MOSFET Failure Protection for Single Output PolyPhase® Converter

The low output voltage rails in many of today’s leading edge communication, networking, computer and industrial systems must be designed to meet the competing demands of higher load current, higher efficiency and diminishing amounts of board real estate. For cases where the load current is high, the most effective approach is to tie two or more phases together. This poses a design challenge for high-end systems which require 100% uptime or which use high cost processors: how to protect the load and to ensure the output continues to regulate if a DrMOS or MOSFET failure occurs. In this video, we will show how the LTC3774 controller can be used in conjunction with Hot Swap circuits and ideal diode circuits to meet this challenge. The LTC3774 itself is a dual output buck controller designed to interface with DrMOS devices and utilizes a proprietary current sensing technique, which allows stable operation with submilliohm DCR sensing. It provides an output voltage of 0.6V to 3.5V with an accuracy of ±0.75%, an input voltage range of 4.5V to 38V and a switching frequency range of 200kHz to 1.2MHz.