SLUSFB5A June   2024  – April 2025 BQ41Z50

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1. 4.1 Pin Equivalent Diagrams
  6. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Recommended Operating Conditions
    4. 5.4  Thermal Information
    5. 5.5  Supply Current
    6. 5.6  Power Supply Control
    7. 5.7  Low Dropout Regulators
    8. 5.8  Internal Oscillators
    9. 5.9  Voltage References
    10. 5.10 Current Wake Detector
    11. 5.11 VC0, VC1, VC2, VC3, VC4, PACK
    12. 5.12 Cell Balancing Support
    13. 5.13 SMBD, SMBC
    14. 5.14 PRES/SHUTDN, DISP
    15. 5.15 ALERT
    16. 5.16 LEDCNTLA, LEDCNTLB, LEDCNTLC
    17. 5.17 Coulomb Counter
    18. 5.18 Coulomb Counter Digital Filter (CC1)
    19. 5.19 Current Measurement Digital Filter (CC2)
    20. 5.20 Analog-to-Digital Converter
    21. 5.21 ADC Digital Filter
    22. 5.22 CHG, DSG High-side NFET Drivers
    23. 5.23 Precharge (PCHG) FET Drive
    24. 5.24 FUSE Drive
    25. 5.25 Internal Temperature Sensor
    26. 5.26 TS1, TS2, TS3, TS4
    27. 5.27 Flash Memory
    28. 5.28 OT, SCD, OCC, OCD1, OCD2 Protection Thresholds (SCOMP)
    29. 5.29 OT, SCD, OCC, OCD1, OCD2 Protection Timing (SCOMP)
    30. 5.30 GPIO1, GPIO2, GPIO3, GPIO4, GPIO5, GPIO6, GPIO7
    31. 5.31 Elliptical Curve Cryptography (ECC)
    32. 5.32 SMBus Interface Timing
    33. 5.33 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Primary (1st Level) Safety Features
      2. 6.3.2 Secondary (2nd Level) Safety Features
      3. 6.3.3 Charge Control Features
      4. 6.3.4 Gas Gauging
      5. 6.3.5 Lifetime Data Logging Features
      6. 6.3.6 Authentication
      7. 6.3.7 Configuration
        1. 6.3.7.1 Oscillator Function
        2. 6.3.7.2 Real Time Clock
        3. 6.3.7.3 System Present Operation
        4. 6.3.7.4 Emergency Shutdown
        5. 6.3.7.5 2-Series, 3-Series, or 4-Series Cell Configuration
        6. 6.3.7.6 Cell Balancing
        7. 6.3.7.7 LED Display
      8. 6.3.8 Battery Parameter Measurements
        1. 6.3.8.1 Charge and Discharge Counting
        2. 6.3.8.2 Voltage
        3. 6.3.8.3 Current
        4. 6.3.8.4 Temperature
        5. 6.3.8.5 Communications
          1. 6.3.8.5.1 SMBus On and Off State
          2. 6.3.8.5.2 SBS Commands
    4. 6.4 Device Functional Modes
  8. 7 Applications and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 High-Current Path
          1. 7.2.2.1.1 Protection FETs
          2. 7.2.2.1.2 Chemical Fuse
          3. 7.2.2.1.3 Lithium-Ion Cell Connections
          4. 7.2.2.1.4 Sense Resistor
          5. 7.2.2.1.5 ESD Mitigation
        2. 7.2.2.2 Gas Gauge Circuit
          1. 7.2.2.2.1 Coulomb-Counting Interface
          2. 7.2.2.2.2 Low-dropout Regulators (LDOs)
            1. 7.2.2.2.2.1 REG18
            2. 7.2.2.2.2.2 REG135
          3. 7.2.2.2.3 System Present
          4. 7.2.2.2.4 SMBus Communication
          5. 7.2.2.2.5 FUSE Circuitry
        3. 7.2.2.3 Secondary-Current Protection
          1. 7.2.2.3.1 Cell and Battery Inputs
          2. 7.2.2.3.2 External Cell Balancing
          3. 7.2.2.3.3 PACK and FET Control
          4. 7.2.2.3.4 Temperature Measurement
          5. 7.2.2.3.5 LEDs
      3. 7.2.3 Application Curves
    3. 7.3 Configuring Device Firmware
  9. 8 Power Supply Recommendations
  10. 9 Layout
    1. 9.1 Layout Guidelines
      1. 9.1.1 Protector FET Bypass and Pack Terminal Bypass Capacitors
      2. 9.1.2 ESD Spark Gap
    2. 9.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Third-Party Products Disclaimer
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
7.2.2.2.3 System Present

The system present signal is used to inform the gas gauge whether the pack is installed into or removed from the system. In the host system, this pin is grounded. The BQ41Z50PRES pin is occasionally sampled to test for system present for applications with a removable battery pack. To save power, the internal weak pull-up on the PRES pin is used by the gas gauge during a brief sampling pulse once per 250ms. A resistor can be used to pull the signal low and the total resistance must be no greater than 340kΩ to ensure the test pulse is lower than the VIL limit. The pullup voltage is sourced from REG18.

BQ41Z50 System Present Pull-Down Resistor Figure 7-8 System Present Pull-Down Resistor

Because the system present signal is part of the pack connector interface to the outside world, it must be protected from external electrostatic discharge events. The PRES pin has integrated ESD protection circuits. However, an ESD TVS diode (U3), such as TPD1E10B06 with a 30kV ESD contact rating, can be used to provide supplemental protection against such events.

BQ41Z50 System Present ESD and Short Protection Figure 7-9 System Present ESD and Short Protection