What this PCIe clock buffer does on the board
The Renesas 9DB403DGLFT is a 1:4 differential clock buffer with an integrated PLL, designed to clean and fan out a PCI Express reference clock. It takes a single HCSL input and delivers four HCSL or LVDS outputs at up to 400 MHz, covering PCIe Gen1 through Gen3 base frequencies. The 3.135 V to 3.465 V supply rail and 0°C to 70°C operating range target it squarely at commercial server, storage, and networking line cards — not industrial or outdoor gear.
400 MHz ceiling and 1:4 fanout — the fit decision
At 400 MHz max, this buffer handles PCIe Gen3 (8 GT/s) reference-clock duty without margin for Gen4 or Gen5 rates. The 1:4 ratio drives four loads from one input; if your BOM calls for eight downstream devices, the 9DB803DFLFT (1:8, same 400 MHz cap) is the direct drop-in step-up.
Active lifecycle — no last-time-buy watch needed
Because this is an active, commercial-temperature PCIe buffer, it is sourced through standard independent distribution channels. The 28-TSSOP body (4.40 mm width) is a common surface-mount package that reflows on a standard lead-free profile. No special handling or moisture-sensitivity beyond the standard MSL level for TSSOP is expected, but verify the bake requirements if the part has been in storage.