2:10 fanout at 2.5 GHz — what the ratio and frequency mean for your clock tree
The Renesas 853S111BKILFT is a 2:10 differential fanout buffer and multiplexer that accepts LVDS, LVPECL, or SSTL inputs and drives ECL or PECL outputs. Its 2.5 GHz maximum frequency covers 10 GbE reference clocks, JESD204B SYSREF, and RF sampling clocks up to the 2.5 GHz ceiling. The 2:10 fanout ratio means one device can feed ten receiver banks from either of two selectable input sources — useful for redundant clock paths or multi-card backplanes where you need to distribute a clean copy to every slot without adding a second buffer stage.
Supply range and temperature grade — board-level fit
The 2.375 V to 3.8 V supply range lets the 853S111BKILFT run from a 2.5 V or 3.3 V rail directly, which is common in FPGA and SerDes clock domains. The -40°C to 85°C operating temperature covers industrial environments — outdoor telecom cabinets, base stations, and factory-floor equipment where the ambient inside the enclosure can hit 70°C. The 32-VFQFN package with exposed pad (5x5 mm footprint) needs a thermal via pattern under the pad for heat sinking; the datasheet's recommended land pattern is the starting point for the PCB layout.
Input and output standards — what connects where
The input stage accepts three differential families: LVDS (common in FPGA clock outputs), LVPECL (traditional high-speed clock distribution), and SSTL (memory interface clocks). The outputs are ECL or PECL, which are the standard levels for driving clock trees into SerDes transceivers, FPGA clock inputs, and data converters. Because the part is fully differential on both sides, it rejects common-mode noise on long board traces — important when the clock source is on a different card or a distant oscillator.
Lifecycle and sourcing
The 853S111BKILFT is listed as Active and RoHS3 compliant.