Silanna Semiconductor’s ACF-Based, GaN Reference Design Sets New Benchmark

Silanna Semiconductor, has launched a new Active Clamp Flyback (ACF)-based reference design that will simplify and speed the development of 65W 1C fast charger applications.
Built around Silanna’s SZ1131 ACF controller and incorporating Transphorm’s Super GaN FET, the RD-29 is a production-ready 65W 1C USB-PD reference design for travel adapters and battery chargers. The reference design delivers industry-leading peak efficiencies of 94.5% and flat efficiency across universal (90 – 265Vac) input voltages and loads. No-load power is just 23mW @ 230Vac and the design measures only 34.5mm x 34mm x 30.5mm, giving it an uncased power density of 30W/inch3.

“The RD-29 is a production-ready design that incorporates everything a designer needs to develop a charger and that already exceeds conducted and radiated EMI requirements by more than 6 dB,” says Ahsan Zaman, director of product marketing at Silanna Semiconductor. “Benchmarked against the best-in-class commercially available 65W charging products this reference design provides an impressive 1% higher efficiency and reduces vampire power by as much as 44%. Combined with the industry-leading integration of our SZ1131 ACF controller, this has allowed us to create a solution that engineers can use to quickly develop compact and lightweight 65W chargers that operate with the least possible power consumption.”
Supplied in a 16-pin SOIC package, the SZ1131 ACF controller is the latest addition to Silanna Semiconductor’s family of CO2 Smart Power technologies. These technologies address the ultimate power management challenge facing engineers by simplifying design and improving performance while addressing environmental sustainability goals through more efficient energy use.
The SZ1131 incorporates an adaptive digital PWM controller, ultra-high-voltage (UHV) active clamp FET, active clamp gate driver and startup regulator and employs Silanna Semiconductor’s OptiMode digital control architecture. This 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 in response to varying line voltage and load. The SZ1131 incorporates protection against over-temperature, over-voltage, over-current, over-power, short circuit conditions and transformer core saturation faults without the need for additional external components.
RD-29 Key Features

65W 1C high-power-density (30W/inch3 uncased) reference design
5% peak efficiency
< 25mW system-level no-load power consumption
> 6dB conducted and radiated EMI margins
Flat efficiency across universal (90 – 265Vac) input voltage and load
Uses Silanna Semiconductor’s newest fully integrated ACF controller (SZ1131)

SZ1131 integrates ACF controller with UHV active clamp FET, active clamp driver, and start-up regulator
Up to 146kHz switching frequency operation
Ultra-low no-load power consumption
OptiMode™ cycle-by-cycle adaptive digital control
Self-tuning valley mode switching (VMS)
Multi-mode operation (burst mode, QR, VMS)
OTP, OVP, OCP, OPP, and Output Short Circuit Protections

CO2 Smart Power by Silanna Semiconductor