SLVSDU0B September   2017  – September 2019 BQ25910

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Schematic
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Device Power-On-Reset (POR)
      2. 7.3.2  Device Power Up from Battery without Input Source
      3. 7.3.3  Device Power Up from Input Source
      4. 7.3.4  Power Up REGN LDO
      5. 7.3.5  Poor Source Qualification
      6. 7.3.6  Converter Power-Up
      7. 7.3.7  Three-Level Buck Converter Theory of Operation
      8. 7.3.8  Host Mode and Default Mode
        1. 7.3.8.1 Host Mode and Default Mode in BQ25910
      9. 7.3.9  Battery Charging Management
        1. 7.3.9.1 Autonomous Charging Cycle
      10. 7.3.10 Master Charger and Parallel Charger Interactions
      11. 7.3.11 Battery Charging Profile
        1. 7.3.11.1 Charging Termination
        2. 7.3.11.2 Differential Battery Voltage Remote Sensing
        3. 7.3.11.3 Charging Safety Timer
    4. 7.4 Device Functional Modes
      1. 7.4.1 Lossless Current Sensing
      2. 7.4.2 Dynamic Power Management
      3. 7.4.3 Interrupt to Host (INT)
      4. 7.4.4 Protections
        1. 7.4.4.1 Voltage and Current Monitoring
          1. 7.4.4.1.1 Input Over-Voltage (VVBUS_OV)
          2. 7.4.4.1.2 Input Under-Voltage (VPOORSRC)
          3. 7.4.4.1.3 Flying Capacitor Over- or Under-Voltage Protection (VCFLY_OVP and VCFLY_UVP)
          4. 7.4.4.1.4 Over Current Protection
        2. 7.4.4.2 Thermal Regulation and Thermal Shutdown
        3. 7.4.4.3 Battery Protection
          1. 7.4.4.3.1 Battery Over-Voltage Protection (BATOVP)
    5. 7.5 Programming
      1. 7.5.1 Serial Interface
      2. 7.5.2 Data Validity
      3. 7.5.3 START and STOP Conditions
      4. 7.5.4 Byte Format
      5. 7.5.5 Acknowledge (ACK) and Not Acknowledge (NACK)
      6. 7.5.6 Slave Address and Data Direction Bit
      7. 7.5.7 Single Read and Write
      8. 7.5.8 Multi-Read and Multi-Write
    6. 7.6 Register Maps
      1. 7.6.1 I2C Registers
        1. 7.6.1.1  Battery Voltage Regulation Limit Register (Address = 0h) [reset = AAh]
          1. Table 5. REG00 Register Field Descriptions
        2. 7.6.1.2  Charger Current Limit Register (Address = 1h) [reset = 46h]
          1. Table 6. REG01 Register Field Descriptions
        3. 7.6.1.3  Input Voltage Limit Register (Address = 2h) [reset = 04h]
          1. Table 7. REG02 Register Field Descriptions
        4. 7.6.1.4  Input Current Limit Register (Address = 3h) [reset = 13h]
          1. Table 8. REG03 Register Field Descriptions
        5. 7.6.1.5  Reserved Register (Address = 4h) [reset = 03h]
          1. Table 9. REG04 Register Field Descriptions
        6. 7.6.1.6  Charger Control 1 Register (Address = 5h) [reset = 9Dh]
          1. Table 10. REG05 Register Field Descriptions
        7. 7.6.1.7  Charger Control 2 Register (Address = 6h) [reset = 33h]
          1. Table 11. REG06 Register Field Descriptions
        8. 7.6.1.8  INT Status Register (Address = 7h) [reset = X]
          1. Table 12. REG07 Register Field Descriptions
        9. 7.6.1.9  FAULT Status Register (Address = 8h) [reset = X]
          1. Table 13. REG08 Register Field Descriptions
        10. 7.6.1.10 INT Flag Status Register (Address = 9h) [reset = 00h]
          1. Table 14. REG09 Register Field Descriptions
        11. 7.6.1.11 FAULT Flag Register (Address = Ah) [reset = 00h]
          1. Table 15. REG0A Register Field Descriptions
        12. 7.6.1.12 INT Mask Register (Address = Bh) [reset = 00h]
          1. Table 16. REG0h Register Field Descriptions
        13. 7.6.1.13 FAULT Mask Register (Address = Ch) [reset = 00h]
          1. Table 17. REG0C Register Field Descriptions
        14. 7.6.1.14 Part Information Register (Address = Dh) [reset = 0Ah]
          1. Table 18. REG0D Register Field Descriptions
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 External Passive Recommendation
        2. 8.2.2.2 Inductor Selection
        3. 8.2.2.3 Input Capacitor
        4. 8.2.2.4 Flying Capacitor
        5. 8.2.2.5 Output Capacitor
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
        1. 11.1.1.1 Third-Party Products Disclaimer
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

7.3.7 Three-Level Buck Converter Theory of Operation

The three-level converter is a combination of a switched capacitor and a switched inductor circuit. Assuming the flying capacitor, CFLY, remains balanced at VIN/2, the VSW node can be presented with three different voltages: VIN, VIN/2, and GND. The gate driving scheme is similar to a two-phase buck converter. The outer FETs (QHSA and QLSA) are driven with a complimentary signal with duty cycle D = VOUT/VIN. The inner FETs (QHSB and QLSB) are driven with a second complimentary signal of equal duty cycle, but phase shifted by 180°. By employing this driving scheme, there is a smooth transition around 50% duty ratio, where the VSW node moves from presenting GND and VIN/2 to presenting VIN and VIN/2.

The three-level can achieve higher efficiency which cannot be easily obtained using traditional buck converter. The high efficiency is due to reduced inductor ripple (volt-seconds), reduced switching loss, and use of a compact inductor with lower DCR. The device integrates low RDSON FETs to optimize conduction loss. It also integrates control circuit to monitor CFLY stability and pre-conditioning.

BQ25910 threelevelbuck_lvs.gifFigure 14. (a) Three-Level Buck Converter Circuit, (b) Time-Domain VSW and VO Waveforms, and (c) Inductor Current Ripple Comparison Across Duty Ratio
BQ25910 buckdutyR0-50_lvsdu0.gifFigure 15. Three-Level Buck Converter States for Duty Ratios < 0.50
BQ25910 buckdutyL0-50_lvsdu0.gifFigure 16. Three-Level Buck Converter States for Duty Ratios > 0.50