TIDUF14 October   2022

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 BQ76952
      2. 2.3.2 LM5163
      3. 2.3.3 MSP430FR2155
      4. 2.3.4 ISO1042
      5. 2.3.5 TPS54308
      6. 2.3.6 ISO7731
      7. 2.3.7 THVD1400
      8. 2.3.8 UCC27524
      9. 2.3.9 TMP61
  8. 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 Pack Current Accuracy
      3. 3.3.3 Auxiliary Power and System Current Consumption
      4. 3.3.4 Cell Balancing
      5. 3.3.5 Protection
      6. 3.3.6 Working Modes Transition
  9. 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
  10. 5About the Author

Block Diagram

Figure 2-1 shows the system diagram.

Figure 2-1 TIDA-010216 Block Diagram

The design uses the high-accuracy battery monitor and protector bq76952 from TI to monitor each cell voltage, pack current and temperature data, and protect the battery pack from all unusual situations, including: COV, CUV, OT, overcurrent in charge and discharge and short-circuit discharge. There is a lower-power MSP430™ MCU MSP430FR2155 which communicates with the monitor, deal with all system control strategy, and upload all the requested information to the system side. This design supports isolated RS-485 communication with a three-channel digital isolator ISO7731 and a RS-485 transceiver THVD1400 for better flexibility. An isolated CAN transceiver is also present to test auxiliary power circuit performance. Five pairs of N-Channel MOSFETs are driven by a dual-channel 5-A sink and source current low-side driver (UCC27524) for fast MOSFET turn on and off. Another low side driver, the UCC27517, is used to drive pre-discharge MOSFET on and off. This design uses a 100-V input, 0.5-A, ultra-low IQ synchronous Buck DC/DC converter LM5163 to step down battery voltage to power MOSFET drivers. A fly-buck converter TPS54308 is used to generate a non-isolated 3.3 V to power MSU and an isolated 5 V to power isolated communication transceivers. A low IQ LDO TPS7A24 makes the isolated output voltage stable. A ±1%, 10-kΩ linear thermistor with positive temperature coefficient and 0603 package TMP61 is utilized to monitor the MOSFET temperature and measured by the MCU ADC.