Flyback controllers drive GaN HEMTs directly to produce high power density

Nexperia has introduced a series of ac-dc power controllers which enable implementation of power-dense, gallium nitride (GaN)-based flyback converter circuits for use in USB Power Delivery (PD) devices, and other applications that require high power density. 

The new NEX806xx and NEX808xx series are quasi-resonant/multi-mode flyback controllers which operate from a wide supply-voltage range of 10 to 83 V, making them suitable for use in applications that have a wide output-voltage range, such as USB PD power supplies. 

The new NEX81801 and NEX81802 are adaptive synchronous rectifier controllers. In combination with USB PD controllers such as the Nexperia NEX52xxx series, and with other discrete power devices, these controllers can be used to implement a flyback converter which optimizes the current-sense voltage level and pulse-frequency modulation mode, reduces standby power, and achieves high efficiency across the entire load range. 

The primary-side power controller can be used to drive a silicon MOSFET or GaN high electron mobility transistor (HEMT) directly, eliminating the need for a discrete gate driver. 

An adaptive turn-on detection circuit in the NEX81801 and NEX81802 can prevent the synchronous rectification circuit from being mistakenly turned on when the drain-source voltage crosses zero in discontinuous conduction mode, and under certain load conditions. This detection circuit also enhances conduction efficiency in light-load conditions.