New Industry Products

Digital Controller for Qi Multicoil Wireless Battery Charger Transmitters

September 11, 2018 by Paul Shepard

The is the digital controller for the wireless battery charger (WBC) transmitters (TX) from STMicroelectronics optimized for the extended power profile (EPP) Wireless Power Consortium (WPC) multi-coil applications up to 15W.

It offers the most flexible and efficient solution for controlling the power transfer to a receiver (RX) in WBC-enabled applications such as smartphones, tablets and other battery-powered devices that use the electromagnetic induction for recharging.

The TX is responsible for controlling the transmitting coil and generating the correct amount of power requested by the RX. The RX continuously provides the transmitter with the correct power level requested, by modulating the transmitter carrier through the controlled resistive or capacitive load. Generating the correct amount of power ensures the highest level of end-to-end efficiency due to reduced energy losses. It also helps maintaining a lower operational temperature.

The TX can adapt to the amount of energy transferred by the coil by modulating the frequency, duty cycle or amplitude of the PWM voltage on the transmitting coil.

The STWBC-MC is capable of bidirectional communication with the RX as specified by the WPC 1.2 protocol.

Key features include:

  • Digital controller for wireless battery charger transmitter
  • Multi-coil inductive transmitters optimized for:
    • Cell phones and smartphones
    • Tablets and phablets
    • Charging accessories
  • Support for Wireless Power Consortium (WPC) 1.2 EPP applications
    • Backward compatible with WPC BPP and 1.1 5W applications
  • Support for half-bridge topology with dc-dc
  • VIN range: 3V to 5.5V
    • Supports USB VIN
  • Active presence detector
  • Foreign object detection
  • Q-factor measurement
  • Parametric customization via GUI
  • Turnkey firmware solution
  • Peripherals
    • 10-bit ADC
    • UART interface
    • I2C 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: 20 years at 55°C after 1000 cycles at 55°C
    • Data memory: 1 Kbyte true data EEPROM; data retention: 20 years at 55°C after 1000 cycles at 85°C
    • RAM: 6 Kbytes
  • Transmitter reference design:
    • Multi-coil EPP topology
    • 2-layer PCBs
    • Active object detection
    • Graphical user interface for application monitoring
  • Operating temperature: -40°C up to 105°C
  • Package: VFQFPN32 5 x 5 mm