Maria Montero

Silanna Touts Efficiency and ease of design with the first controller …

At APEC this week, Silanna announced an Active Clamp Recovery (ACF) controller with integrated UHV components for AC / DC power adapters.

The power adapters used to charge our mobile devices have an increasing power demand as the devices consume more power. However, the power adapters themselves must remain small and cool at temperature, so the adapters have to negotiate conflicting demands.

One reason the small size is a challenge is the FET in the power adapters. The faster the switching frequency, the smaller the power adapter can be. However, faster switching leads to more leakage, and if that leak is stored, it can generate enough heat to burn the adapter.

What is Active Clamp Flyback?

Flyback controllers are often used to capture leaks and store it, but this is taken another step when the flyback controller is active.

Active clamp return is a method of harnessing the transformer leakage energy generated by the switching frequency. Active gripper return increases efficiency by intelligently sending stored leakage energy through the outlet in a controlled pattern later in the cycle. This allows the FET to shift to higher frequencies, reducing the required size of the power supply.

The SZ1101 tackles Active Clamp Flyback with integration

At APEC this week, AAC met with Zahid Rahim, vice president of marketing at Silanna Semiconductor, about the SZ1101. Silanna claims that the SZ1101 is the world’s first fully integrated active clamp return controller. In a typical AC-DC power supply, you have a flyback driver, but the active clamp flyback driver requires a few more components.

The front and rear of the SZ1101 PCB. Image courtesy of Silanna.

“In an active clamp flyback design, you need an active clamp MOSFET, a high voltage driver for that active clamp MOSFET, and you need a high voltage starting circuit. And then of course you need a fly back driver. “, Rahim states” So in the SZ1101, all four components are built into the IC. As a user, you get the benefit of active caliper kickback giving you greater efficiency. And you get the design simplicity of a feedback control. ” .

Scheme SZ1101. Image courtesy of Silanna.

The integration of the flyback with the three UHV components allows for a simpler setup that has many performance advantages. The platform is 93% efficient and built on a silicone design that gives it a low BOM. Furthermore, as an IC, the product has a lifetime reliability of millions of hours.

“With our solution, [designers] You can enjoy the benefits of active caliper kickback with the ease of a kickback driver design. That’s a disruption in the market, “says Rahim.

Silanna has a 30W product available now with a power density of 15W / in3, and will launch a 60W product next quarter.

Main features:

  • Integrated Ultra High Voltage Active Staple FET / Starter Voltage Controller / Regulator
  • Advanced adaptive digital controller
  • Tight regulation of the switching frequency for better utilization of the input EMI filter
  • Switching frequency up to 140 kHz
  • Cycle-by-cycle adaptive digital control (OptiMode)
  • Output power up to 30W.
  • Capable of more than 15W / in power density
  • 16-pin SOIC package

Key specs:

  • Input: 90 – 265 VAC
  • Output: 3.3V, 5V, 9V, 11V, 12V, 15V, 20V
  • Output current: 3A max.
  • Output Power: 30W Max
  • Output port: USB-PD 3.0 or PPS
  • Efficiency:> 93% total power efficiency with an all-silicone design

Featured image courtesy of Silanna.