SLUSBC8C December   2013  – July 2018


  1. Features
  2. Applications
  3. Description
    1.     Wireless Power Consortium (WPC or Qi) Inductive Power System
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
    1.     Pin Functions
  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 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
      1. 8.1.1 A Brief Description of the Wireless System
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Details of a Qi Wireless Power System and bq51003 Power Transfer Flow Diagrams
      2. 8.3.2  Dynamic Rectifier Control
      3. 8.3.3  Dynamic Efficiency Scaling
      4. 8.3.4  RILIM Calculations
      5. 8.3.5  Input Overvoltage
      6. 8.3.6  Adapter Enable Functionality and EN1/EN2 Control
      7. 8.3.7  End Power Transfer Packet (WPC Header 0x02)
      8. 8.3.8  Status Outputs
      9. 8.3.9  WPC Communication Scheme
      10. 8.3.10 Communication Modulator
      11. 8.3.11 Adaptive Communication Limit
      12. 8.3.12 Synchronous Rectification
      13. 8.3.13 Temperature Sense Resistor Network (TS)
      14. 8.3.14 3-State Driver Recommendations for the TS-CTRL Pin
      15. 8.3.15 Thermal Protection
      16. 8.3.16 WPC v1.2 Compliance – Foreign Object Detection
    4. 8.4 Device Functional Modes
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 bq51003 Wireless Power Receiver Used as a Power Supply
        1. Design Requirements
        2. Detailed Design Procedure
          1. Using the bq51003 as a Wireless Power Supply
          2. Series and Parallel Resonant Capacitor Selection
          3. COMM, CLAMP, and BOOT Capacitors
          4. Control Pins and CHG
          5. Current Limit and FOD
          6. RECT and OUT Capacitance
        3. Application Curves
      2. 9.2.2 Dual Power Path: Wireless Power and DC Input
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

Details of a Qi Wireless Power System and bq51003 Power Transfer Flow Diagrams

The bq51003 integrates a fully compliant WPC v1.2 communication algorithm to streamline receiver designs (no extra software development required). Other unique algorithms such as Dynamic Rectifier Control are also integrated to provide best-in-class system performance. This section provides a high-level overview of these features by illustrating the wireless power transfer flow diagram from start-up to active operation.

During start-up operation, the wireless power receiver must comply with proper handshaking to be granted a power contract from the Tx. The Tx initiates the hand shake by providing an extended digital ping. If an Rx is present on the Tx surface, the Rx then provides the signal strength, configuration, and identification packets to the Tx (see volume 1 of the WPC specification for details on each packet). These are the first three packets sent to the Tx. The only exception is if there is a true shutdown condition on the EN1/EN2, AD, or TS-CTRL pins where the Rx will shut down the Tx immediately. See Table 5 for details. Once the Tx has successfully received the signal strength, configuration, and identification packets, the Rx will be granted a power contract and is then allowed to control the operating point of the power transfer. With the use of the bq51003 Dynamic Rectifier Control algorithm, the Rx will inform the Tx to adjust the rectifier voltage above 7 V prior to enabling the output supply. This method enhances the transient performance during system start-up. See Figure 18 for the start-up flow diagram details.

bq51003 wireless_power_start_flowchart_lusbc8.gifFigure 18. Wireless Power Start-Up Flow Diagram

Once the start-up procedure has been established, the Rx will enter the active power transfer stage. This is considered the main loop of operation. The Dynamic Rectifier Control algorithm will determine the rectifier voltage target based on a percentage of the maximum output current level setting (set by KIMAX and the ILIM resistance to GND). The Rx will send control error packets to converge on these targets. As the output current changes, the rectifier voltage target will dynamically change. As a note, the feedback loop of the WPC system is relatively slow where it can take up to 90 ms to converge on a new rectifier voltage target. It should be understood that the instantaneous transient response of the system is open loop and dependent on the Rx coil output impedance at that operating point. The main loop will also determine if any conditions in Table 5 are true to discontinue power transfer. See Figure 19 which illustrates the active power transfer loop.

bq51003 active_power_trans_flowchart_slusb62.gifFigure 19. Active Power Transfer Flow Diagram

Another requirement of the WPC v1.2 specification is to send the measured received power. This task is enabled on the IC by measuring the voltage on the FOD pin which is proportional to the output current and can be scaled based on the choice of the resitor to ground on the FOD pin.