BQ76952: BQ76952 Temperature Calibration with Two Different NTCs

Tool/software:

Hi TI team,

We are currently using the BQ76952 AFE IC in our project. For temperature monitoring, we use two different NTC thermistors with different temperature coefficients:

1. NTC1: Measures cell temperature

2. NTC2: Measures MOSFET temperature

NTC.pptx

We have used the bq769x2 Thermistor Coeff Calculator to calculate the coefficients:

          NTC1:

          NTC2:

We input the calculated coefficients into the Data Memory of bqStudio under:

• 18k Temperature Model

• Custom Temperature Model

  

And we've configured the GG FIRE settings accordingly.

However, the measured temperatures are inaccurate — sometimes slightly off, sometimes significantly incorrect.

We have a few questions regarding this:

1. In the 18k Temperature Model, how do we determine the correct Adc0 value?

2. In the Custom Temperature Model, how do we determine the correct Rc0 and Adc0 values?

3. Our MOSFET protection threshold can go up to 135°C. How should we define the coefficients in the Custom Temperature Model to ensure accurate readings above 115°C?

4. Is our general approach to using 18k Temperature Model and Custom Temperature Model in bqStudio Data Memory for two different NTCs correct? Or is there a recommended method to handle different NTC types more accurately?

We’ve attached the NTC resistance-temperature tables for reference.

Looking forward to your suggestions, thank you!