2:1 mux for 2.5 GHz differential clock paths
The 854S01AKILF is a 2:1 differential multiplexer that selects one of two input clock or data signals and routes it to a single LVDS output. It accepts LVDS or LVPECL on the input side and delivers an LVDS-compatible output — the signal standard translation happens inside the mux, so you can feed a LVPECL source into an LVDS receiver without external level shifting. Rated to 2.5 GHz maximum frequency, this part sits in the high-speed serial clock tree where a single reference must be cleanly switched between two sources — for example, selecting between a local oscillator and a recovered clock on a 10 GbE or CPRI line card.
16-VFQFN 3x3 mm — footprint and thermal
Housed in a 16-VFQFN with exposed pad, 3x3 mm body (supplier package 16-VFQFPN). The exposed paddle is the thermal path and the ground return — it must be soldered to a PCB copper pour with via stitching to the inner ground plane. Without that thermal via cluster the junction temperature rises above the 85°C ambient limit when the mux is switching at 2.5 GHz. The 0.50 mm pitch QFN pads fan out to 0.65 mm escape traces on a single inner layer — a two-layer board is feasible if the ground plane under the paddle is continuous. The package height is under 1 mm, so it fits on the back side of a mezzanine card without shadowing the adjacent components. The differential input and output are both rated Yes/Yes, meaning the mux preserves the differential signal path end-to-end; single-ended drive is not supported.