GaN transistors add Schottky diodes to boost converter efficiency

Infineon Technologies AG has introduced the world’s first gallium nitride (GaN) power transistors with integrated Schottky diode for industrial use. The product family of medium-voltage CoolGaN Transistors G5 with integrated Schottky diode increases the performance of power systems by reducing undesired deadtime losses, thereby further increasing overall system efficiency. Additionally, the integrated solution simplifies the power stage design and reduces BOM cost.

In hard-switching applications, GaN-based topologies may incur higher power losses due to the larger effective body diode voltage (V _SD) of GaN devices. This gets worse with long controller dead-times, resulting in lower efficiency than targeted. Until now, power design engineers often required an external Schottky diode in parallel with the GaN transistor or tried to reduce dead-times via their controllers. All of which is extra effort, time, and cost. The new CoolGaN Transistor G5 from Infineon significantly reduces these challenges by offering a GaN transistor with an integrated Schottky diode appropriate for use in server and telecom IBCs, DC-DC converters, synchronous rectifiers for USB-C battery chargers, high-power PSUs, and motor drives.

GaN transistor reverse conduction voltage (V _RC) is dependent on the threshold voltage (V _TH) and the OFF-state gate bias (V _GS) due to the lack of a body diode. Moreover, the V _TH of a GaN transistor is typically higher than the turn-on voltage of a silicon diode, leading to a disadvantage during the reverse conduction operation, also known as the third quadrant. Hence, with this new CoolGaN Transistor, reverse conduction losses are lower, compatibility with a wider range of high-side gate drivers, and with deadtime relaxed, there is broader controller compatibility resulting in a simpler design.

The first of several GaN transistors with integrated Schottky diode is the 100 V 1.5 mΩ transistor in a 3 x 5 mm PQFN package.

Engineering samples and target datasheet are available upon request.