BQ20Z655-R1: Starting with BQ20Z655-R1 and moving to production

Hi Eesu

Yes we recommend you get an EVM to make your process easier. You can also use your own board as long as it is was properly designed and you are able to connect it to the computer via the ev2400.

The steps you need to perform are listed in the attached ppt and summarized as follows:

-perform calibration

-perform chem id identification using gpcchem

-configure the gauge registers

--perform learning cycle.

-Extract golden file

-program on multiple boards

-calibrate voltage current and temperature of each board if neccessary

Battery gauge system design overview-process, flow, tools and configuration.pdf

thanks

Onyx

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Hi
Also, the bq20z655 is NRND, Why are you not using a more recent device like the bq40z50R2?

thanks
Onyx

Thank you very much, Onyx. We have our product with BQ20Z655-R1, designed few years ago. Now it is difficult to change just the fuel gauge. I am just starting to work with this now. BTW, BQ20Z655-R1 is still shown ACTIVE in the product's website.

Few more question:

1. BQ20Z655-R1 is the Flash Gauge, right? Not the ROM gauge?

2. One the slide 4, step (9) says:

"Perform calibration on each unit (this step can be omited if high measurement accuracy isn’t required by using averaged calibration values from 10 boards in the golden file calibration parameters)"

We would like to avoid having to calibrate each device before shipment if possible. Therefore, I would like to know how to generate this averaged golden file? Do I need to run steps 2-5 on 10 different boards with 10 different batteries, and then take the average of all the parameters in Data Flash→Calibration of each setup, and then modify one of them with these averaged calibration values to export the golden file?

One more question:
The calibration setup diagram is not very clear. Or, should I follow "9.1 Calibration of the board if cells are not attached" from SLUA404 for the calibration?

In the application book, it says "Do NOT send the “IT enable” command 0021 before the calibration, because it starts the gas-gauging algorithm with an uncalibrated pack."

My fuel gauge Update Status is already 0x06. Should I disable the IT update?
In the manual it says, "It is recommended to use ManufacturerAccess to enable or disable the Impedance Track algorithm and lifetime data updating." How do I disable IT update using ManufacturerAccess?

Hi Eesu,
pls follow the instructions for calibration of the bq20z655 in the EVM user guide.
You can run calibration even though IT has been enabled. On this gauge once IT has been enabled, it can never be disabled. To disable IT, you will have to program an senc file extracted from a device that has never had IT enabled on it or you can use the default senc file

thanks
Onyx

I am having some problem with calibration. I am using our own board, which is slightly different from the EVM.
I cannot discharge 2A current as suggested in the application book and bqEVSW window. Can I use the charging current which is normally around 1.25A to calibrate the current?