SLUA748A December   2015  – April 2016 BQ25120 , BQ51003 , TPS61046 , TPS61240 , TPS62743

 

  1.   Trademarks
  2.   Power Management Reference Design for a Wearable Device with Wireless Charging Using the bq51003 and bq25120
    1. 1 Wearable Power Design
      1. 1.1 Wireless Charging Input
      2. 1.2 Battery Charger, MCU, Radio, and Sensor Power
      3. 1.3 Second Buck Output for MCU, Radio or Sensor
    2. 2 PMOLED Display Power Design
    3. 3 Heart Rate Monitor or e-Ink Power Design
    4. 4 Layout Guidelines for Wearable Design
      1. 4.1 Wireless Receiver (bq51003)
      2. 4.2 Linear Charger (bq25120)
      3. 4.3 Buck Converter (TPS62743/6)
      4. 4.4 Boost Converters (TPS61046 and TPS61240)
      5. 4.5 General Considerations
    5. 5 References
  3. AExperimental Results
    1. A.1 Experimental Results
  4.   Revision History

1.1 Wireless Charging Input

A large number of low-power wearable devices such as smart watches, fitness wrist bands and headphones are adopting wireless charging. The BQ51003 is an advanced, integrated receiver tailored for wearable applications. A standard Qi-compliant design will deliver 5W with a 50-mm coil. Figure 3 is modified from a Qi-compliant design with a smaller 30-mm coil and adjustable 500 mW to 1500 mW capabilities. When used with a Qi-compliant wireless transmitter, the RX_OUT supplies the input to a Li-Ion charger, in this case the bq25120. This better matches the wearable form factor and battery requirements, and is optimized for the device to stay cooler during power transfer.

schematic_wireless_charging_slua748.gifFigure 3. Schematic of Wireless Charging Receiver Using the bq51003