SLVT251 July   2026

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 High-Voltage Stackable Architecture
      2. 2.2.2 Electrochemical Impedance Spectroscopy (EIS) Subsystem
      3. 2.2.3 EIS Synchronization Requirement
      4. 2.2.4 PWM Input as Crystal of the First BQ79826Z-Q1
      5. 2.2.5 Temperature Sensing and Multiplexer Network
      6. 2.2.6 Cell Balancing Circuit and Operation
      7. 2.2.7 MCU and System Control Architecture
      8. 2.2.8 Protection and On-Board Diagnostics
    3. 2.3 Highlighted Products
      1. 2.3.1 BQ79826Z-Q1
      2. 2.3.2 TMUX1308
      3. 2.3.3 TMP61
      4. 2.3.4 SN74LXC1T14
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Software
    3. 3.3 Test Setup
    4. 3.4 Pack Test Results
      1. 3.4.1 Cell Voltage Reliability Test
      2. 3.4.2 EIS Measurement Repeatability
      3. 3.4.3 Pack EIS Measurement Nyquist Plot
      4. 3.4.4 Current Consumption per BQ79826Z-Q1
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
      3. 4.1.3 PCB Layout Recommendations
    2. 4.2 Tools and Software
      1. 4.2.1 Tools
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5.     Trademarks
  11. 5About the Author

1.1 Key System Specifications

General System Features

  • Supports up to 1500V stackable ESS, 52S per BMU board, expandable to 104S battery pack
  • Cell voltage accuracy: ±1.7mV across –40°C to 125°C without factory calibration
  • Full cell-to-temperature coverage via TMUX1308 analog multiplexer expansion
  • Ultra-low power modes: 5µA shutdown, 20µA sleep, 3mA typical operating current
  • Robust isolated daisy-chain with ring network support for multi-board stacking
  • Full protection: OVP, UVP, OTP, UTP, open-wire, communication fault diagnosis

EIS Exclusive Features

  • EIS frequency range: 0.01Hz to 3.5kHz for full battery characteristic analysis
  • Reuse active balancing circuit as EIS excitation source, max 5A excitation current
  • Impedance precision: magnitude deviation <2%, phase deviation <1° full temperature range
  • Time-sharing multiplexing of EIS scanning and APB balancing without mutual interference
  • Enables thermal runaway early detection, high-precision SoC/SoH, lithium plating monitoring