1 Introduction

Switching converters operating at over 400V are commonly used in electric vehicles, server power supplies, appliances, and communications equipment. Half-bridge based topologies require a gate driver IC that can be referenced to the switching node, which matches the bus voltage of the converter. Today, there are many options for gate drive ICs that can drive 400V, 800V, and even higher voltage FETs and IGBTs. Gate drive ICs can accomplish high blocking voltage with junction isolation which uses a built-in, high voltage FET to level-shift the low-voltage input signal to the high-voltage output. Alternatively, there are isolated gate drive ICs which use various methods to transmit an AC control signal while blocking DC voltages.

Before gate driver ICs which integrated high-voltage level-shifting or isolation existed, the only option for high-voltage gate drive was to build circuits with discrete elements. One common way to achieve high-voltage gate drive was to use a transformer in the gate drive loop (also called a gate drive transformer). Physically small transformers that can transfer a square wave of a PWM signal with minimal distortion were used. These transformers are called pulse transformers, and also see use in communications and other applications.

Level-shift gate driver ICs and isolated gate driver ICs have become very popular, and many applications which used to use gate drive transformers have switched to using half-bridge or isolated gate driver ICs. Despite the existence of these half-bridge or isolated gate driver ICs, there are still benefits to using a gate drive transformer in conjunction with non-isolated gate driver ICs that make people use them to this day.