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

1 System Description

Energy storage systems (ESS) play an important role in renewable energy applications. Depending on the system voltage, capacity, and usage, ESS can be divided into three different categories: residential ESS, commercial and industrial ESS, and grid ESS. Commercial and industrial, and grid ESS contain several racks that each contain packs in a stack. Residential ESS only contains packs.

Battery pack which consists of battery cells in a series and parallel connection manner is a basic module comprising the ESS. Because of the weight limit and longer endurance needs, the battery cell chemistry is shifting from Lead-acid to Li-ion, Li-polymer, or Li-ion phosphate (LiFePO4) types and the pack voltage is shifting from 24V or 48V to 96V or 192V, or even higher. These battery chemistries are good in both volumetric and gravimetric energy density. While these battery chemistries provide high energy density and thereby lower volume and weight as an advantage, these battery products are associated with safety concerns and have a need for more accurate and complicated monitoring and protections. Those concerns are cell undervoltage (CUV) and cell overvoltage (COV), overtemperature (OT), both overcurrent in charge (OCC) and discharge (OCD), and short-circuit discharge (SCD), all of which contribute to accelerating cell degradation and can lead to thermal runaway and explosion. Therefore, the pack current, cell temperature, and each cell voltage must be monitored in a timely manner in case of unusual situations. The battery pack must be protected against all these situations. Good measurement accuracy is always required, especially the cell voltage, pack current, and cell temperature. Precision is necessary for accurate protections and battery pack state of charge (SoC) calculations. This is especially true for LiFePO4 battery pack applications because of the flat voltage. Another important feature for battery-powered applications is the current consumption, especially when in ship mode or standby mode. Lower current consumption saves more energy and gives longer storage time without over-discharging the battery.

For the communication interface between BMU, controller area network (CAN) is traditionally and widely used for robustness of communication. A CAN structure controller needs a microcontroller unit (MCU), a digital isolator, and an isolated power module to operate the CAN communication function. Another approach is daisy chain which requires less components than CAN interface for proper work, but this approach needs battery management IC support daisy chain communication, meaning this is a private protocol defined by IC vendors.

This design, with two stacked BQ769x2 battery monitors to cover up to 32s battery cells, focuses on 48V and residential battery pack applications and integrates the CAN interface stacking function for compatibility with high-voltage applications, such as commercial and industrial ESS. The design contains full set protection to protect the battery pack against all unusual situations including: cell overvoltage, cell undervoltage, overtemperature, overcurrent in charge and discharge, and short-circuit discharge. With high-side MOSFET control, normal communication outside is allowed even during faults and MOSFETs in the off status. This design has carefully formed two kinds of auxiliary power architecture, one is for residential ESS and another for commercial and industrial ESS. This design achieves an ultra-low ship mode (10μA) and standby mode (300μA) current consumption with a limited number of components and simple control strategy. This design also contains a thermistor multiplexer circuit to support 32s cell temperature measurement.