TIDUFB6 December   2024

 

  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 MCU and CAN Interface
    3. 2.3 Highlighted Products
      1. 2.3.1 BQ78706
      2. 2.3.2 TMUX1308
      3. 2.3.3 TCAN1044-Q1
      4. 2.3.4 MSPM0G3519
      5. 2.3.5 LMR51406
      6. 2.3.6 ISO7731
      7. 2.3.7 UCC33420
      8. 2.3.8 UCC33421
      9. 2.3.9 TMP61
  9. 3Hardware, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Setup
    3. 3.3 Test Results
      1. 3.3.1 Daisy Chain
      2. 3.3.2 Cell Voltage Accuracy
      3. 3.3.3 Temperature Sensing Using TMP61
      4. 3.3.4 Temperature Sensing Timings
      5. 3.3.5 Cell Balancing and Thermal Performance
      6. 3.3.6 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

3.3.6 Current Consumption

Figure 3-7 shows the test setup for consumption. Two working modes are tested including shutdown mode and active mode. Cell0 of each BQ78706 was selected as a test point for current measurement because Cell0 is the location where the power supply cable directly connects to the GND pin of the BQ78706. In both modes, the DC source sets 40V voltage between cell0 and cell13. Additionally, an 8.22Ω current sensing resistor is added between negative terminal of DC source and GND of each BQ78706 device. An INA239 EVM board is used to measure the voltage across the current sensing resistor. The sample rate is 2ms and 60000 points of data are collected for average calculation.


TIDA-010279 Test Setup for Consumption

Figure 3-7 Test Setup for Consumption

In active mode, the BQ79600 EVM runs the cell voltage polling loop. In shutdown mode, the leakage current to the BQ78706 pin is 3.416μA, 3,65μA,3.65μA, and 4.258μA. In active mode, the working current is 10.693mA, 10.673mA, 10.544mA, and 10.717mA. The maximum AFE gap current in active mode is 134μA.

Table 3-9 shows the BMU current consumption.

Table 3-9 BMU Current Consumption
DESCRIPTION Icell0#1 Icell0#2 Icell0#3 Icell0#4
Shutdown Mode Current (μA) 3.416 3.65 3.65 4.258
Active Mode Current (mA) 10.400 10.430 10.296 10.426