Part Number:TPS54335A
Tool/software: WEBENCH® Design Tools
It seems that Webench won't run operating values on DCM, at least not on this part. It switches to forced constant conduction mode, i.e. anti-green mode where the inductor is charged and discharged by the IC. The part does claim that it's got low-load efficiency mode and this appears counterintuitive. If the controller uses FCCM to maintain tight control over output at all situations, how can it be saving energy at the same time?
The datasheet is a bit strangely worded here:
7.3.2 Light-Load Operation
The device monitors the peak switch current of the high-side MOSFET. When the peak switch current is lower
than 0.5 A (typical), the device stops switching to boost the efficiency until the peak switch current again rises
higher than 0.5 A (typical)
This does appear to be the opposite of FCCM, i.e. pulse skipping mode. Is the webench providing incorrect results here and in reality the part will go into pulse skipping mode, rendering the simulations invalid when webench transitions from CCM to FCCM? This does happen in both Flash and HTML5 versions.