The reference design uses an open-loop flyback power supply to generate the 10-V isolated supply from the 3.3-V primary side supply. The steady-state peak primary current is less than 200 mA. Considering the reflected voltage and leakage voltage spikes, a MOSFET with voltage rating more than 20 V provides enough design margin. The MOSFET must support logic level gate voltage to enable gate drive from a 3.3-V line. The CSD17382F4 is used as the power switch for the open-loop flyback power supply to get a compact power supply. The CSD17382F4 device is a 30-V, 54-mΩ, N-Channel FemtoFET™ MOSFET technology and is designed and optimized to minimize the footprint in many handheld and mobile applications. This technology is capable of replacing standard small-signal MOSFETs while providing at least a 60% reduction in footprint size.