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

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
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 NUMBER PACKAGE BODY SIZE (NOM)
bq76925 TSSOP (20) 4.00 mm × 4.00 mm
bq76925 VQFN (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