TransphormHighest Performance, Highest Reliability GaN


Open Frame 65 W Quasi-resonant flyback USB-C PD Power Adapter Reference Design using Transphorm SuperGaN Technology

The TDADP-TPH-ON-USBC-65W-RD is an open frame 65 W universal USB-C Power Delivery (PD) power adapter reference design. It meets USB PD 3.0 requirements for universal chargers supporting smartphones, laptops and other IoT devices. The power supply uses the ON Semi Quasi Resonant Flyback (QRF) PWM controller (NCP1342) with variable frequency control up to 300 kHz; Transphorm's TP65H300G4LSG (650 V, 240 mΩ GaN FET); and Weltrend’s WT6633P USB PD controller. This design enables high power density (~30 W/in3) and over 92.5 percent efficiency at 90 Vac.


  • USB-C PD 3.0
  • Power: 65W
  • Efficiency: greater than 92.5% @ 90 Vac
  • Input Voltage: Universal (90 Vac to 264 Vac)
  • Switching frequency (variable): up to 250kHz
  • Features TP65H300G4LSG
  • Features NCP1342
  • Easy-to-use platform to investigate GaN


  • Smart phones
  • Fast charging
  • Laptops and IoT


Typical Performance Curves

Output Power (W)

Output Power (W)

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