Hello,
We've created a design with LTPowerCad II for the LTC3769. It is designed to output 2A at 55.7V with a 20V input. The design mostly works, but the efficency is substantially lower than the tool suggests it should be. We are measuring an 88% efficiency when the design tool suggested it should be above 97%. This severely limits the power the design can output.
The inductor seems to be wasting way more power in the real world than in the simulation. It exceeds 130°C (more than 100°C above ambient) when outputing 0.7A (less than half what we would like the circuit to output). The desighn tool suggests it should only be loosing about 0.16W which I would not expect to result in such a high temperature rise. The other components in the design remain at a reasonable temperature above ambient.
We used the exact same components as recommended by the tool: XAL7070-182MEB for the inductor and NTMFS5H610NL for the transistors. The layout follows the guidlines in the datasheet.
I've attached a PDF of the LTPowerCad deisgn (the raw file cannot be uploaded) as well as an image of our real-world layout below.
