How2 Get From AC To Below 1 V With eGaN FETs

Focus:

A common challenge in power management for the computing industry is how to most efficiently convert ac line voltage to the approximately 1.2 V dc consumed by high-performance digital processors and peripherals. Today, the most common approach is to first convert the ac line voltage to a 12-V dc power distribution bus in one isolated power stage, and subsequently convert 12 V dc down to about 1.2 V dc in a second, nonisolated stage. Multiplying the efficiencies of these two stages and adding the distribution losses typically results in a total system conversion efficiency of about 81%. This article examines options for improving this efficiency using the latest generation of enhancement-mode gallium nitride (eGaN) FETs from EPC. In doing so, it compares the efficiency of various distributed power schemes for converting ac power to 1.2 V dc using silicon MOSFETs and EGaN FETs in various combinations of intermediate bus voltages and switching frequencies. A similar analysis is done for converting ac power to 0.6 V dc. Naturally, the article points to advantages in using eGaN FETs both in terms of efficiency and converter size at the point of load.

What you’ll learn:

• How to improve overall power system efficiency when converting ac power to 1 V or less
• How to understand the efficiency tradeoffs in different power distribution schemes with different intermediate different bus voltages, switching frequencies, and MOSFET technologies

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Author & Publication:

Johan Strydom, Efficient Power Conversion, El Segundo, Calif., How2Power Today, Sep 27 2011

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