BQ34110EVM-796: Current sense is inverted, discharging sets the BatteryStatus.CHG bit.

Jeremy Heath1

Part Number: BQ34110EVM-796
Other Parts Discussed in Thread: BQ34110, BQSTUDIO

The current sensing polarity is inverted. Charging is Negative current and Discharging is positive current. I have battery and load (resistor) connected as in Figure 1 of the bq34110EVM Quick Start Guide.

I replaced the bq34111 IC. During charging the BQ34110 [DSG] flag is set and the gauge indicates a negative current in bqStudio 1.3.86. Similarly to charging, discharging incorrectly causes the [CHG] flag to set. When I apply a 350mA load for calibration, specifying -350 mA applied current results in the gauge adjusting to +350 mA.

I do believe I initially set current Positive during calibration, but now when I do calibration with a negative current (and discharging), it will not return to normal. I have tried re-flashing firmware (bq34110_v0_02_build_9.srec) twice; no change.

over 5 years ago

0 Andy Liu (BMS) over 5 years ago

TI__Guru 52115 points

Hi Jeremy,

Are you using a bq34110 EVM? If not, make sure the sense resistor on your board has the correct connection. Also, follow the instructions in the EVM user's guide to do the calibration.

Andy

0 Jeremy Heath1 over 5 years ago in reply to Andy Liu (BMS)

Prodigy 40 points

Yes. Using the b134110 EVM. No changes made to the sense resistor.

Yes. Have successfully completed the calibration and it has not resolved my issue.

0 Andy Liu (BMS) over 5 years ago in reply to Jeremy Heath1

TI__Guru 52115 points

Hi Jeremy,

I have checked my EVM and not seen that issue. This EVM has been used by quite a few customers and I have not heard the same issue.

Please follow the instructions in the EVM user's guide and make sure all the connections are correct.

Andy

0 Jeremy Heath1 over 5 years ago in reply to Andy Liu (BMS)

Prodigy 40 points

I found this to be the same as I am experiencing.

https://e2e.ti.com/support/power-management/f/196/t/654601?tisearch=e2e-sitesearch&keymatch=BQ34110EVM-796

1. Replaced a broken bq34110

2. Used incorrect polarity for initial Calibrations.

3. Charge/Discharge indicators are incorrect.

4. TI could not help resolve the problem.

The post states that the EV board or bq34110 was replaced. Is that TI recommendation?

connected according to Fig 1 of the bq34110EVM Quick Start Guide

0 Andy Liu (BMS) over 5 years ago in reply to Jeremy Heath1

TI__Guru 52115 points

I would suggest trying another new bq34110 device. Don't download the firmware or do the calibration. Just check the discharge current or charge current and see if they make sense.

Andy

0 Jeremy Heath1 over 5 years ago in reply to Andy Liu (BMS)

Prodigy 40 points

Same setup for battery/power supply with resistor as a load. A new bq34110 registers a negative current as a discharge. Charging is a positive current.

So the conclusion is that when doing the Calibration, use a Negative current or else it won't be correctable. A ROM firmware load does not correct this either.

The only option in this case was to replace the bq34110 part.

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BQ34110EVM-796: Current sense is inverted, discharging sets the BatteryStatus.CHG bit.