Line Interface Unit for telecom line-side termination
The DS21348TN+ is a single-channel Line Interface Unit (LIU) from Analog Devices, designed for the physical-layer interface between a digital telecom line and the framer or controller. It operates from a 3.135V to 3.465V supply, drawing 66mA typical.
Package and thermal integration
Housed in a 44-TQFP (10x10 mm) package with a 0.8 mm pitch, the DS21348TN+ mounts on standard surface-mount pads. The exposed paddle must be soldered to a ground-plane copper pour for thermal dissipation — the TQFP-44 body alone does not shed the 66mA load heat without the pad connection.
No official second-source or pin-compatible alternative is listed — the BOM carries single-source risk for this LIU.