Questions about the BQ2084-V143

Hi Elena,

Sorry for the delay in this response. Answers are inline below.

Regards,

Doug

Hi I have the BQ2084-V143 on the BQ2084EVM-001 board. I have some questions about the Data Flash section of the BQ2084-V143. I have downloaded the software for the bq2084 version 2.1.0. Why is it that not all the fields in the Memory Map on page 49 of the datasheet are programmable with this software? Are the fields that are not in the software constants? I am also looking for further explanation of a few of the fields. 

[DW] In an effort to simplify the design process, we did not include some of the config parameters which were not expected to need tweeking.

Fast Charge Termination and Charge Efficiency  - these are both a percent but a percent  of what?

[DW] Fast Charge Termination is the percent of RSOC that you would like the gauge forced up to when taper termination occurs. This only happens if the CSYNC bit is set. Charge Efficiency is actually just efficiency of the charging process that you expect with your chemistry. Default is 100% because lithium Ion cells do not lose any energy to heat in the normal charging process. If you were charging at a high rate, or using nickel chemistry, the efficiency would be set lower.

Taper Termination Min - is in the software but not in the datasheet

[DW] This is the minimum current needed during the charge taper process to insure that the coulomb counter is counting sufficient charge. Why? This is to inhibit taper termination if the user should unplug the charger.

AFE State Control, AFE Function Control, and AFE Cell Select  - These are not in the software

[DW] These are not meant to be used except perhaps for debugging. See Table 3 and subsequent details in the bq29312a datasheet.

AFE OC Dsg, AFE OC Dsg Delay,AFE SC Chg T/V, AFE SC Dsg T/V, AFE Vref, AFE Fail Limit - bq2048 says these are in the bq29312 datasheet but I don't see all of them described.

[DW] Refering to Table 3 and subsequent details in the bq29312a datasheet:

AFE OC Dsg = OLV

AFE OC Dsg Delay = OLT

AFE SC Chg T/V = SCC

AFE SC Dsg T/V = SCD

AFE Vref - This is the gain of the voltage measurements for all cells. It gets changed in the calibration process.

AFE Fail Limit - This is the number of times that the AFE communication can fail before generating a permanent fail condition.

Cell Bal Vcell Max(Balance Vcell Max) - Don't see mentioned in the datasheet just in the memory map map.

[DW] This is the max limit for the Cell Balance Window to rise up to. It is set by default to 4100 mV.

Hi Doug,

I'm working with Elena on this project and trying to debug our hardware. I'm getting what i think are some unusual responses from the bq2084 chipset and I'm wondering if we have something programmed incorrectly. One example.... the cell undervoltage shutoff seems to be working (DCG FET turns off when a cell goes too low), but i can't get the FET to turn back on when the cell rises above the reset voltage. I can get the FET to turn back on if I powercycle the chipset, so it almost seems like the undervoltage sets a flag that needs to get reset in SW?

I also can't get the CHG FET to turn off when a cell voltage rises too high.

This is a stand series 3-cell li-ion pack... can i send you a screen capture of the bq2084 register set and see if there's something in there that needs to be changed?

thanks,

John