“Due to the lack of body diode in hard-switching applications, GaN-based topologies may incur higher power losses due to the larger effective body diode voltage of GaN devices,” according to the company, which explained: “GaN transistor reverse conduction voltage is dependent on the threshold voltage and the off-state gate bias. The threshold voltage of a GaN transistor is typically higher than the turn-on voltage of a silicon diode, leading to a disadvantage during third quadrant operation. This gets worse with long controller dead-times.”
If the transistor has an active partner to take over reverse-conduction, then reducing dead-time, when the transistor has to reverse-conduct, will help maintain efficiency, pointed out Infineon, and so can connecting a Schottky diode in anti-parallel with the GaN transistor.
And it is this second approach the new device has been designed for.
Sadly, the only extra information that the company is releasing at the time of writing is that it will be a 1.5mΩ transistor in 3 x 5mm PQFN package. Even the part number appears to be confidential – Electronics Weekly has requested its other characteristics including reverse voltage and reverse recovery charge.
Use is expected in intermediate bus converters, synchronous rectifiers in USB-C chargers and motor drives.
