Silanna claims first fully integrated ACF controller

By Carolyn Mathas, contributing writer

Meeting the power-hungry and fast-charging demands of mobile devices is an ongoing challenge, especially when trying to design an ever-smaller form factor that remains cool to the touch. Silanna Semiconductor addresses those challenges with its SZ1101 flyback PWM controller  for high-power-density AC/DC power adapters. The all-silicon controller combines four ACF components: an advanced ACF controller and three ultra-high-voltage components — an active clamp FET, an active clamp driver, and a startup voltage regulator.

The SZ1101 delivers over 93% efficiency at 9 V/3 A and over 15-W/in.³ power density at 30 W while using an industry-standard MOSFET main switch.

The SZ1101 offers the design simplicity of a traditional flyback controller with the benefits of an ACF controller, said Silanna. The SZ1101 integration enables designers to easily create efficient, high-power-density adapters with low bill-of-material (BOM) cost. It eliminates the need for a tight tolerance for the clamp capacitor and leakage inductance. The ACF controller incorporates Silanna’s proprietary OptiMode advanced adaptive digital control to precisely manage critical on/off timing of the active clamp FET based on system operating conditions.

The SZ1101 reduces BOM cost through integration and the use of a lower-cost transformer, SR FET, clamp capacitor, and input filter.

The SZ1101 delivers lossless recycling of leakage energy to the output and near-zero-voltage switching (ZVS) for further efficiency improvements. Additional features include optimal valley mode switching, tight switching frequency control, and intelligent switching frequency handling, all of which result in higher efficiency, a reduced main switch voltage rating, and appreciable attenuation of common-mode EMI noise.

Suited for such applications as mobile phones, tablets, notebooks, video game consoles, and other handheld devices, the SZ1101-based power supplies adhere to stringent DoE and EU CoC efficiency and no-load standby power requirements.

A latched version (SZ1101-01) in an industry-standard 16-pin SOIC package is currently available for sampling, and a hiccup-mode version is targeted for Q2. For information on the ACF controller, visit SZ1101 , and for information on a 30-W USB-PD Evaluation Board using SZ1101, click here .