SNVSBY7 March 2021 TPS92390
Gate-drive voltage for the FET is 5V. Switching FET is a critical component for determining power efficiency of the boost converter. Several aspects need to be considered when selecting switching FET such as voltage and current rating, RDSON, power dissipation, thermal resistance and rise/fall times. An N type MOSFET with at least 25% higher voltage rating than maximum output voltage must be used. Current rating of switching FET should be same or higher than inductor rating. RDSON must be as low as possible, less than 20 mΩ is recommended. Thermal resistance (RθJA) must also be low to dissipate heat from power loss on switching FET. In most cases, a resistance is recommended between GD pin and Switching FET's gate terminal. It could be used to control the rising/falling time of the switching FET. This gate resistance could offer the flexibility of balancing between EMC performance and efficiency.