Recent advancements in liquid metal heat dissipation technology include utilizing an electromagnetic pump to induce a Lorentz force, enhancing liquid metal flow and heat dissipation. This paper introduces a full-bridge DC-DC converter for driving the electromagnetic pump. To optimize energy efficiency, particular attention is given to the analysis of output impedance and the design of a planar transformer with a minimized equivalent series impedance. Comprehensive simulations and experiments are conducted to validate the system’s performance. A 5 V input voltage 2.5~13.75 mV output voltage FB DC-DC converter with 0.25 mΩ load resistance is demonstrated. The maximum conversion ratio is 2000.