SLUSFF4 November   2023 BQ25756E

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Description (continued)
  6. 5 Device Comparison
  7. 6 Pin Configuration and Functions
  8. 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 (BQ25756E)
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Device Power-On-Reset
      2. 8.3.2  Device Power-Up From Battery Without Input Source
      3. 8.3.3  Device Power Up from Input Source
        1. 8.3.3.1 VAC Operating Window Programming (ACUV and ACOV)
        2. 8.3.3.2 REGN Regulator (REGN LDO)
        3. 8.3.3.3 Compensation-Free Buck-Boost Converter Operation
          1. 8.3.3.3.1 Light-Load Operation
        4. 8.3.3.4 Switching Frequency and Synchronization (FSW_SYNC)
        5. 8.3.3.5 Device HIZ Mode
      4. 8.3.4  Battery Charging Management
        1. 8.3.4.1 Autonomous Charging Cycle
          1. 8.3.4.1.1 Charge Current Programming (ICHG pin and ICHG_REG)
        2. 8.3.4.2 Li-Ion Battery Charging Profile
        3. 8.3.4.3 LiFePO4 Battery Charging Profile
        4. 8.3.4.4 Charging Termination for Li-ion and LiFePO4
        5. 8.3.4.5 Charging Safety Timer
        6. 8.3.4.6 CV Timer
        7. 8.3.4.7 Thermistor Qualification
          1. 8.3.4.7.1 JEITA Guideline Compliance in Charge Mode
          2. 8.3.4.7.2 Cold/Hot Temperature Window in Reverse Mode
      5. 8.3.5  Power Management
        1. 8.3.5.1 Dynamic Power Management: Input Voltage and Input Current Regulation
          1. 8.3.5.1.1 Input Current Regulation
            1. 8.3.5.1.1.1 ILIM_HIZ Pin
          2. 8.3.5.1.2 Input Voltage Regulation
            1. 8.3.5.1.2.1 Max Power Point Tracking (MPPT) for Solar PV Panel
      6. 8.3.6  Reverse Mode Power Direction
      7. 8.3.7  Integrated 16-Bit ADC for Monitoring
      8. 8.3.8  Status Outputs (PG, STAT1, STAT2, and INT)
        1. 8.3.8.1 Power Good Indicator (PG)
        2. 8.3.8.2 Charging Status Indicator (STAT1, STAT2 Pins)
        3. 8.3.8.3 Interrupt to Host (INT)
      9. 8.3.9  Protections
        1. 8.3.9.1 Voltage and Current Monitoring
          1. 8.3.9.1.1 VAC Over-voltage Protection (VAC_OVP)
          2. 8.3.9.1.2 VAC Under-voltage Protection (VAC_UVP)
          3. 8.3.9.1.3 Battery Over-voltage Protection (BAT_OVP)
          4. 8.3.9.1.4 Battery Over-current Protection (BAT_OCP)
          5. 8.3.9.1.5 Reverse Mode Over-voltage Protection (REV_OVP)
          6. 8.3.9.1.6 Reverse Mode Under-voltage Protection (REV_UVP)
          7. 8.3.9.1.7 DRV_SUP Under-voltage and Over-voltage Protection (DRV_OKZ)
          8. 8.3.9.1.8 REGN Under-voltage Protection (REGN_OKZ)
        2. 8.3.9.2 Thermal Shutdown (TSHUT)
      10. 8.3.10 Serial Interface
        1. 8.3.10.1 Data Validity
        2. 8.3.10.2 START and STOP Conditions
        3. 8.3.10.3 Byte Format
        4. 8.3.10.4 Acknowledge (ACK) and Not Acknowledge (NACK)
        5. 8.3.10.5 Target Address and Data Direction Bit
        6. 8.3.10.6 Single Write and Read
        7. 8.3.10.7 Multi-Write and Multi-Read
    4. 8.4 Device Functional Modes
      1. 8.4.1 Host Mode and Default Mode
      2. 8.4.2 Register Bit Reset
    5. 8.5 BQ25756E Registers
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Typical Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 ACUV / ACOV Input Voltage Operating Window Programming
          2. 9.2.1.2.2 Charge Voltage Selection
          3. 9.2.1.2.3 Switching Frequency Selection
          4. 9.2.1.2.4 Inductor Selection
          5. 9.2.1.2.5 Input (VAC) Capacitor
          6. 9.2.1.2.6 Output (VBAT) Capacitor
          7. 9.2.1.2.7 Sense Resistor (RAC_SNS and RBAT_SNS) and Current Programming
          8. 9.2.1.2.8 Power MOSFETs Selection
          9. 9.2.1.2.9 Converter Fast Transient Response
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Typical Application (USB-PD EPR Configuration)
        1. 9.2.2.1 Design Requirements
  11. 10Power Supply Recommendations
  12. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  13. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  14. 13Revision History
  15. 14Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.4.3 LiFePO4 Battery Charging Profile

The device charges the battery in five phases: trickle charge, pre-charge, constant current, constant voltage, and top-off trickle charging (optional). At the beginning of a charging cycle, the device checks the battery voltage and regulates current/voltage accordingly.

Table 8-5 Recommended LiFePO4 Charge Settings
PARAMETERI2C REGISTER BITSVALUEEQUIVALENT PER 3.6-V CHARGE (V)
Battery Low VoltageVBAT_LOWV0x1 = 55% x VFB_REG1.98 V
Recharge VoltageVRECHG0x0 = 93% x VFB_REG3.35 V

If the charger device is in DPM regulation during charging, the actual charging current will be less than the programmed value. In this case, termination is temporarily disabled and the charging safety timer is counted at half the clock rate, as explained in Charging Safety Timer. The typical charging cycle for LiFePO4 follows the same profile as Typical Li-Ion Battery Charging Profile.