This paper introduces a two-stage high step-down dc-dc converter for datacenter power distribution. The proposed converter can be implemented on the server motherboards and supply CPUs and GPUs directly from the 48V bus. The ISOP (input-series output-parallel) architecture of the converter reduces voltage and current stresses for semiconductor devices. The converter is comprised of two modules with lower voltage levels. A two-stage architecture realizes each module. An LLC converter decreases input voltage. The modulation scheme of the LLC converter is modified using a frequency multiplier technique. Changing inverter gain contributes to voltage step-down, thus reducing transformer turns ratio and associated losses. A multiphase buck converter provides point-of-load regulation. Since the LLC converter decreases voltage significantly, the buck converters can be operated at a higher duty. A 48V-0.8V 200A sample converter is considered to assess the capability of the proposed converter. Its voltage regulation and soft switching capabilities are tested using MATLAB/Simulink. A Modular Two-Stage High Step-Down DC-DC Converter Using Frequency Multiplier Circuit for Datacenter Applications