AirFuel demo sends 33W of wireless power

August 11, 2017 // By Graham Prophet
Using its own gallium nitride (GaN) FETs, Efficient Power Conversion Corporation (EPC) has configured a complete class 4 wireless power charging kit that can transmit up to 33 W while operating at 6.78 MHz (the lowest ISM band).

The EPC9120 simplifies the evaluation process of using eGaN FETs for efficient wireless power transfer with full power efficiency between 80% and 90% under various operating conditions.


The EPC9120 wireless power system consists of four boards:

  • Source Board (Transmitter or Power Amplifier) EPC9512
  • Class 4 Air Fuel compliant Source Coil (Transmit Coil)
  • Category 4 AirFuel compliant Device Coil with rectifier and DC smoothing capacitor
  • Category 3 AirFuel compliant Device Coil with rectifier and DC smoothing capacitor.

The popularity of highly resonant wireless power transfer is increasing rapidly, particularly for applications targeting portable device charging. The end applications are varied and evolving quickly from cell phone charging, to handheld tablets, and laptop computers. Delivering up to 33 W supports all of these applications.

The source board is an efficient Zero Voltage Switching (ZVS), Class-D amplifier configured in an optional half-bridge topology (for single-ended configuration) or default full-bridge topology (for differential configuration), and includes the gate driver(s), oscillator, and feedback controller for the pre-regulator. This allows for compliance testing operating to the AirFuel class 4 standard over a wide load range. This amplifier board is available separately as EPC9512 for evaluation in existing customer systems.

The source coil , as well as the device coil , are AirFuel compliant and have been pre-tuned to operate at 6.78 MHz. The source coil is class 4 and the device coils are category 3 and category 4 compliant.

The EPC9120 wireless power transfer demonstration systems are priced at $907.20. The EPC9512 amplifier board can also be purchased separately and is priced at $390.00. (Both at distributor Digi-Key.)