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

Adapter Enable Functionality and EN1/EN2 Control

Figure 38 is an example application that shows the bq51003 used as a wireless power receiver that can power mutliplex between wired or wireless power for the down-system electronics. In the default operating mode pins EN1 and EN2 are low, which activates the adapter enable functionality. In this mode, if an adapter is not present the AD pin will be low, and AD-EN pin will be pulled to the higher of the OUT and AD pins so that the PMOS between OUT and AD will be turned off. If an adapter is plugged in and the voltage at the AD pin goes above
3.6 V then wireless charging is disabled and the AD-EN pin will be pulled approximately 4 V below the AD pin to connect AD to the secondary charger. The difference between AD and AD-EN is regulated to a maximum of 7 V to ensure the VGS of the external PMOS is protected.

The EN1 and EN2 pins include internal 200-kΩ pulldown resistors, so that if these pins are not connected bq51003 defaults to AD-EN control mode. However, these pins can be pulled high to enable other operating modes as described in Table 3:

Table 3. Adapter Enable Functionality

0 0 Adapter control enabled. If adapter is present then secondary charger is powered by adapter, otherwise wireless charging is enabled when wireless power is available. Communication current limit is enabled.
0 1 Disables communication current limit.
1 0 AD-EN is pulled low, whether or not adapter voltage is present. This feature can be used, for example, for USB OTG applications.
1 1 Adapter and wireless charging are disabled, that is, power will never be delivered by the OUT pin in this mode.

Table 4. EN1/EN2 Control

0 0 Enabled Priority(1) Disabled Enabled Not Sent to Tx
0 1 Priority(1) Enabled Disabled Disabled Not Sent to Tx
1 0 Disabled Enabled Enabled(2) N/A EPT 0x00, Unknown
1 1 Disabled Disabled Disabled N/A EPT 0x01, Charge Complete
If both wired and wireless power are present, wired power is given priority.
Allows for a boost-back supply to be driven from the output terminal of the Rx to the adapter port through the external back-to-back PMOS FET.

As described in Table 4, pulling EN2 high disables the adapter mode and only allows wireless charging. In this mode the adapter voltage will always be blocked from the OUT pin. An application example where this mode is useful is when USB power is present at AD, but the USB is in suspend mode so that no power can be taken from the USB supply. Pulling EN1 high enables the off-chip PMOS regardless of the presence of a voltage. This function can be used in USB OTG mode to allow a charger connected to the OUT pin to power the AD pin. Finally, pulling both EN1 and EN2 high disables both wired and wireless charging.


It is required to connect a back-to-back PMOS between AD and OUT so that voltage is blocked in both directions. Also, when AD mode is enabled no load can be pulled from the RECT pin as this could cause an internal device overvoltage in bq51003.