ACF Controller for power adapters up to 100W

Silanna Semiconductor has launched an integrated active clamp flyback (ACF) controller that will reduce the operational and no-load/ stand-by power consumption of high-efficiency chargers and adapters.

The SZ1131 ACF controller is the latest addition to Silanna’s family of CO2 Smart Power technologies which have been developed to simplify the design and improve the performance ofpower management, while helping to address the environmental sustainability goals through more efficient energy use.

In the case of the SZ1131, efficiencies of up to 95% across universal (90Vac – 265Vac) input voltages and varying loads, combined with ultra-low no-load power of less than 20mW (including USB-PD applications) significantly reduce overall energy consumption.

The ACF controller is targeted at high efficiency and high power density adapters of up to 65W output power with universal input and 100W output power with PFC-support applications, including single-port and multi-port USB-PD fast chargers.

The SZ1131 incorporates an adaptive digital PWM controller, ultra high-voltage (UHV) active clamp FET, active clamp gate driver and startup regulator.

The SZ1131 also provides the ease-of-design of a simple flyback controller with all the benefits of an ACF design, including recycling the leakage inductance energy of the flyback transformer and limiting the primary FET drain voltage spike during the turn-off events.

Employing Silanna’s OptiMode digital control architecture, the SZ1131 is able to adjust the device’s mode of operation on a cycle-by-cycle basis to maintain high efficiency, low EMI, fast dynamic load regulation, and other key power supply parameters in response to varying line voltage and load.

An all-silicon 65W USB-PD reference design using the SZ1131 demonstrates a 30W/inch3 power density (uncased) with ~93% low line (90Vac) and > 94% high line (230Vac) efficiencies, while using lower cost components. These include a conventional RM8 transformer, 100V SR FET, minimal clamp capacitor, and a single common mode choke in the input filter.

Supplied in a 16-pin SOIC package, the SZ1131 offers protection against over-temperature, over-voltage, over-current, over-power and short circuit conditions, and transformer core saturation faults without the need for additional external components.