New Industry Products

Silanna Semiconductor’s Newest Fully Integrated Active Flyback Controllers Offer High-Efficiency Design

April 15, 2020 by Shannon Cuthrell

Silanna’s expanded portfolio of active clamp flyback controllers focuses on high power density and low BoM costs.

Silanna Semiconductor introduced its expanded portfolio of Active Clamp Flyback (ACF) controllers this week. The new SZ110 and SZ1130 active clamp flyback PWM controllers integrate an adaptive digital PWM controller and ultra-high-voltage components such as an active clamp FET, an active clamp gate driver, and a startup regulator.


Image courtesy of Silanna Semiconductor. 


The all-silicon design produces over 94% efficiency and 27 W/in3 power density at 65W for AC/DC power adapters.

The company’s flagship line of ACF controllers is engineered for mobile phone travel adapters and compact adapters for notebooks, video game consoles, and wall chargers. 

“Unlike conventional ACF designs, tight tolerances of the clamp capacitor and leakage inductance values are not required for proper operation of the circuit in high volume production,” said Silanna Semiconductor Director of Marketing Ahsan Zaman in a news release. 

Utilizing Silanna’s OptiMode digital control architecture, the SZ110 and SZ1130 adjust the devices’ operation each cycle to maintain high-efficiency, low EMI, and fast dynamic load regulation. The SZ1110 is designed for up to 33W and the SZ1130 is designed for up to 65W output power, including USB-PD and Quick Charge applications, according to Zaman. 

Because the devices use an ACF design, it recycles the leakage inductance energy of the flyback transformer and limits the primary FET drain voltage spike during turn-off events. 


Flyback Controllers and ACF Controllers

An average flyback controller is a common switching-regulator topology. And a flyback controller is an integrated circuit that allows for a designer to implement a flyback converter by incorporating other external components. 

Active clamp flyback controllers utilize a FET and capacitor in the converter’s clamp circuit. The active clamp reduces power loss and increases efficiency through power storage. An active clamp flyback controller has the ability to use a higher switching frequency, leading to a smaller solution size. 


Device Features

  • Integrated UHV Active Clamp FET, Active Clamp Driver, and Start-up Regulator
  • Capable of Over 94% Efficiency
  • Flat Efficiency Across Universal (90 - 265 Vac) Input Voltage and Load
  • Up to 146 kHz Switching Frequency Operation
  • OptiMode™ Cycle-by-Cycle Adaptive Digital Control
  • Self-Tuning Valley Mode Switching (VMS)
  • Multi-Mode Operation (Burst Mode, QR, VMS)
  • > 6dB EMI Margin
  • OTP, OVP, OCP, OPP, and Output Short Circuit Protections
  • <50 mW No Load Power Consumption
  • Up to 65 W Output Power
  • 16-pin SOIC Package


Device Applications 

  • High Power Density AC/DC Power Supplies
  • High-Efficiency Power Adapters
  • USB-PD/QC AC/DC Power Adapters
  • Battery Chargers for Mobile Devices


Image courtesy of Silanna Semiconductor. 


Silanna’s Growing Family of ACF Products

The San Diego-based company first launched this product family with the SZ1101 at the Applied Power Electronics Conference in 2019. Silanna claimed that the ACF controller with integrated UHV components for AC/DC power adapters to be the “world’s first fully-integrated” ACF controller. 

“Less than a year ago we launched the SZ1101, the world’s first Active Clamp Flyback Controller, to an incredible customer and industry response,” said Mark Drucker, CEO of Silanna Semiconductor, in a news release

While Silanna Semiconductor didn’t get the opportunity to present its products at this year’s APEC event, which was canceled over COVID-19 concerns, it kicked off the year announcing the production of its 33W SZ1101 and 65W SZ1105 integrated ACF controllers. 


Advancing Mobile Technologies 

Drucker says one of the bigger questions surrounding mobile technologies, especially for Silanna Semiconductor, is how to deal with devices being drained of battery power faster and faster over time. 

“This month is a really good example of this. As we become more dependent on our devices and we're streaming more and more video — battery life is going to continue to be an issue,” Drucker said. “You have to be able to deliver more power.”

In order to deliver that power, Drucker said the main options are to design a larger adapter or configure more power into a smaller footprint. The latter, he said is always most optimal. 

“That, in essence, is really what we're all about in everything we do. And that requires higher efficiency, ultimately driving the higher switching frequency,” Drucker said. “That’s certainly something we’re delivering today.”

To view a demonstration of the ACF controllers, visit Silanna’s online demo room.