ACF controller delivers high functionality

Silanna Semiconductor has extended its CO₂ Smart Power Family of AC/DC and DC/DC converter technologies with the launch of a highly integrated active clamp flyback (ACF) controller. The new SZ1200 ACF controller integrates adaptive digital PWM control with ultra-high-voltage (UHV) components, comprised of a 700-V primary GaN FET, X capacitor (X-Cap) discharge circuit, active clamp driver and startup regulator, in a single 8 × 7-mm QFN package.

(Source: Silanna Semiconductor)

Silanna’s CO₂ Smart Power technologies are designed to help manufacturers simplify design, improve performance and meet environmental sustainability goals. The SZ1200 integrated ACF controller combines the ease of design of a simple flyback controller, while providing the benefits of ACF, Silanna said.

These benefits include recycling of the leakage inductance energy of the flyback transformer and limiting primary FET drain voltage spikes during turn-off events. Target applications include high-efficiency and high-power-density power supplies, USB-PD/QC AC/DC power adapters and battery charging applications.

The SZ1200 leverages Silanna’s OptiMode digital control architecture, which adjusts operation mode on a cycle-by-cycle basis to maintain high efficiency, low EMI, fast dynamic load regulation and other key power supply parameters such as line voltage and load vary. The device, delivering above 93% efficiency at low line, provides consistent efficiency across the universal input voltage range (90 – 265 VAC) and various loading conditions of up to 150-W single-port and multi-port USB-PD applications, the company said.

The SZ1200 allows designers to program switching frequency up to 250 kHz, supporting high power densities. Switching frequency is confined within a tight frequency band to simplify EMI filtering, Silanna said.

Additional efficiency and EMI performance improvements are thanks to the adaptive digital control of the active clamp operation, which enables near ZVS turn-on of the primary FET and clamps the drain voltage during the turn-off, the company said.

Other features include  continuous conduction mode (CCM) operation, very low system no-load power consumption, QR valley mode switching, regulated burst-mode and self-tuning valley detection. Protection features include OTP, OVP, OCP, OPP and OSCP.

Engineering samples are expected in April 2024 with full production planned at the end of the second quarter of 2024. Reference designs are available. Silanna is showcasing its full portfolio of AC/DC and DC/DC products at APEC 2024. The company also is hosting a presentation on Cutting-Edge Power Sharing Technology.