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

3.3.5 Current Consumption

Figure 3-14 shows the test point of the current consumption in BMU test setup. Two working modes are tested including shutdown mode and active mode. Cell16 and cell32 were selected as test points for current because they are the locations where the power supply cable directly connects to the BAT pin of the BQ79616. In both modes, the battery simulator sets 3.2-V cell voltage.

GUID-20230925-SS0I-K0GR-788C-D8592SWVVNS4-low.svgFigure 3-8 Test Point of Current Consumption in BMU Test Setup

In active mode, the BCU runs the test loop in Figure 2-2 in 100-ms duty cycle. In shutdown mode, the leakage current to the BQ79616 BAT pin is 14.6 μA and 15.5 μA. In active mode, the working current is 18.39 mA and 18.22 mA. Table 3-11 shows the BMU current consumption from the battery.

Table 3-11 BMU Current Consumption From Battery
DESCRIPTIONIcell16Icell32
Shutdown ModeCurrent (μA)14.6015.50
Active ModeCurrent (mA)18.3918.22

The test also uses an isolated UART interface to communicate with the BMU instead of the BCU. A USB2ANY is used to enable the optocoupler. When the enable signal is sent to the optocoupler, the BMU transfers from shutdown mode to standby mode. At this time, CVDD of BQ79616 is switched to the ISO7742 and a leakage current near 5.393 mA flows to ISO7742. After the UART communication starts, the BMU enters the active mode and the leakage current to ISO7742 rises to 7.042 mA. Table 3-12 shows BMU current consumption to the isolated UART interface.

Table 3-12 BMU Current Consumption to Isolated UART Interface
DESCRIPTIONI_CVDD
Shutdown ModeCurrent (μA)0.001
Standby ModeCurrent (mA)5.393
Active ModeCurrent (mA)7.042