Filed as a schematic, this 531 KB PDF carries only the bare number 28040 in its name, with no manufacturer, device model or revision stated. Treat it as unidentified until you open it and read the title block or header. Numeric names in this style usually point to a single part number, so the content is more likely a component reference sheet than a board-level diagram. Use it to check pinouts, supply voltages and timing values, and compare the marking on the physical chip against the document before using it.
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 @cyberlanelectonik. 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.