PCIe reference clock with integrated PLL
The DSC557-053344KL1T is a PCI Express (PCIe) clock generator from Microchip's DSC557-05 series, built around an integrated PLL to synthesize a clean 100 MHz reference clock from an internal or external source. The PLL locks to the input and generates four differential outputs in either HCSL or LVDS format, covering the two most common signaling standards for PCIe reference clocks. Because the input-to-output ratio is 0:4, this part accepts no single-ended input — it expects a differential reference or uses an internal oscillator. The differential outputs mean the receiver sees a low-jitter, common-mode-rejected clock edge, which is essential for PCIe Gen1/2/3 link stability where the reference clock jitter budget is tight.
Supply, temperature, and package fit
The exposed pad also provides a low-inductance return path for the high-speed output currents — a layout detail that matters when routing the HCSL or LVDS traces to the PCIe slot or endpoint.
The part is RoHS3 compliant, which means it meets the EU RoHS exemption-free standard for lead, mercury, cadmium, and other restricted substances, so it ships without a RoHS exemption statement.