UCC28950EVM-442(#2): 12V @ 50A, 390VDC in

This 600-W EVM was designed to demonstrate how the UCC28950 control device could be used in high-efficiency applications by achieving ZVS from 50% to 100% load. To achieve this high efficiency the UCC28950 was designed to drive synchronous rectifiers on the secondary side of the full bridge converter. The UCC28950 also incorporates a burst mode and DCM function to improve no-load efficiency. Please see UCC28950 data sheet for details (TI Literature Number SLUSA16).

The DCM (Discontinues Current Mode) comparator was designed to turn off the synchronous rectifiers before the output current reaches critical conduction at lighter loads (< 20%). This does two things. First it removes the energy that is required to drive the FETs at lighter loads. Second the DCM feature prevents the output inductor from developing a negative current that can damage the output synchronous rectifiers under no load/transient conditions.