65-W fast charger reference design delivers high efficiency and power density

Silanna Semiconductor has launched its RD-29 active clamp flyback (ACF)-based reference design that speeds the development of 65-W 1C fast chargers. The reference design is built around Silanna’s SZ1131 ACF controller and incorporates Transphorm’s Super GaN FET. The RD-29 is a production-ready 65-W 1C USB-PD fast charger reference design for travel adapters and battery chargers.

The 65-W fast charger reference design delivers peak efficiencies of 94.5% and flat efficiency across universal (90 – 265 Vac) input voltages and loads. No-load power is rated at 23 mW @ 230 Vac and the design measures 34.5 × 34 × 30.5 mm, translating into an uncased power density of 30 W/inch³.

The RD-29 incorporates everything a designer needs to develop a charger and exceeds conducted and radiated EMI requirements by more than 6 dB, according to Ahsan Zaman, director of product marketing at Silanna Semiconductor.

In addition, Zaman said the reference design provides 1% higher efficiency and reduces vampire power by as much as 44% when benchmarked against best-in-class commercially available 65-W charging products, and when combined with the SZ1131 ACF controller it enables compact, lightweight, and low power consumption 65-W chargers. It delivers <25-mW system-level no-load power consumption

The integrated SZ1131 ACF controller, in a 16-pin SOIC package, is the latest addition to Silanna Semiconductor’s family of CO2 Smart Power technologies that address power management challenges. The controller incorporates an adaptive digital PWM controller, an ultra-high-voltage (UHV) active clamp FET, active clamp gate driver, and startup regulator.

The ACF controller also uses Silanna’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, said the company.

The SZ1131 includes built-in protection against over-temperature, overvoltage, overcurrent, over-power, short circuit conditions and transformer core saturation faults without requiring additional external components.