What this LIU does on the board
The DS21348T+ is a single-channel Line Interface Unit (LIU) from Analog Devices, packaged in a 44-TQFP (10x10 mm) surface-mount package supplied in tray format. It functions as a telecom interface IC, handling the physical-layer electrical interface between the line transformer and the framer/mapper in T1//J1 communication links.
Sourcing and compliance posture
For a BOM that requires a second-source hedge, a parametric search across Analog Devices' LIU portfolio in the same 44-TQFP footprint would be the next step — but no drop-in alternative is documented.
