SLUSD20B july   2018  – april 2023 BQ25710

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Timing Requirements
    7. 8.7 Typical Characteristics
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Power-Up from Battery Without DC Source
      2. 9.3.2  Vmin Active Protection (VAP) when Battery only Mode
      3. 9.3.3  Power-Up From DC Source
        1. 9.3.3.1 CHRG_OK Indicator
        2. 9.3.3.2 Input Voltage and Current Limit Setup
        3. 9.3.3.3 Battery Cell Configuration
        4. 9.3.3.4 Device Hi-Z State
      4. 9.3.4  USB On-The-Go (OTG)
      5. 9.3.5  Converter Operation
        1. 9.3.5.1 Inductance Detection Through IADPT Pin
        2. 9.3.5.2 Continuous Conduction Mode (CCM)
        3. 9.3.5.3 Pulse Frequency Modulation (PFM)
      6. 9.3.6  Current and Power Monitor
        1. 9.3.6.1 High-Accuracy Current Sense Amplifier (IADPT and IBAT)
        2. 9.3.6.2 High-Accuracy Power Sense Amplifier (PSYS)
      7. 9.3.7  Input Source Dynamic Power Manage
      8. 9.3.8  Two-Level Adapter Current Limit (Peak Power Mode)
      9. 9.3.9  Processor Hot Indication
        1. 9.3.9.1 PROCHOT During Low Power Mode
        2. 9.3.9.2 PROCHOT Status
      10. 9.3.10 Device Protection
        1. 9.3.10.1 Watchdog Timer
        2. 9.3.10.2 Input Overvoltage Protection (ACOV)
        3. 9.3.10.3 Input Overcurrent Protection (ACOC)
        4. 9.3.10.4 System Overvoltage Protection (SYSOVP)
        5. 9.3.10.5 Battery Overvoltage Protection (BATOVP)
        6. 9.3.10.6 Battery Short
        7. 9.3.10.7 System Short Hiccup Mode
        8. 9.3.10.8 Thermal Shutdown (TSHUT)
    4. 9.4 Device Functional Modes
      1. 9.4.1 Forward Mode
        1. 9.4.1.1 System Voltage Regulation with Narrow VDC Architecture
        2. 9.4.1.2 Battery Charging
      2. 9.4.2 USB On-The-Go
      3. 9.4.3 Pass Through Mode (PTM)
    5. 9.5 Programming
      1. 9.5.1 SMBus Interface
        1. 9.5.1.1 SMBus Write-Word and Read-Word Protocols
        2. 9.5.1.2 Timing Diagrams
    6. 9.6 Register Map
      1. 9.6.1  Setting Charge and PROCHOT Options
        1. 9.6.1.1 ChargeOption0 Register (SMBus address = 12h) [reset = E70Eh]
        2. 9.6.1.2 ChargeOption1 Register (SMBus address = 30h) [reset = 0211h]
        3. 9.6.1.3 ChargeOption2 Register (SMBus address = 31h) [reset = 02B7h]
        4. 9.6.1.4 ChargeOption3 Register (SMBus address = 32h) [reset = 0030h]
        5. 9.6.1.5 ProchotOption0 Register (SMBus address = 33h) [reset = 4A65h]
        6. 9.6.1.6 ProchotOption1 Register (SMBus address = 34h) [reset = 81A0h]
        7. 9.6.1.7 ADCOption Register (SMBus address = 35h) [reset = 2000h]
      2. 9.6.2  Charge and PROCHOT Status
        1. 9.6.2.1 ChargerStatus Register (SMBus address = 20h) [reset = 0000h]
        2. 9.6.2.2 ProchotStatus Register (SMBus address = 21h) [reset = A800h]
      3. 9.6.3  ChargeCurrent Register (SMBus address = 14h) [reset = 0000h]
        1. 9.6.3.1 Battery Precharge Current Clamp
      4. 9.6.4  MaxChargeVoltage Register (SMBus address = 15h) [reset value based on CELL_BATPRESZ pin setting]
      5. 9.6.5  MinSystemVoltage Register (SMBus address = 3Eh) [reset value based on CELL_BATPRESZ pin setting]
        1. 9.6.5.1 System Voltage Regulation
      6. 9.6.6  Input Current and Input Voltage Registers for Dynamic Power Management
        1. 9.6.6.1 Input Current Registers
          1. 9.6.6.1.1 IIN_HOST Register With 10-mΩ Sense Resistor (SMBus address = 3Fh) [reset = 4100h]
          2. 9.6.6.1.2 IIN_DPM Register With 10-mΩ Sense Resistor (SMBus address = 022h) [reset = 4100h]
          3. 9.6.6.1.3 InputVoltage Register (SMBus address = 3Dh) [reset = VBUS-1.28V]
      7. 9.6.7  OTGVoltage Register (SMBus address = 3Bh) [reset = 0000h]
      8. 9.6.8  OTGCurrent Register (SMBus address = 3Ch) [reset = 0000h]
      9. 9.6.9  ADCVBUS/PSYS Register (SMBus address = 23h)
      10. 9.6.10 ADCIBAT Register (SMBus address = 24h)
      11. 9.6.11 ADCIINCMPIN Register (SMBus address = 25h)
      12. 9.6.12 ADCVSYSVBAT Register (SMBus address = 26h)
      13. 9.6.13 ID Registers
        1. 9.6.13.1 ManufactureID Register (SMBus address = FEh) [reset = 0040h]
        2. 9.6.13.2 Device ID (DeviceAddress) Register (SMBus address = FFh) [reset = 0h]
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 ACP-ACN Input Filter
        2. 10.2.2.2 Inductor Selection
        3. 10.2.2.3 Input Capacitor
        4. 10.2.2.4 Output Capacitor
        5. 10.2.2.5 Power MOSFETs Selection
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
      1. 12.2.1 Layout Example Reference Top View
      2. 12.2.2 Inner Layer Layout and Routing Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Third-Party Products Disclaimer
    2. 13.2 Documentation Support
      1. 13.2.1 Related Documentation
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Support Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

