Characterization of Cdv/dt induced power loss in synchronous buck DC-DC converters

Good understanding of power loss in a high frequency synchronous buck converter is important for design optimization of both power MOSFET and circuit itself. Most of the MOSFET power losses are relatively easy to quantify. The exception is the power loss associated with Cdv/dt induced turn on of the low-side MOSFET (synchronous rectifier). This paper characterizes the Cdv/dt induced power loss in two ways. First, detailed device characterization, in-circuit testing, and modeling are used for a comparative loss calculation. This method requires specialized test equipment and is rather complicated and time consuming. A simple method is then introduced to very accurately quantify the Cdv/dt loss. With this method, the Cdv/dt induced power loss on synchronous buck converters at different operation conditions can be readily assessed. The impacts of Cdv/dt induced turn on different applications are addressed.