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

7.3.6 Temperature Regulation (TREG)

In high power application, monitoring and controlling external component temperature can enhance reliability by limiting the total converter power under certain scenarios. The CMPIN_TR pin can be configured as temperature regulation feedback sensing pin when CMPIN_TR_SELECT=1b. This pin is the temperature feedback pin temperature regulation loop. The external voltage divider circuit is shown in Figure 7-5 consisting of RS and NTC resistor RTH. External NTC is placed where temperature is regulated (for example charger power stage) and generates feedback voltage on the CMPIN_TR pin based on temperature variation. When the temperature is lower than target, the voltage must be above 1.2V, temperature regulation is not effective and TREG_STAT=0b. As temperature increases, CMPIN_TR pin voltage drops to VTREG=1.2V or lower, converter begin to reduce converter current and regulate the CMPIN_TR voltage to stay at 1.2V and set TREG_STAT=1b which is locked until host read or REG_RESET bit action.

To enable temperature regulation feature:

  • Set CMPIN_TR_SELECT=1b to configure CMPIN_TR_SELECT pin as temperature regulation feedback pin.
  • Make sure AC is plugged in and charge is enabled CHARGE_CURRENT() is non-zero and CHRG_INHIBIT=0b).
  • Set EN_TREG=1b to enable temperature regulation and pull CMPOUT pin to GND.

The RS and NTC resistor RTH network generate some quiescent current which is not always negligible under light load. To reduce quiescent current under light load, instead of pull down RTH to GND locally at power stage, we can pull down through CMPOUT pin shown in Figure 7-5. Under either TREG is enabled (CMPIN_TR_SELECT=1b & EN_TREG=1b) or thermal PROCHOT channel is enabled (CMPIN_TR_SELECT=1b & PP_THERMAL=1b), then CMPOUT pin is pulled down to GND to generate sensing voltage on CMPIN_TR pin. However under light load both TREG and PP_THERMAL can be both disabled (CMPIN_TR_SELECT=1b & EN_TREG=0b & PP_THERMAL=0b), then device keeps the CMPOUT pin high impedance to reduce quiescent current flow through voltage divider network.

BQ25785 Recommended Configuration for CMPIN_TR Temperature RegulationFigure 7-5 Recommended Configuration for CMPIN_TR Temperature Regulation

The target temperature regulation value can be chosen through configuring RS fixed resistor. A 10k NTC thermistor(ERTJ0EG103FA) is recommended in this application, corresponding RS fixed value can be calculated through equation below. The RS corresponding value at 60ºC/80ºC/100ºC TREG refers to Table 7-4. The corresponding CMPIN_TR pin voltage with swept temperature under 60ºC/80ºC/100ºC TREG configuration can be found in Figure 7-6. Based on this graph, besides temperature regulation function, the NTC temperature can also be measured through CMPIN_TR pin voltage. The device has a dedicated CMPIN_TR pin voltage ADC channel which can be enabled through setting EN_ADC_CMPIN=1b.

There is a dedicated PROCHOT profile in case regulation target gets overheat more than TREG target. The profile can enabled through setting PP_THERMAL=1b by referring to PROCHOT Profile.

Equation 1. R S = 5 V - 1.2 V 1.2 V R N T C at T R E G
Table 7-4 CMPIN_TR Pin RC Network Configuration Reference Based on ERTJ0EG103FA NTC
RSTREG TEMPERATURE
9.53kΩ60ºC
5.23kΩ80ºC
3.01kΩ100ºC
BQ25785 CMPIN_TR Pin Voltage vs Temperature Under Different Regulation Target (60°C, 80°C, and 100°C)Figure 7-6 CMPIN_TR Pin Voltage vs Temperature Under Different Regulation Target (60°C, 80°C, and 100°C)