SLUSG46 March   2026 BQ25785

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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 BQ2578X
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Power-Up Sequence
      2. 7.3.2  MODE Pin Detection
      3. 7.3.3  REGN Regulator (REGN LDO)
      4. 7.3.4  Independent Comparator Function
      5. 7.3.5  Battery Charging Management
        1. 7.3.5.1 Autonomous Charging Cycle
        2. 7.3.5.2 Battery Charging Profile
        3. 7.3.5.3 Charging Termination
        4. 7.3.5.4 Charging Safety Timer
      6. 7.3.6  Temperature Regulation (TREG)
      7. 7.3.7  Vmin Active Protection (VAP) When Battery Only Mode
      8. 7.3.8  Two Level Battery Discharge Current Limit
      9. 7.3.9  Fast Role Swap Feature
      10. 7.3.10 CHRG_OK Indicator
      11. 7.3.11 Input and Charge Current Sensing
      12. 7.3.12 Input Current and Voltage Limit Setup
      13. 7.3.13 Battery Cell Configuration
      14. 7.3.14 Device HIZ State
      15. 7.3.15 USB On-The-Go (OTG)
      16. 7.3.16 Quasi-dual Phase Converter Operation
      17. 7.3.17 Continuous Conduction Mode (CCM)
      18. 7.3.18 Pulse Frequency Modulation (PFM)
      19. 7.3.19 Switching Frequency and Dithering Feature
      20. 7.3.20 Current and Power Monitor
        1. 7.3.20.1 High-Accuracy Current Sense Amplifier (IADPT and IBAT)
        2. 7.3.20.2 High-Accuracy Power Sense Amplifier (PSYS)
      21. 7.3.21 Input Source Dynamic Power Management
      22. 7.3.22 Integrated 16-Bit ADC for Monitoring
      23. 7.3.23 Input Current Optimizer (ICO)
      24. 7.3.24 Two-Level Adapter Current Limit (Peak Power Mode)
      25. 7.3.25 Processor Hot Indication
        1. 7.3.25.1 PROCHOT During Low Power Mode
        2. 7.3.25.2 PROCHOT Status
      26. 7.3.26 Device Protection
        1. 7.3.26.1  Watchdog Timer (WD)
        2. 7.3.26.2  Input Overvoltage Protection (ACOV)
        3. 7.3.26.3  Input Overcurrent Protection (ACOC)
        4. 7.3.26.4  System Overvoltage Protection (SYSOVP)
        5. 7.3.26.5  System Voltage Maximum Regulation (SYS_MAX)
        6. 7.3.26.6  Battery Overvoltage Protection (BATOVP)
        7. 7.3.26.7  Battery Charge Overcurrent Protection (BATCOC)
        8. 7.3.26.8  Battery Discharge Overcurrent Protection (BATDOC)
        9. 7.3.26.9  BATFET Charge Current Clamp Protection Under LDO Regulation Mode
        10. 7.3.26.10 Sleep Comparator Protection Between VBUS and ACP_A (SC_VBUSACP)
        11. 7.3.26.11 REGN Power Good Protection (REGN_PG)
        12. 7.3.26.12 System Under Voltage Lockout (VSYS_UVP) and Hiccup Mode
        13. 7.3.26.13 OTG Mode Over Voltage Protection (OTG_OVP)
        14. 7.3.26.14 OTG Mode Under Voltage Protection (OTG_UVP)
        15. 7.3.26.15 Thermal Shutdown (TSHUT)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Forward Mode
        1. 7.4.1.1 System Voltage Regulation with Narrow VDC Architecture
        2. 7.4.1.2 Battery Charging
      2. 7.4.2 USB On-The-Go Mode
      3. 7.4.3 Pass Through Mode (PTM)-Patented Technology
      4. 7.4.4 Learn Mode
    5. 7.5 Programming
      1. 7.5.1 SMBus Interface
        1. 7.5.1.1 SMBus Write-Word and Read-Word Protocols
        2. 7.5.1.2 Timing Diagrams
    6. 7.6 BQ25785 Register Map
    7. 7.7 BQ25785 Registers
  9. 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 Input Snubber and Filter for Voltage Spike Damping
        2. 8.2.2.2 ACP-ACN Input Filter
        3. 8.2.2.3 Inductor Selection
        4. 8.2.2.4 Input Capacitor
        5. 8.2.2.5 Output Capacitor
        6. 8.2.2.6 Power MOSFETs Selection
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
        1. 8.4.2.1 Layout Example Reference Top View
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.3.5.1 Autonomous Charging Cycle

When autonomous battery charging is enabled (EN_AUTO_CHG=1b, CHRG_INHIBIT=0b and CHARGE_CURRENT() register is not 0mA), the device autonomously completes a charging cycle without host involvement. The battery charging parameters can be programmed by CHARGE_VOLTAGE() and CHARGE_CURRENT(). The host can always control the charging operation and optimize the charging parameters by writing to the corresponding registers.

Table 7-2 Li-Ion Charging Parameter Default Settings
DEFAULT MODECHARGER
Charge StagesPrecharge → Fast Charge (CC) → Taper Charge (CV) → Termination → Recharge
Cell count (n_cell)Set by CELL_BATPRES pin
Charge Voltage (CHARGE_VOLTAGE())4.2V / Cell
Charge Current(CHARGE_CURRENT())0A(Need host configuration)
Termination Current (ITERM)256mA
Recharge Voltage (VRECHG)CHARGE_VOLTAGE()-(Set by CELL_BATPRES pin)
Pre-Charge Current(IPRECHG)384mA
Safety Timer12 hours

An autonomous charge cycle starts when the following conditions are valid:

  • Converter starts up
  • Battery autonomous charge is enabled (EN_AUTO_CHG = 1b)
  • CHARGE_CURRENT() register is not 0mA
  • CHRG_INHIBIT bit is not 1b
  • No SYSOVP/VSYS_UVP/ACOC/TSHUT/BATOVP/BATDOC/SC_VBUSACP/Force converter off faults
  • No safety timer fault

The device automatically terminates the charging cycle when the charging current is below termination threshold, charge voltage is above recharge threshold, and device is not in DPM mode. When a full battery voltage is discharged below recharge threshold (threshold selectable via VRECHG[3:0] bits), the device automatically starts a new charging cycle. After the charge is terminated automatically, changing CHRG_INHIBIT bit from 1b to 0b or CHARGE_CURRENT() from 0A to non zero value can initiate a new charging cycle.

The status register (CHRG_STAT) indicates the different charging phases as:

  • 000 – Not Charging
  • 001 – Trickle Charge (VBAT < VBAT_SHORT)
  • 010 – Pre-charge (VBAT_SHORT < VBAT < VSYS_MIN() setting)
  • 011 – Fast-charge (CC mode)
  • 100 – Taper Charge (CV mode)
  • 101 – Reserved
  • 110 – Reserved
  • 111 – Charge Termination Done