Parametric identity and BOM fit
The FM25L04B-DG is a 4Kbit non-volatile FRAM from Infineon's F-RAM series, organized as 512 x 8 bits. For a data logger or event counter that writes every power cycle, the difference in firmware complexity and throughput is material.
Housed in an 8-WDFN exposed pad package, the FM25L04B-DG occupies a 4x4.5 mm footprint (8-DFN). Supplied in tube format; the same die is also available in tape-and-reel as FM25L04B-DGTR and FM25L04B-GTR. If your pick-and-place line is set up for reel feed, qualifying the tape-and-reel variant saves a manual tube-handling step with no change to the PCB footprint or electrical behavior.
The base product number FM25L04 covers the full family; the suffix -DG denotes the 8-DFN package and tube delivery. No second-source cross-reference is listed, but the part is single-sourced from Infineon — factor that into BOM risk if the line cannot tolerate a sole-source FRAM.