TIDUF46 October   2023

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Multiplexer Network and Switch Strategy
      2. 2.2.2 Cell Balancing
      3. 2.2.3 Stacked AFE Communication
      4. 2.2.4 Isolated UART Interface to MCU
    3. 2.3 Highlighted Products
      1. 2.3.1 BQ79616
      2. 2.3.2 TMUX1308
      3. 2.3.3 TMUX1574
      4. 2.3.4 TMUX1102
      5. 2.3.5 TPS22810
      6. 2.3.6 ISO7742
      7. 2.3.7 TSD05C
      8. 2.3.8 ESD441
      9. 2.3.9 ESD2CAN24-Q1
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Setup
    3. 3.3 Test Results
      1. 3.3.1 Cell Voltage Accuracy
      2. 3.3.2 Temperature Sensing Accuracy
      3. 3.3.3 Cell Voltage and Temperature Sensing Timings
      4. 3.3.4 Cell Balancing and Thermal Performance
      5. 3.3.5 Current Consumption
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Tools and Software
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks
  11. 5About the Author

3.3.2 Temperature Sensing Accuracy

A thermistor card board is used to verify the temperature sensing accuracy of the BMU in a climate chamber. A thermocouple with an accuracy of ±1°C is connected to NTC thermistor 6. The BMU NTC thermistor resistance RNTC_0 can be calculated with VNTC from the GPIO1 and TSREF voltages. The test uses two methods to calculate the temperature. A simple Steinhart-Hart equation (Equation 1) accurate for a small range is used to calculate the BMU NTC thermistor temperature.

Equation 1. E q u a t i o n   t e m p e r a t u r e = B 25 85 × 298.15 298.15 × log ⁡ R N T C _ 0 R N T C + B 25 85

For better accuracy, a Thermistor R/T Table look-up and linear fit method is used to calculate the temperature.

Figure 3-14 shows temperature sensing accuracy. The maximum temperature error is 1°C in –35°C to 85°C.

GUID-20230925-SS0I-CBCT-BH2G-ZDC83MDHCT4Z-low.svg Figure 3-3 Temperature Sensing Accuracy

Figure 3-4 shows thermistor voltage accuracy. The maximum voltage error is 2 mV in –35°C to 85°C.

GUID-20230925-SS0I-LTCL-HDSR-9RCWLL2VPPWK-low.svg Figure 3-4 Thermistor Voltage Accuracy