Clock fanout for PCIe and SATA reference trees
The LMK00338RTAT is a 3:9 differential clock buffer from Texas Instruments, designed to distribute reference clocks for PCI Express and SATA CPU interfaces. It accepts a wide range of input formats — CML, HCSL, HSTL, LVDS, LVPECL, SSTL, or a crystal — and outputs HCSL or LVCMOS, all with differential I/O (Yes/Yes). With a maximum frequency of 400 MHz, this part covers PCIe Gen1 (2.5 GT/s), Gen2 (5 GT/s), and Gen3 (8 GT/s) reference clocks, as well as SATA up to 6 Gbps. The 3:9 ratio means three input channels feed nine output copies — enough to distribute a clean clock to multiple endpoints on a server motherboard or switch fabric.
Supply rails and temperature grade
Operating from a single 3.15 V to 3.45 V supply, the LMK00338RTAT runs on a standard 3.3 V rail common in digital systems. The 40-WFQFN package with exposed pad (6x6 mm) requires a thermal land on the PCB to sink heat from the die.