SLUSAK9B September   2011  – April 2015

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Typical Characteristics
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Adapter Detect and ACOK Output
      2. 9.3.2  Adapter Overvoltage (ACOVP)
      3. 9.3.3  System Power Selection
      4. 9.3.4  Automatic Internal Soft-Start Charger Current
      5. 9.3.5  Converter Operation
      6. 9.3.6  Input Overcurrent Protection (ACOC)
      7. 9.3.7  Charge Overcurrent Protection (CHGOCP)
      8. 9.3.8  Battery Overvoltage Protection (BATOVP)
      9. 9.3.9  Battery Shorted to Ground (BATLOWV)
      10. 9.3.10 Thermal Shutdown Protection (TSHUT)
      11. 9.3.11 Inductor Short, MOSFET Short Protection
    4. 9.4 Device Functional Modes
      1. 9.4.1 Enable and Disable Charging
      2. 9.4.2 Continuous Conduction Mode (CCM)
      3. 9.4.3 Discontinuous Conduction Mode (DCM)
    5. 9.5 Programming
      1. 9.5.1 SMBus Interface
      2. 9.5.2 Battery LEARN Cycle
      3. 9.5.3 Charge Time-out
      4. 9.5.4 High-Accuracy Current-Sense Amplifier
      5. 9.5.5 EMI Switching Frequency Adjust
    6. 9.6 Register Maps
      1. 9.6.1 Battery-Charger Commands
      2. 9.6.2 Setting Charger Options
      3. 9.6.3 Charge Options Register [reset = 0x12H]
      4. 9.6.4 Setting the Charge Current
      5. 9.6.5 Setting the Charge Voltage
      6. 9.6.6 Setting Input Current
      7. 9.6.7 Support Turbo Boost Function
  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 Negative Output Voltage Protection
        2. 10.2.2.2 Reverse Input Voltage Protection
        3. 10.2.2.3 Reduce Battery Quiescent Current
        4. 10.2.2.4 Inductor Selection
        5. 10.2.2.5 Input Capacitor
        6. 10.2.2.6 Output Capacitor
        7. 10.2.2.7 Power MOSFETs Selection
        8. 10.2.2.8 Input Filter Design
        9. 10.2.2.9 bq24735 Design Guideline
      3. 10.2.3 Application Curves
    3. 10.3 System Examples
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout 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 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • Adapter and Battery Provide Power to System Together to Support Intel® CPU Turbo Boost Mode
  • SMBus Host-Controlled NMOS-NMOS Synchronous Buck Converter With Programmable 615-, 750-, and 885-kHz Switching Frequencies
  • Automatic N-Channel MOSFET Selection of System Power Source From Adapter or Battery Driven by Internal Charge Pumps
  • Enhanced Safety Features for Overvoltage Protection, Overcurrent Protection, Battery, Inductor and MOSFET Short-Circuit Protection
  • Programmable Input Current, Charge Voltage, Charge Current Limits
    • ±0.5% Charge Voltage Accuracy up to 19.2 V
    • ±3% Charge Current Accuracy up to 8.128 A
    • ±3% Input Current Accuracy up to 8.064 A
    • ±2% 20× Adapter Current or Charge Current Amplifier Output Accuracy
  • Programmable Battery Depletion Threshold, and Battery LEARN Function
  • Programmable Adapter Detection and Indicator
  • Integrated Loop Compensation and Soft Start
  • Real-Time System Control on ILIM Pin to Limit Charge Current
  • AC Adapter Operating Range: 4.5 V to 24 V
  • 5-µA Off-State Battery Discharge Current
  • 0.65 mA (0.8 mA Max) Adapter Standby Quiescent Current

2 Applications

  • Portable Notebook Computers, UMPC, Ultra-Thin Notebooks, and Netbooks
  • Handheld Terminals
  • Industrial and Medical Equipment
  • Portable Equipment

3 Description

The bq24735 device is a high-efficiency, synchronous battery charger, offering low component count for space-constrained, multichemistry battery charging applications. The bq24735 device supports turbo boost by allowing battery discharge energy to the system when system power demand is temporarily higher than the adapter maximum power level so the adapter will not crash.

The bq24735 device uses two charge pumps to separately drive N-channel MOSFETs (ACFET, RBFET, and BATFET) for automatic system power source selection.

SMBus controlled input current, charge current, and charge voltage digital-to-analog converters (DACs) allow for very high-regulation accuracies that can be easily programmed by the system power management microcontroller.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
bq24735 VQFN (20) 3.50 mm × 3.50 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Simplified Application Diagram

bq24735 fp_schem_lusak9.gif