Datasheet for the Atmel ATxmega D4 series, the 44-pin devices of the AVR XMEGA D family. The 3.54 MB PDF covers pinout, alternate port functions, memory configuration, package outlines, DC and AC parameters and errata. Register-level descriptions are kept in the separate XMEGA D manual. Technicians rely on it to find the PDI programming pins, supply connections and reset line when diagnosing or reflashing a board. Supply voltage must stay within the low-voltage XMEGA range, around 1.6 to 3.6 V.
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. 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.