Abstract

In solar optimizer applications, Buck topology is frequently used in power stage of the whole system. Consequently, to drive the FETs inside Buck circuit, half-bridge gate driver is an easy way. But in solar optimizer or some other applications, the high side FET is often required to operate with 100% duty cycle. The common half-bridge gate driver with bootstrap diode and capacitor is unable to achieve 100% duty cycle for high side FET. Initially, this application note covers the background of why high side FET can operate with 100% duty cycle in optimizer. A design to achieve 100% duty-cycle using half-bridge gate driver is introduced subsequently. Also, risks that can arise in the design are analyzed by theory and simulation. Based on the theory and simulation, comparative experiments are also completed for verification. Design consideration and suggestions to avoid these risks are introduced in the end of the publication.