Attached is a universal input power supply that is designed into a U-frame of 3/32" aluminium measuring 1.5" high by 3.75" wide by 8" long. The TOP261YN is mounted midway on one side with a series 400 Sil-Pad(R) and a CLP-212G spring clip.
The design will be operating in air-conditioned environments, so the ambient air should be kept between 23 and 27 C.
The measured efficiency of this design is 85% on the 12.5V output and 82% on the 55V output. I have yet to figure out how to model this design for absolute worst case power dissipation and temperature rise. So far, a couple dozen units have been built and tested without problems, but I'd like to have a better handle on the probability of units that do have thermal shutoff issues that might develop in less than 60 minutes at full power.