BQ20Z655 Fet issue

nathan meyer

I am using the BQ20Z655 on a project that we have prototyped. I am having an issue with the charge and discharge FETs turning off for no aparrent reason. When i first connect cells to the board, i apply a charge to wake up the chip, but it does not turn on the fets. I have to use the Pro screen to manually turn them on. then, if i charge the battery, it works ok, but if i remove the charge it then turns off the DSG FET. Some times, if i can get the DSG fet on, and i discharge the pack, it will turn off the CHG fet if i remove the load. Some times both fets turn back off. I an not seeing any Flags that seem out of the ordinary. I have been through the Data flash and i can not see what may be causing this. Anyone have a thought?

over 12 years ago

0 ThomasCosby over 12 years ago

TI__Guru 73830 points

Nathan

It does not look like you have enabled Impedance Tracking. IT is required for automatic control of the FETs and faults. You should issue a device reset command (41) and IT enable command (21) after the pack had been assembled and the golden file loaded in it. Please try this to see if it helps.

Regards

Tom

0 nathan meyer over 12 years ago in reply to ThomasCosby

Prodigy 150 points

Thanks. I have tried this and now the fets do seem to work properly, however now my design capacity is 0 and the remaining capacity is at 0 and never increases when i charge.

0 ThomasCosby over 12 years ago in reply to nathan meyer

TI__Guru 73830 points

Nathan

Are you using the TI bq20z655 EVM or your own module? Can you extract a .senc file and attach it for review?

Thanks

Tom

0 nathan meyer over 12 years ago in reply to ThomasCosby

Prodigy 150 points

Here is my senc file. after i extracted this my chip no longer will communicate. It now keeps telling me "VB)_T2H_Unknown" and other issue. I can not read data flash or anything now. I was able to reset it , i believe now. I am havin issues attaching the file, since it is a form of an encryptid file, Microsoft will not show it in the folder when i try to attach it.

0 nathan meyer over 12 years ago in reply to nathan meyer

Prodigy 150 points

0815.655_MIT.zip

Here is the file. Still not sure if it is attaching right

0 ThomasCosby over 12 years ago in reply to nathan meyer

TI__Guru 73830 points

Nathan

I reviewed your setup data and found that the Terminate Voltage was set too high. Please reduce it and issue a reset and IT Enable command. The gauge should start reporting capacity.

Regards

Tom

0 Yusuf KAYA over 12 years ago in reply to nathan meyer

Intellectual 630 points

Nathan,

I have sample of BQ20Z655 IC, EV2300 interface and my own module. But i have not found the software BQ20Z655EVSW or BQ34Z651EVSW on TI web site. Can you send the software me to evaluate? My email addresses: yusuf.ky@gmail.com . Thanks in advance.

Power management

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BQ20Z655 Fet issue