Vipergan50 is the first product of Italian French semiconductor viperplus series that can provide up to 50W power under wide operating voltage (9 V to 23 V). This is also ST’s first Viper device using gallium nitride (GAN) transistors. Thanks to the 650 V Gan device, the standby power consumption of vipergan50 is less than 30 MW when the adaptive burst mode is on. In addition, the protection function of the device can improve robustness and help reduce the materials used. Qfn5x6 mm package also makes it one of the smallest devices in the same power output in the industry. Vipergan50 has been supplied in batch, and the development board with usb-pd power supply port will be available soon.

Why choose QR ZVS flyback converter?

The power density of the charger is getting smaller and smaller. Engineers often use quasi resonant (QR) zero voltage switching (ZVS), also known as bottom opening, in switching power supplies (SMPS) for televisions and other electrical appliances. This topology is emerging in more products. The reason is that the power density becomes higher and higher every ten years. For example, today’s TV has higher pixels and stricter power consumption requirements. Similarly, although 50W charger is not a new product, consumers need products with smaller appearance and can quickly charge laptops, tablets, mobile phones and other devices.

Smaller and smaller chargers

QR ZVS flyback converter constantly pursues higher efficiency. Quasi resonant converter is often used in the industry, mainly because of its high efficiency. The traditional PWM converter turns on the device at the highest voltage, which will cause the power loss to increase with the increase of switching frequency. Engineers can use buffer circuits to alleviate this situation, but the best way to improve efficiency is soft switching, which means switching when the voltage or current is zero. For this purpose, the square wave signal is converted into a sinusoidal waveform by resonance (inductance capacitance or LC). In ZVS, start-up occurs at the bottom of the curve or valley. Over the years, engineers have tried to improve the efficiency of QR ZVS flyback converter, and Gan just gives a new answer.

What are the unique advantages of vipergan50?

Advanced Gan transistor characteristics. The vipergan50 uses the same 650 V Gan transistor as the mastergan series, so it has similar advantages. For example, the high electron mobility of Gan means that the device can be suitable for high switching frequencies. Therefore, the device can withstand greater load and reduce loss at the same time. In view of this, Gan can be used to manufacture power supplies that can output higher power and have a smaller overall size. The vian50 is the first semiconductor product in this category, so it has great symbolic significance. STMicroelectronics will continue to focus on GaN and use transistors with higher specifications. Therefore, future vipergan models will have higher output power.


Multi mode operation the vipergan50 has a variety of different working modes, and its switching frequency can be adjusted according to its load to maximize the power efficiency under all input voltage and load conditions. Under high load, quasi resonant (QR) mode combined with zero voltage switch can minimize conduction loss and electromagnetic radiation (EMI). Under light load, the bottom jump mode can control the switching loss and prevent the noise that can be heard by human ears by using the proprietary bottom locking technology of Italian French semiconductor. Frequency turn back mode combined with zero voltage switch can ensure as high energy efficiency as possible under light load conditions. Adaptive intermittent operation mode can minimize power loss under very low load conditions. In addition, the advanced power management function can reduce the standby power to less than 30MW.

Various operating modes of vipergan50

Better protection function. The built-in function of vipergan50 ensures the safety and reliability of power supply, including output overvoltage protection, brown in / brown out, and input overvoltage protection. Input voltage feedforward compensation is also provided to minimize output peak power changes. Other safety features include embedded over temperature protection and frequency jitter to minimize EMI. Therefore, the designer can reduce the components required on the circuit board, so as to reduce the materials used.

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