By Alex Lidow, CEO, Efficient Power Conversion,
Alejandro Pozo, Director of Applications Engineering, Efficient Power Conversion,
Ionel “Dan” Jitaru, CEO, Rompower Energy Systems

The industry shift toward 800 V_DC power distribution for AI server racks requires novel DC-DC converter architectures to optimize delivery. Because of its superior efficiency and power density, the Input-Series-Output-Parallel (ISOP) topology is rapidly becoming the standard. This paper analyzes three 800 V-input ISOP converters tailored for 50 V, 12 V, and 6 V nominal output rails. Implementing gallium nitride (GaN) transistors on both the primary and secondary switching sides enables these converters to establish new performance benchmarks for peak and full-load efficiency at each critical voltage node.

The ISOP topology is ideally suited for converting high voltages such as 800 V to much lower voltages due to its multi-stage architecture that enables the use of lower voltage transistors, in this case GaN transistors, switching at higher frequencies with lower overall switching losses and conduction losses than more conventional topologies that require higher voltage devices switching at lower frequencies. Figure 1 is a block diagram showing an ISOP converter with eight stages. Each stage is an LLC converter with an input voltage of 100 V and an output voltage of 12.5 V.

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Maurizio Di Paolo Emilio, Director of Global Marketing Communications at EPC