New Industry Products

Transphorm and Silana Partner on GaN Adapter Reference Design

May 27, 2021 by Gary Elinoff

The resulting open frame, 65W USB-C PD charger unites Silana’s PWM controller with Transphorm’s SuperGaN FETs

The new solution is based on Silanna Semiconductor’s Active Clamp Flyback (ACF) PWM controller and Transphorm’s SuperGaN Gen IV platform. The combination yields a 65W USB-C power delivery (PD) charger with an efficiency peaking at 94.5% and an uncased power density of 30W per cubic inch.

Image courtesy of Transphorm
Image courtesy of Transphorm


Transphorm states that these performance levels outpace solutions based on silicon superjunction MOSFETs or e-mode GaN transistors, resulting in an ideal adapter design for powering laptops, tablets, smartphones and IoT devices. 


Transphorm’s SuperGaN FET 

The reference design’s TP65H300G4LSG is a 650-volt device with a 240 mΩ RDS(ON) in a PQFN88 package. Built using Transphorm’s Gen IV platform, it employs epi technology which requires no external protective circuitry as do e-mode devices. The result is greater efficiency and power density along with a smaller BOM


Silanna Semiconductor’s ACF PWM Controller

Silanna Semiconductor’s SZ1130 Active Clamp Flyback Controller integrates 

  • An adaptive digital PWM controller
  • An active Clamp FET
  • An active clamp gate driver
  • An UHV startup regulator


While paired with the Transphorm SuperGaN FET in this application, the device is touted as being “technology-agnostic” with wide areas of application. And, as is the case with its partner device, it’s high level of internal integration leads to a smaller number of ancillary components and faster time to market for OEMs.


The Reference Design

Formally denoted as the TDADP-SIL-USBC-65W-RD, the reference design is described in detail in its design guide.

The Evaluation Board, topside view. Image courtesy of the TDADP-SIL-USBC-65W-RD overview
The Evaluation Board, topside view. Image courtesy of the TDADP-SIL-USBC-65W-RD overview


The completed design is powered via an input range of 90 to 265 VAC. Programmable outputs are 5, 9 or 15 VDC at 3 amps or 20 VDC at 3.25 amps. The device can switch at up to 140 kHz and features tight switching frequency regulation for improved input EMI filter utilization. It incorporates OptiMode cycle-by-cycle adaptive digital control and Multi-Mode operation including burst mode, quasi-resonant and valley mode switching. 

The unit’s no-load power consumption is spec’d at 57.6 mW and 66.1 mW with power inputs of 115 VAC and 230 VAC, respectively.

Built-in protections include:

  • Over-temperature (OTP)
  • Under-voltage lockout (UVLO)
  • Over-voltage lockout (OVLO)
  • Peak current limitation (PCL)
  • Overpower protection (OPP)
  • Current oscillation protection (OSC)


Silanna’s and Transphorm’s Other Collaborations

Both companies realize the utility of combining forces with others when it can effectively advance the state of the art. We recently covered a combined effort between Transphorm and Keysight which yielded a reference design for a high-speed, low emi switched mode power supply (SMPS). Silana also partnered with GaN Systems to create a previous reference design for another 65 watt active clamp flyback charger, perhaps underscoring the “technology-agnostic” nature of the SZ1130.


How the Technologies of Transphorm and Silanna Technologies Reinforce Each Other

As stated by Tushar Dhayagude, Vice President Field Applications and Technical Sales, Transphorm, “Transphorm and Silanna Semiconductor offer best-in-class performance in a complete GaN-based reference solution for USB-C PD adapter customers by pairing our SuperGaN devices with Silanna Semiconductor’s novel and highly integrated active clamp flyback controller.” He goes on to state that “Our GaN FETs are known to improve efficiency, power dissipation and size of AC/DC chargers, particularly when compared to competitive e-mode GaN and integrated GaN IC solutions. Our partnership is a powerful combination of two innovators that will positively impact the adoption of GaN in power adapters worldwide.” 

In the view of Ahsan Zaman, Director of Marketing, Silanna Semiconductor,  “Our ACF controllers are versatile and provide the design flexibility for the charger manufacturers to select their preferred FET technology. The ACF controller is delivering 94.5 percent efficiency with the combination of our SZ1130 and Transphorm’s TP65H300G4LSG, achieving industry-leading performance.”