Part documentation for SM5K4 in PDF format, around 235 KB in size. The file name states the device code only, with no brand, package variant or document revision. Repair technicians rely on such a datasheet to read the pinout, understand internal block functions, confirm supply and signal levels, and identify equivalent replacements. Before measuring or swapping anything, make sure the marking on the board's component really corresponds to this SM5K4 part rather than a lookalike from another vendor.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @datasheet_technar_org. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.