Silanna Semiconductor expands converter line with launch of active clamp flyback controller

Silanna Semiconductor has expanded its CO2 Smart Power Family of AC/DC and DC/DC converter technologies with the launch of an active clamp flyback (ACF) controller that integrates adaptive digital PWM control with ultra-high-voltage (UHV) components comprising a 700 V primary GaN FET, X capacitor (X-Cap) discharge circuit, active clamp driver and start-up regulator.

Silanna’s CO2 Smart Power technologies help engineers by simplifying design and improving performance while addressing environmental sustainability goals through more efficient energy use. Well-suited for high-efficiency and high-power-density power supplies, USB-PD/QC AC/DC power adapters, and battery charging applications, the new SZ1200 integrated ACF controller combines the ease of design of a simple flyback controller with all the benefits of ACF. These include recycling the leakage inductance energy of the flyback transformer and limiting primary FET drain voltage spikes during turn-off events.

Delivering above 93% efficiency at the low line, the SZ1200 offers consistent efficiency across the universal input voltage range (90 – 265 Vac) and various loading conditions of up to 150W single-port and multi-port USB-PD applications. Silanna’s OptiMode digital control architecture 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 as line voltage and load vary. Very low no-load power consumption for the most stringent USB-PD applications further minimizes energy use during system stand-by.

By allowing designers to program switching frequency to up to 250 kHz, the new controller supports high power densities while advanced digital active clamp operation ensures best-in-class efficiency. Switching frequency is confined within a tight frequency band to simplify EMI filtering. Further efficiency and EMI performance benefits are realized through 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.

SZ1200 also incorporates continuous conduction mode (CCM) operation, which allows delivering up to 225% rated output power for a limited duration without sacrificing the power density. This feature is targeted for applications requiring peak power, such as laptop and notebook power adapters.

SZ1200 Key Features include: High-frequency ‘CO2 Smart Power’ ACF controller; Configurable high-switching-frequency operation (up to 250 kHz); Integrated 700 V GaN primary FET; Integrated UHV X-cap discharge circuit, active clamp driver, and start-up regulator; Over 93% efficiency at the low line; Flat efficiency across universal input voltage (90 – 265 Vac) and loading conditions; CCM for increased peak power delivery and better utilization of transformer core in universal input applications; QR valley mode switching and boosting for low EMI and near-ZVS operation; OptiMode cycle-by-cycle adaptive digital control; Regulated burst-mode; Self-tuning valley detection; OTP, OVP, OCP, OPP, and OSCP among various other protections; Very low system no-load power consumption; Space-saving 37-pin 8 mm X 7 mm QFN Package;

Target engineering sample release date is April 2024 with full production planned for the end of Q2, 2024.