = 0A is very unusual. It would indicate that Qmax has been updated two times, the Ra-table has not been updated and IT is no longer enabled. What learning cycle process did you use? Can you describe your process?

thanks

Onyx

Hi Onyx,

The learning cycle process is based on steps in SLUA334B where close Qmax value is known. In fact I have completed a learning cycle previously and obtained a update status of 0x0E. Due to the full charge capacity is unable to reach the value that I set in Qmax, my colleague suggested me to lower the Qmax and re-perform the learning cycle. For the second attempt, I just modified the Qmax pack and update status to 0 without changing other parameters. And I realized i missed out the configuration of Qmax Cell 0~3. Could this be the root cause ? Do i need to repeat the whole  learning cycle process again? 

Appreciate if you could advise me on the proper procedures to re-perform the learning cycle if the first attempt is fail. Thanks.

Best regards,

Shirley