10.2.2.5 Power MOSFETs Selection

Four external N-channel MOSFETs are used for a synchronous switching battery charger. The gate drivers are internally integrated into the IC with 6 V of gate drive voltage. 30 V or higher voltage rating MOSFETs are preferred for 19 V - 20 V input voltage.

Figure-of-merit (FOM) is usually used for selecting proper MOSFET based on a tradeoff between the conduction loss and switching loss. For the top side MOSFET, FOM is defined as the product of a MOSFET's on-resistance, RDS(ON), and the gate-to-drain charge, QGD. For the bottom side MOSFET, FOM is defined as the product of the MOSFET's on-resistance, RDS(ON), and the total gate charge, QG.

Equation 6. FOMtop = RDS(on) x QGD; FOMbottom = RDS(on) x QG

The lower the FOM value, the lower the total power loss. Usually lower RDS(ON) has higher cost with the same package size.

The top-side MOSFET loss includes conduction loss and switching loss. It is a function of duty cycle (D=VOUT/VIN), charging current (ICHG), MOSFET's on-resistance (RDS(ON)), input voltage (VIN), switching frequency (fS), turn on time (ton) and turn off time (toff):

Equation 7. GUID-A1009448-B18B-4649-BDF4-68A08F4EE6C7-low.gif

The first item represents the conduction loss. Usually MOSFET RDS(ON) increases by 50% with 100°C junction temperature rise. The second term represents the switching loss. The MOSFET turn-on and turn-off times are given by:

Equation 8. GUID-66D54DC8-331A-4159-84C7-3FAB15FEA334-low.gif

where Qsw is the switching charge, Ion is the turn-on gate driving current and Ioff is the turn-off gate driving current. If the switching charge is not given in MOSFET datasheet, it can be estimated by gate-to-drain charge (QGD) and gate-to-source charge (QGS):

Equation 9. GUID-9BC92E23-C265-4F71-9A3C-B409AED5E622-low.gif

Gate driving current can be estimated by REGN voltage (VREGN), MOSFET plateau voltage (Vplt), total turn-on gate resistance (Ron) and turn-off gate resistance (Roff) of the gate driver:

Equation 10. GUID-2A574F33-73D8-4CE8-BFE8-F907B6945821-low.gif

The conduction loss of the bottom-side MOSFET is calculated with the following equation when it operates in synchronous continuous conduction mode:

Equation 11. Pbottom = (1 - D) x ICHG2 x RDS(on)

When charger operates in non-synchronous mode, the bottom-side MOSFET is off. As a result all the freewheeling current goes through the body-diode of the bottom-side MOSFET. The body diode power loss depends on its forward voltage drop (VF), non-synchronous mode charging current (INONSYNC), and duty cycle (D).

Equation 12. PD = VF x INONSYNC x (1 - D)

The maximum charging current in non-synchronous mode can be up to 0.25 A for a 10-mΩ charging current sensing resistor or 0.5 A if battery voltage is below 2.5 V. The minimum duty cycle happens at lowest battery voltage. Choose the bottom-side MOSFET with either an internal Schottky or body diode capable of carrying the maximum non-synchronous mode charging current.