Leveraging Special Dead-Time Control Modes To Optimize GaN-Based Buck Converter Designs

Focus:

This article explores the switching dynamics at play when GaN FETs are used in place of silicon MOSFETs for the power stage in synchronous buck converters and how specialized dead-time adjustment modes in two buck controllers—the LTC7891 and LTC7890—can be used to optimize dead time based on design goals for efficiency and reliability. The article begins by discussing differences in silicon MOSFET and GaN FET structures and how they affect reverse recovery and associated losses, reverse conduction losses, and deadtime requirements for GaN. The specialized deadtime adjustment modes in the LTC7891 and LTC7890 are explained. The article then discusses probing and layout requirements for verifying deadtime performance, considerations in selecting gate resistance, and selection and usage of the three specialized deadtime adjustment modes.

What you’ll learn:

• How to understand the differences in deadtime requirements for GaN FETs versus silicon MOSFETs
• How to measure GaN FET switching waveforms
• How to apply specialized deadtime control modes in the LTC7891 and LTC7890 synchronous buck controllers

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Author & Publication:

James R. Staley, Analog Devices, Durham, N.C., How2Power Today, Sep 15 2025

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