SLUSBK2I October   2013  – March 2022 BQ76920 , BQ76930 , BQ76940

PRODMIX  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1. 6.1 Versions
    2. 6.2 BQ76920 Pin Diagram
    3. 6.3 BQ76930 Pin Diagram
    4. 6.4 BQ76940 Pin Diagram
  7. 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
    6. 7.6 Timing Requirements
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Subsystems
        1. 8.3.1.1 Measurement Subsystem Overview
          1. 8.3.1.1.1 Data Transfer to the Host Controller
          2. 8.3.1.1.2 14-Bit ADC
            1. 8.3.1.1.2.1 Optional Real-Time Calibration Using the Host Microcontroller
          3. 8.3.1.1.3 16-Bit CC
          4. 8.3.1.1.4 External Thermistor
          5. 8.3.1.1.5 Die Temperature Monitor
          6. 8.3.1.1.6 16-Bit Pack Voltage
          7. 8.3.1.1.7 System Scheduler
        2. 8.3.1.2 Protection Subsystem
          1. 8.3.1.2.1 Integrated Hardware Protections
          2. 8.3.1.2.2 Reduced Test Time
        3. 8.3.1.3 Control Subsystem
          1. 8.3.1.3.1 FET Driving (CHG AND DSG)
            1. 8.3.1.3.1.1 High-Side FET Driving
          2. 8.3.1.3.2 Load Detection
          3. 8.3.1.3.3 Cell Balancing
          4. 8.3.1.3.4 Alert
          5. 8.3.1.3.5 Output LDO
        4. 8.3.1.4 Communications Subsystem
    4. 8.4 Device Functional Modes
      1. 8.4.1 NORMAL Mode
      2. 8.4.2 SHIP Mode
    5. 8.5 Register Maps
      1. 8.5.1 Register Details
      2. 8.5.2 Read-Only Registers
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Device Timing
      2. 9.1.2 Random Cell Connection
      3. 9.1.3 Power Pin Diodes
      4. 9.1.4 Alert Pin
      5. 9.1.5 Sense Inputs
      6. 9.1.6 TSn Pins
      7. 9.1.7 Unused Pins
      8. 9.1.8 Configuring Alternative Cell Counts
    2. 9.2 Typical Applications
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Step-by-Step 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 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
    3. 12.3 Related Links
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Trademarks
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
8.3.1.1.4 External Thermistor

One (BQ76920), two (BQ76930), or three (BQ76940) 10-kΩ NTC 103AT thermistors may be measured by the device. These are measured by applying a factory-trimmed internal 10-k pull-up resistance to an internal regulator value of nominally 3.3 V, the result of which can be read out from the TSx (TS1, TS2, TS3) registers.

To select thermistor measurement mode, set [TEMP_SEL] = 1.

Thermistor TS1 is connected between TS1 and VSS; TS2 is connected between TS2 and VC5x (BQ76930 and BQ76940 only); and TS3 is connected between TS3 and VC10x (BQ76940 only). These thermistors may be placed in various areas in the battery pack to measure such things as localized cell temperature, FET heating, and so forth.

The thermistor impedance may be calculated using the 14-bit ADC reading in the TS1, TS2, and TS3 registers and 10-k internal pull-up resistance as follows:

The following equations show how to use the 14-bit ADC readings in TS1, TS2, and TS3 to determine the resistance of the external 103AT thermistor:

Equation 4. VTSX = (ADC in Decimal) x 382 µV/LSB
Equation 5. RTS = (10,000 × VTSX) ÷ (3.3 – VTSX)

To convert the thermistor resistance into temperature, please refer to the thermistor component manufacturer’s data sheet.