TIDUF20B December   2022  – July 2025

 

  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 Configure This Design for Different Use Cases
      2. 2.2.2 Auxiliary Power Strategy
      3. 2.2.3 High-Side N-Channel MOSFET
      4. 2.2.4 Stacked AFE Communication
      5. 2.2.5 Thermistor Multiplexer
      6. 2.2.6 CAN Stacking
    3. 2.3 Highlighted Products
      1. 2.3.1  BQ76972
      2. 2.3.2  MSPM0G3519
      3. 2.3.3  UCC334xx
      4. 2.3.4  LM5168
      5. 2.3.5  ISO1640
      6. 2.3.6  ISO1042
      7. 2.3.7  ISO1410
      8. 2.3.8  TPS7A24
      9. 2.3.9  TMP61
      10. 2.3.10 TPD2E007
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Software Requirements
      1. 3.2.1 Getting Started MSPM0 Software
        1. 3.2.1.1 Download and Install Software Required for Board Test
        2. 3.2.1.2 Import the Project Into CCS
        3. 3.2.1.3 Compile the Project
        4. 3.2.1.4 Download Image and Run
      2. 3.2.2 Software Function List
        1. 3.2.2.1 Driverlib Function List
          1.        CAN_ID_Init_on_Startup
          2.        CAN_Write
          3.        CANprocessCANRxMsg
          4.        I2C_WriteReg
          5.        I2C_ReadReg
          6.        RS485_Send
          7.        RS485_Receive
        2. 3.2.2.2 Application Function List
          1.        Temp_Mux_Polling
          2.        BatteryDataUpdate_32s
          3.        BQ769x2_OTP_Programming
          4.        Check_Signal_Pattern
          5.        BMU_FET_Test
      3. 3.2.3 Software Workflow
    3. 3.3 Test Setup
    4. 3.4 Test Results
      1. 3.4.1 Cell Voltage Accuracy
      2. 3.4.2 Pack Current Accuracy
      3. 3.4.3 Auxiliary Power and System Current Consumption
      4. 3.4.4 Protection
      5. 3.4.5 Working Modes Transition
      6. 3.4.6 Thermistor Multiplexer
      7. 3.4.7 ESD Performance
      8. 3.4.8 Surge Immunity
  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
  12. 6Revision History

2.1 Block Diagram

Figure 2-1 shows the system block diagram.

TIDA-010247 TIDA-010247 Block DiagramFigure 2-1 TIDA-010247 Block Diagram

The design uses two stacked high-accuracy battery monitor and protector BQ769x2 devices from TI to monitor up to 32 series battery cells voltage, pack current, and temperature data, and protects the battery pack from all unusual situations, including: COV, CUV, OT, OCD, OCC, and SCD. This BQ769x2 family has three devices: BQ76942 to cover 3s to 10s applications, BQ769142 to cover up to 14s applications, BQ76952 to cover up to 16s applications, and the BQ76972 to achieve higher cell voltage measurement accuracy and can also cover up to 16s cells. These are pin-to-pin devices, so updating the design to match different battery cell applications with a limited number of component changes is easy. This design used the BQ76972 for tests.

There is a lower-power MSPM0 MCU MSPMP0G3519 which communicates with both BQ76972 devices, deals with all system control strategies, and uploads all the requested information to the system side. Since the top BQ76972 device references the top battery group as ground which is not the same ground with the MCU, isolation is required in the communication between the MCU and the top BQ76972 device. The ISO164x, a hot swappable, low-power, bidirectional isolated I2C interface supporting stable isolated I2C communication.

This design has both an isolated RS-485 transceiver and two isolated CAN transceivers. The isolated CAN transceiver (ISO1042) can operate from 1.8V, 2.5V, 3.3V, and 5V supplies on side 1 and a 5V supply on side 2. The ISO1042 device has an isolation withstand voltage of 5000VRMS and is available in basic and reinforced isolation with a surge test voltage of 6kVPK and 10kVPK respectively. The ISO1410 is an isolated half-duplex RS-485 transceiver that supports interfacing with 1.8V, 2.5V, 3.3V, and 5V control logic.

To power these isolated devices, this design uses a 120V input, 0.3A, ultra-low IQ synchronous buck DC/DC converter LM5168 with a low IQ as a pre-regulator. The UCC334xx(-Q1) family integrates a high-efficiency, low-emissions isolated DC/DC converter. Requiring minimum passive components to form a completely functional DC/DC power module, the UCC334x0 can deliver a maximum power of 1.5W across a 3kVRMS basic isolation barrier over a wide range of operating temperatures in a low profile and UCC334x1-Q1 has a 5kVRMS reinforced isolation with the same power delivered.

A ±1%, 10kΩ linear thermistor with positive temperature coefficient TMP61 is utilized to monitor the cell temperature and is measured by the BQ76972 device.