SLUSB42F July 2012  – June 2017


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Options
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1Absolute Maximum Ratings
    2. 7.2ESD Ratings
    3. 7.3Recommended Operating Conditions
    4. 7.4Thermal Information
    5. 7.5Electrical Characteristics
    6. 7.6Typical Characteristics
  8. Detailed Description
    1. 8.1Overview
      1. 8.1.1A Brief Description of the Wireless System
    2. 8.2Functional Block Diagram
    3. 8.3Feature Description
      1. 8.3.1Using the bq5105x as a Wireless Li-Ion/Li-Pol Battery Charger (With Reference to )
      2. 8.3.2Details of a Qi Wireless Power System and bq5105xB Power Transfer Flow Diagrams
      3. 8.3.3Battery Charge Profile
      4. 8.3.4Battery Charging Process
        1. Precharge Mode (VBAT ≤ VLOWV)
        2. Fast Charge Mode / Constant Voltage Mode
        3. Battery Charge Current Setting Calculations
          1. Calculations
          2. Calculations
        4. Battery-Charger Safety and JEITA Guidelines
          1. and bq51051B JEITA
          2. Modified JEITA
        5. Input Overvoltage
        6. End Power Transfer Packet (WPC Header 0x02)
        7. Status Output
        8. Communication Modulator
        9. Adaptive Communication Limit
        10. Rectification
        11. Temperature Sense (TS Function of the TS/CTRL Pin)
          1. Function
          2. Protection
        12. v1.2 Compatibility
    4. 8.4Device Functional Modes
  9. Application and Implementation
    1. 9.1Application Information
    2. 9.2Typical Application
      1. 9.2.1bq51050B Used as a Wireless Power Receiver and Li-Ion/Li-Pol Battery Charger
        1. Requirements
        2. Design Procedure
          1. and Parallel Resonant Capacitor Selection
          2., CLAMP and BOOT Capacitors
          3. and Termination Current
          4. Enable
          5. Indication and Power Capacitors
        3. Curves
      2. 9.2.2Application for Wired Charging
        1. Requirements
        2. Design Procedure
          1. Back-Back FET
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1Layout Guidelines
    2. 11.2Layout Example
  12. 12Device and Documentation Support
    1. 12.1Documentation Support
      1. 12.1.1Related Documentation
    2. 12.2Related Links
    3. 12.3Receiving Notification of Documentation Updates
    4. 12.4Community Resources
    5. 12.5Trademarks
    6. 12.6Electrostatic Discharge Caution
    7. 12.7Glossary
  13. 13Mechanical, Packaging, and Orderable Information


  • Single-Stage Wireless Power Receiver
    and Li-Ion/Li-Pol Battery Charger
    • Combines Wireless Power Receiver, Rectifier, and Battery Charger in a Single, Small Package
    • 4.20-V, 4.35-V, and 4.40-V Output Voltage Options
    • Supports a Charging Current up to 1.5 A
    • 93% Peak AC-DC Charging Efficiency
  • Robust Architecture
    • 20-V Maximum Input Voltage Tolerance,
      With Input Overvoltage Protection
    • Thermal Shutdown and Overcurrent Protection
    • Temperature Monitoring and Fault Detection
  • Compatible With WPC v1.2 Qi Industry Standard
  • Power Stage Output Tracks Rectifier and Battery Voltage to Ensure Maximum Efficiency Across the Full Charge Cycle
  • Available in Small DSGBA and VQFN Packages


  • Battery Packs
  • Cell Phones and Smart Phones
  • Headsets
  • Portable Media Players
  • Other Handheld Devices


The bq5105x device is a high-efficiency, Qi-compliant wireless power receiver with an integrated Li-Ion/Li-Pol battery charge controller for portable applications. The bq5105xB devices provide efficient AC-DC power conversion, integrates the digital controller required to comply with Qi v1.2 communication protocol, and provides all necessary control algorithms needed for efficient and safe Li-Ion and Li-Pol battery charging. Together with the bq500212A transmitter-side controller, the bq5105x enables a complete wireless power transfer system for direct battery charger solutions. By using near-field inductive power transfer, the receiver coil embedded in the portable device can pick up the power transmitted by transmitter coil. The AC signal from the receiver coil is then rectified and conditioned to apply power directly to the battery.  Global feedback is established from the receiver to the transmitter to stabilize the power transfer process.  This feedback is established by using the Qi v1.2 communication protocol.

The bq5105xB devices integrate a low-impedance synchronous rectifier, low-dropout regulator (LDO), digital control, charger controller, and accurate voltage and current loops in a single package.  The entire power stage (rectifier and LDO) use low-resistance N-MOSFETs (100-mΩ typical Rdson) to ensure high efficiency and low power dissipation.

Device Information(1)

VQFN (20)4.50 mm × 3.50 mm
DSBGA (28)3.00 mm × 1.90 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Schematic

bq51050B bq51051B bq51052B Pg1Sch.gif