PDF reference document named TPS4202, around 1 MB. The name gives only a part designation with no device or board, so it is most likely a datasheet or application material for that component rather than a full board schematic. Technicians use such documents to identify pinout, check expected voltages on each pin, and understand typical circuits while testing or replacing the chip. Confirm the marking on the actual chip matches before relying on values, and open it in any PDF reader.
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 @datasheets1. 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.