SLUSEN5A August   2023  – August 2026 BQ25756

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  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 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 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  Device Power-On-Reset
      2. 6.3.2  Device Power-Up From Battery Without Input Source
      3. 6.3.3  Device Power Up from Input Source
        1. 6.3.3.1 VAC Operating Window Programming (ACUV and ACOV)
        2. 6.3.3.2 REGN Regulator (REGN LDO)
        3. 6.3.3.3 Compensation-Free Buck-Boost Converter Operation
        4. 6.3.3.4 Light-Load Operation
        5. 6.3.3.5 Switching Frequency and Synchronization (FSW_SYNC)
        6. 6.3.3.6 Device HIZ Mode
      4. 6.3.4  Battery Charging Management
        1. 6.3.4.1 Autonomous Charging Cycle
          1. 6.3.4.1.1 Charge Current Programming (ICHG pin and ICHG_REG)
        2. 6.3.4.2 Li-Ion Battery Charging Profile
        3. 6.3.4.3 LiFePO4 Battery Charging Profile
        4. 6.3.4.4 Charging Termination for Li-ion and LiFePO4
        5. 6.3.4.5 Charging Safety Timer
        6. 6.3.4.6 Thermistor Qualification
          1. 6.3.4.6.1 JEITA Guideline Compliance in Charge Mode
          2. 6.3.4.6.2 Cold/Hot Temperature Window in Reverse Mode
      5. 6.3.5  Power Management
        1. 6.3.5.1 Dynamic Power Management: Input Voltage and Input Current Regulation
          1. 6.3.5.1.1 Input Current Regulation
            1. 6.3.5.1.1.1 ILIM_HIZ Pin
          2. 6.3.5.1.2 Input Voltage Regulation
            1. 6.3.5.1.2.1 Max Power Point Tracking (MPPT) for Solar PV Panel
      6. 6.3.6  Reverse Mode Power Direction
      7. 6.3.7  Integrated 16-Bit ADC for Monitoring
      8. 6.3.8  Status Outputs (PG, STAT1, STAT2, and INT)
        1. 6.3.8.1 Power Good Indicator (PG)
        2. 6.3.8.2 Charging Status Indicator (STAT1, STAT2 Pins)
        3. 6.3.8.3 Interrupt to Host (INT)
      9. 6.3.9  Protections
        1. 6.3.9.1 Voltage and Current Monitoring
          1. 6.3.9.1.1 VAC Over-voltage Protection (VAC_OVP)
          2. 6.3.9.1.2 VAC Under-voltage Protection (VAC_UVP)
          3. 6.3.9.1.3 Battery Over-voltage Protection (BAT_OVP)
          4. 6.3.9.1.4 Battery Over-current Protection (BAT_OCP)
          5. 6.3.9.1.5 Reverse Mode Over-voltage Protection (REV_OVP)
          6. 6.3.9.1.6 Reverse Mode Under-voltage Protection (REV_UVP)
          7. 6.3.9.1.7 DRV_SUP Under-voltage and Over-voltage Protection (DRV_OKZ)
          8. 6.3.9.1.8 REGN Under-voltage Protection (REGN_OKZ)
        2. 6.3.9.2 Thermal Shutdown (TSHUT)
      10. 6.3.10 Serial Interface
        1. 6.3.10.1 Data Validity
        2. 6.3.10.2 START and STOP Conditions
        3. 6.3.10.3 Byte Format
        4. 6.3.10.4 Acknowledge (ACK) and Not Acknowledge (NACK)
        5. 6.3.10.5 Target Address and Data Direction Bit
        6. 6.3.10.6 Single Write and Read
        7. 6.3.10.7 Multi-Write and Multi-Read
    4. 6.4 Device Functional Modes
      1. 6.4.1 Host Mode and Default Mode
      2. 6.4.2 Register Bit Reset
    5. 6.5 BQ25756 Registers
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Typical Application
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 ACUV / ACOV Input Voltage Operating Window Programming
          2. 7.2.1.2.2 Charge Voltage Selection
          3. 7.2.1.2.3 Switching Frequency Selection
          4. 7.2.1.2.4 Inductor Selection
          5. 7.2.1.2.5 Input (VAC) Capacitor
          6. 7.2.1.2.6 Output (VBAT) Capacitor
          7. 7.2.1.2.7 Sense Resistor (RAC_SNS and R BAT_SNS ) and Current Programming
          8. 7.2.1.2.8 Power MOSFETs Selection
          9. 7.2.1.2.9 Converter Fast Transient Response
        3. 7.2.1.3 Application Curves
      2. 7.2.2 Typical Application (USB-PD EPR Configuration)
        1. 7.2.2.1 Design Requirements
  9. 8 Power Supply Recommendations
  10. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

6.3.6 Reverse Mode Power Direction

The device supports buck-boost reverse power direction with CC/CV profile to deliver power from the battery to the input when the adapter is not present. The reverse mode output voltage regulation is set in VAC_REV register bits. The reverse mode also offers output current regulation via the RAC_SNS resistor. This parameter is controlled by the IAC_REV register bits. The reverse mode operation can be enabled if the following conditions are valid:

  1. SRN above 3.8V.
  2. DRV_SUP voltage within valid operating window (VDRV_UVP < VDRV < VDRV_OVP.
  3. Reverse mode operation is enabled (EN_REV = 1)
  4. Voltage at TS (thermistor) pin is within range configured by Reverse Temperature Monitor as configured by BHOT and BCOLD register bits

While the reverse mode is active, the device sets the REVERSE_STAT bit to 1. Host can disable the reverse operation at any time by setting EN_REV bit to 0.

The charger also monitors and regulates the battery discharging current in reverse mode. When the battery discharge current rises above the IBAT_REV register setting, the charger reduces the reverse mode power flow to limit the discharge current.

A minimum of 3.8V is needed to start the reverse mode successfully. However, once already in reverse mode, the VBAT side can be reduced up to 2.5V before the reverse mode turns off.