SLUSAM9D July 2011  – October 2016

PRODUCTION DATA. 

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Description (Continued)
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics: Supply Current
    6. 7.6 Internal Power Control (Startup and Shutdown)
    7. 7.7 3.3-V Voltage Regulator
    8. 7.8 Voltage Reference
    9. 7.9 Cell Voltage Amplifier
    10. 7.10Current Sense Amplifier
    11. 7.11Overcurrent Comparator
    12. 7.12Internal Temperature Measurement
    13. 7.13Cell Balancing and Open Cell Detection
    14. 7.14I2C Compatible Interface
    15. 7.15Typical Characteristics
  8. Detailed Description
    1. 8.1Overview
    2. 8.2Functional Block Diagram
    3. 8.3Feature Description
      1. 8.3.1Internal LDO Voltage Regulator
      2. 8.3.2ADC Interface
        1. 8.3.2.1Reference Voltage
          1. 8.3.2.1.1Host ADC Calibration
        2. 8.3.2.2Cell Voltage Monitoring
          1. 8.3.2.2.1Cell Amplifier Headroom Under Extreme Cell Imbalance
          2. 8.3.2.2.2Cell Amplifier Headroom Under BAT Voltage Drop
        3. 8.3.2.3Current Monitoring
        4. 8.3.2.4Overcurrent Monitoring
        5. 8.3.2.5Temperature Monitoring
          1. 8.3.2.5.1Internal Temperature Monitoring
      3. 8.3.3Cell Balancing and Open Cell Detection
    4. 8.4Device Functional Modes
      1. 8.4.1Power Modes
        1. 8.4.1.1POWER ON RESET (POR)
        2. 8.4.1.2STANDBY
        3. 8.4.1.3SLEEP
    5. 8.5Programming
      1. 8.5.1Host Interface
        1. 8.5.1.1I2C Addressing
        2. 8.5.1.2Bus Write Command to bq76925
        3. 8.5.1.3Bus Read Command from bq76925 Device
    6. 8.6Register Maps
      1. 8.6.1Register Descriptions
  9. Application and Implementation
    1. 9.1Application Information
      1. 9.1.1Recommended System Implementation
        1. 9.1.1.1Voltage, Current, and Temperature Outputs
        2. 9.1.1.2Power Management
        3. 9.1.1.3Low Dropout (LDO) Regulator
        4. 9.1.1.4Input Filters
        5. 9.1.1.5Output Filters
      2. 9.1.2Cell Balancing
    2. 9.2Typical Application
      1. 9.2.1Design Requirements
      2. 9.2.2Detailed Design Procedure
      3. 9.2.3Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1Layout Guidelines
    2. 11.2Layout Example
  12. 12Device and Documentation Support
    1. 12.1Documentation Support
      1. 12.1.1Related Documentation
    2. 12.2Receiving Notification of Documentation Updates
    3. 12.3Community Resources
    4. 12.4Trademarks
    5. 12.5Electrostatic Discharge Caution
    6. 12.6Glossary
  13. 13Mechanical, Packaging, and Orderable Information

1 Features

  • Analog Interface for Host Cell Measurement
    • Cell Input MUX, Level Shifter, and Scaler
    • 1.5-/ 3.0-V Low-Drift, Calibrated Reference Allows Accurate Analog-to-Digital Conversions
  • Analog Interface for Host Current Measurement
    • Variable Gain Current Sense Amplifier Capable of Operation with 1-mΩ Sense Resistor
  • Switchable Thermistor Bias Output for Host Temperature Measurements
  • Overcurrent Comparator With Dynamically Adjustable Threshold
    • Alerts Host to Potential Overcurrent Faults
    • Wakes up Host on Load Connect
  • Integrated Cell Balancing FETs
    • Individual Host Control
    • 50 mA per Cell Balancing Current
  • Supports Cell Sense-Line Open Wire Detection
  • Integrated 3.3-V Regulator for Powering Micro-Controller or LEDs
  • I2C Interface for Host Communications
    • Optional Packet CRC for Robust Operation
  • Supply Voltage Range From 4.2 to 26.4 V
  • Low Power Consumption
    • 40 µA Typical in Normal Mode
    • 1.5 µA Maximum in Sleep Mode
  • 20-Pin TSSOP or 24-Pin VQFN Package

2 Applications

  • Primary Protection in Li-Ion Battery Packs
    • Cordless Power Tools
    • Light Electric Vehicles (E-Bike, Scooter, and so forth)
    • UPS Systems
    • Medical Equipment
    • Portable Test Equipment

3 Description

The bq76925 host-controlled analog front end (AFE) is part of a complete pack monitoring, balancing, and protection system for 3-, 4-, 5-, or 6-series cell Li-Ion and Li-Polymer batteries. The bq76925 device allows a Host controller to monitor individual cell voltages, pack current and temperature easily. The Host may use this information to determine unsafe or faulty operating conditions such as overvoltage, under- voltage, overtemperature, overcurrent, cell imbalance, state of charge, and state of health conditions.

Cell input voltages are level-shifted, multiplexed, scaled, and output for measurement by a Host ADC. A dedicated pin provides a low-drift calibrated reference voltage to enable accurate measurements.

Device Information(1)

PART NUMBERPACKAGEBODY SIZE (NOM)
bq76925TSSOP (20)4.00 mm × 4.00 mm
bq76925VQFN (24)6.50 mm × 4.40 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.

Simplified Schematic

bq76925 simplified_sch_lusam9.gif