How low-voltage GaN FETs enable multi-kW, 800 V isolated converters

# Overview

This brief explains how low-voltage gallium nitride (GaN) field-effect transistors (FETs) are being applied in multi-kilowatt, 800 V isolated converters using Efficient Power Conversion (EPC)'s ISOP multi-stage architecture. The approach aims to meet the high-power, high-efficiency needs of AI data centers while reducing output ripple and bulk capacitance.

# Why this matters

# What EPC's ISOP architecture does

The ISOP (isolated stage(s) of power) architecture breaks the 800 V conversion into multiple isolated stages. Each stage uses low-voltage GaN FETs rather than a single high-voltage device. Putting low-voltage devices in series across stages gives these benefits:

• Lower per-device voltage stress, so designers can exploit the high-speed, low-on-resistance properties of low-voltage GaN.
• Reduced requirement for large output capacitance because multi-stage control and isolation lower output ripple at the converter output.

# Practical effects for data-center power chains

For facility and rack designers, the ISOP approach addresses common constraints:

• Efficiency: Higher peak efficiency (reported 98.5%) reduces thermal load and operating cost.
• Size and cost: Lower output capacitance requirement can shrink bulk capacitor banks and associated board area and cost.
• Ripple and power quality: Reduced output ripple simplifies downstream regulation and improves voltage headroom for server power supplies.

# Trade-offs and considerations

Using multiple isolated stages introduces complexity in control, isolation components, and staging. Designers must balance the added topology and isolation hardware against the benefits in device performance, lower capacitance, and overall efficiency. The architecture is most compelling when system-level gains—in energy, thermal management, or board-level space—outweigh the additional design and component complexity.

# Bottom line