BQ2060A: Unable to retrieve temperature accurately.

Ashley DaSilva

Part Number: BQ2060A
Other Parts Discussed in Thread: BQSTUDIO

Hello,

I have a bq2060a connected in a circuit and am communicating with it via EV2200 using 2200-60 Software. I am able to load the EEProm, calibrate voltage and current successfully, however when it comes to calibrating temperature, i run into an issue with accuracy. The range of values for the temperature offset per the datasheet is -12.8 through +12.7. The calibration occurs in Kelvin. I have a clean room that is set at 22.0C which is 295.2K. I follow the standard calibration procedures and after calibration the temperature will not budge from 375.2K. When reading the EEProm, the value is at the minimum allowance of -12.8. This is common on 45 boards so far.

Is there another software i can use with the bq2060a to calibrate the temperature? Maybe bqeasy or battery management studio? This design is old and is supporting an existing product.

Thanks

Ashley

over 5 years ago

0 Kang Kang over 5 years ago

TI__Mastermind 24870 points

Hello Ashley,

Make sure you are using the same NTC as before.

What is the error you are getting with the temperature calibration?

0 Ashley DaSilva over 5 years ago in reply to Kang Kang

Prodigy 160 points

Kang,

NTC never changed so I am confident that is not the case.

When I load the EEProm the inital offset value is set to 0.1 which will typically put me in the realm of 295 Kelvin on the EV2200-60 software. However with this batch of boards its putting me in the realm of 370 Kelvin. I attempt to calibrate and it still keeps me in the 370 Kelvin range, and the EEProm offset value goes to the min allowable range of -12.8 meaning I cant get it any lower. I have checked all of the components to ensure that there wasn't an issue with placing the wrong resistor in the temperature sensing circuit but everything checks out fine. Is there another software utility that i can use to get the temperature calibrated, other than the EV2200-60 software?

Thanks,

Ashley

0 Kang Kang over 5 years ago in reply to Ashley DaSilva

TI__Mastermind 24870 points

Hello Ashley,

That's very interesting. With the same tool on the older batch of boards, you can still get it to calibrate properly?

Can you check the voltage drop across the NTC on a good board and a bad board?

0 Ashley DaSilva over 5 years ago in reply to Kang Kang

Prodigy 160 points

The voltage drop across the NTC is 0.2V.

Is there another software i can use to communicate with the bq2060a?

0 Kang Kang over 5 years ago in reply to Ashley DaSilva

TI__Mastermind 24870 points

Hello Ashley,

Is the 0.2 V drop on a good or bad board? How do those compare?

There is no other software currently for the bq2060a. This part is unfortunately very old, for newer devices we have bqStudio support.

0 Ashley DaSilva over 5 years ago in reply to Kang Kang

Prodigy 160 points

The 0.2V is on an unknown state board. All i have are unknown state boards. What would cause a tempertaure reading to be bad? The NTC is the correct part, the dividing resistor is the correct part.

0 Kang Kang over 5 years ago in reply to Ashley DaSilva

TI__Mastermind 24870 points

Hello Ashley,

I believe it is board related.

Can you try this on an EVM?

0 Ashley DaSilva over 5 years ago in reply to Kang Kang

Prodigy 160 points

I will get an EVM on order and see if that is the case. What would be the cause of a bad temperature reading?

0 Kang Kang over 5 years ago in reply to Ashley DaSilva

TI__Mastermind 24870 points

Hello Ashley,

Depending on what voltage drop you have across TS, it may be some leakage of current. That would be my guess, but we'll have to see if you have the same behavior on the EVM.

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BQ2060A: Unable to retrieve temperature accurately.