The DC-DC converter regulates the direct current (DC) voltage based on the duty cycle set by the PWM signal. The type of DC-DC converter to reduce DC voltage is a step down/buck converter. For fast switching applications, a DC-DC converter with high efficiency is needed. Synchronous buck converter is a buck converter topology that uses two MOSFET switches which allows good efficiency values. This research will analyze the selection of MOSFET components which is the main factor that influences the efficiency of a synchronous buck converter. The MOSFET variations used in research are IPB107N20N3, IRF250N, AOD4504. Simulation of the converter circuit for MOSFET variations was carried out in the LTspice program. The highest efficiency value obtained from the converter circuit simulation was 98.2872% using a MOSFET type IPB107N20N3 with trend towards duty cycle between 92%-98%. The inductor and capacitor ripple values of the converter are 980 mA and 1.62 V respectively for all MOSFET variations. © 2024 IEEE.