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
7.2.2.1.1 Protection FETs

Select the N-channel charge and discharge FETs for a given application. Most portable battery applications are a good match for the CSD17308Q3. For more information, please see CSD17308Q3 30-V N-Channel NexFET™ Power MOSFETs. The TI CSD17308Q3 is a 47A, 30-V device with RDS(ON) of 8.2mΩ when the gate drive voltage is 8V.

If a precharge FET is used, R2 is calculated to limit the precharge current to the desired rate. Be sure to account for the power dissipation of the series resistor. The precharge current is limited to (VCHARGER – VBAT)/R2 and maximum power dissipation is (VCHARGER – VBAT)2/R2.

The gates of all protection FETs are pulled to the source with a high-value resistor between the gate and source to ensure they are turned off if the gate drive is open.

Capacitors C1 and C2 help protect the FETs during an ESD event. Using two devices ensures normal operation if one becomes shorted. To have good ESD protection, the copper trace inductance of the capacitor leads must be designed to be as short and wide as possible. Ensure that the voltage rating of both C1 and C2 are adequate to hold off the applied voltage if one of the capacitors becomes shorted.

BQ41Z50 BQ41Z50 Protection FETs Figure 7-2 BQ41Z50 Protection FETs