data/text/DLP2/886080

BQ40Z80: 7th cell calibration problem.

Part Number: BQ40Z80 Hi everyone. I have a problem with cell calibration by battery management studio 1.3.86. I set each of 7 cells to 4V on resistors voltage divider. I eter the values for calibration (see attached picture). But I always get 7th cell near 3940mV ad not near 4000mV. All other cells are near 4000mV. Only if I manually adjust VC7 Sense Gain I achieve desired 4000mV at 7th cell. Does anyone had the same problem with calibration by battery management studio 1.3.86.??? Is there any solution to this? I attache 2 gg files with manual and battery studio calibration. bq studio calibration.gg.csv manual calibration.gg.csv

Hello Maxim I'm assigning this to device expert. Expecta response within 2 days.

I forgot to mention when I adjust manually VC7 Sense Gain the BAT pin voltage get adjusted correspondingly but it still inside 1% battery voltage error range. I get the same phenomenon on my design and on evaluation board.

The Cell 7 voltage is handled differently from the voltage of other cells. Let me try my EVM and see if there is a way to help you.

Please try on the test version (1.3.100), I believe this issue should be resolved. Thanks!

I have tried 1.3.100 version of bq Studio. The problem still exist.

Hi Maxim, I guess what you try is to follow the steps in Section 2.2 of the following app note and see if you can have better calibration results. <secret URL>/lit/an/slua868/slua868.pdf Andy

slua868.pdf describe how to calculate the calibration coefficients. I am doing it myself to correct wrong calibration by Battery Management Studio program. My problem is the wrong calibration by Battery Management Studio.

I will report this issue to my software team so that they can double-check if it is necessary to update their existing code. Andy

Do you get the same result in bqStudio if you uncheck "Calibrate Pack Voltage"?