Digital controller for wireless battery charger transmitters for wearable and smart watches applications

The STWBC-WA is STMicroelectronics’ wireless battery charger transmitter application optimized for wearable usage.

Thanks to its 5 V native supply, the STWBC-WA device is ideal to operate with USB power supplies.

Wireless battery charging systems replace the traditional power supply cable by means of electromagnetic induction between a transmitting pad or dongle (TX) and a battery-powered unit (RX), such as a smartwatch or sports gear.

The power transmitter unit is responsible for controlling the transmitting coil and generating the correct amount of power requested by the receiver unit. The receiver unit continuously provides the transmitter the correct power level requested, by modulating the transmitter carrier through controlled resistive or capacitive insertion. Generating the correct amount of power guarantees the highest level of end-to-end efficiency due to reduced energy waste. It also helps to maintain a lower operational temperature.

The digital wireless battery transmitter can adapt to the amount of energy transferred by the coil by modulating the frequency, duty cycles or coil input voltage.

Key Features

  • Digital controller for wireless battery charger transmitters
  • Optimized for < 3 W applications
    • Smartwatches and healthcare
    • Internet of Things (IoT) battery-powered smart devices
    • Remote controllers
  • Cost effective half-bridge topology with integrated drivers
  • Optional full-bridge configuration for 3 W applications
  • VIN range: 3 V to 5.5 V
    • Supports USB VIN
  • Active presence detector
  • Parametric customization via graphical interface
  • 2 firmware options:
    • Turnkey solution for quick design
    • APIs available for application customization
  • Peripherals available via APIs
    • ADC, with 10-bit precision
    • UART
    • I2 C master fast/slow speed rate
    • GPIOs
  • Memory
    • Flash and EEPROM with read-while-write (RWW) and Error Correction Code (ECC)
    • Program memory: 32 Kbytes Flash; data retention: 15 years at 85 °C after 10 kcycles at 25 °C
    • Data memory: 1 Kbyte true data EEPROM; data retention: 15 years at 85 °C after 100 kcycles at 85 °C
    • RAM: 6 Kbytes
  • Transmitter reference design:
    • Evaluation board order code: STEVAL-ISB038V1T
    • 2-layer PCBs
    • Active object detection
    • Graphical user interface for application monitoring
    • Interoperable with receiver: STEVAL-ISB038V1R
  • Operating temperature
    • -40 °C up to 105 °C
  • Package
    • VFQFPN32


Technical Documentation

Product Specifications
Description Version Size
DS11797 DS11797: Digital controller for wireless battery charger transmitters for wearable and smartwatch applications 1.0 787 KB

Publications and Collaterals

Description Version Size
Wireless power kit for IoT devices 07.2017 729 KB
Selection Guides
Description Version Size
Linear and Switching Voltage Regulators Selection Guide 3.0 370 KB
Description Version Size
Brochure Power management guide 05.2016 3 MB

Tools and Software

Embedded Software
Evaluation Tool Software
Evaluation Tools
Solution Evaluation Tools
Support & Community

Sample & Buy

Part Number Package Packing Type Marketing Status Unit Price (US$) * Quantity ECCN (EU) ECCN (US) Country of Origin More info Order from ST Order from Distributors
STWBC-WATR VFQFPN 32 5x5x1.0 Tape And Reel Active 2.825 1000 NEC EAR99 PHILIPPINES MORE INFO No availability reported, please contact our Sales office

(*) Suggested Resale Price per unit (USD) for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office  or our Distributors

Quality & Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
STWBC-WATR ActiveVFQFPN 32 5x5x1.0IndustrialEcopack2 0 0
STWBC-WA ActiveVFQFPN 32 5x5x1.0IndustrialEcopack2 0 0

(**) The Material Declaration forms available on may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.