Gone are the days where power supplies use simple pulse-width modulators (PWMs) with limited bells and whistles. Integrated circuits (ICs) have dozens of pins and features like soft start, current limiting, pre-bias startup, and boot capacitors. But what do some of these features mean, and which ones are preventing your power supply from working? This article provides a logical debug process for a malfunctioning design. The troubleshooting process starts with the simple “gotchas” and then tackles more difficult areas that even the experienced designer may find helpful.