841608

FemtoClock® Crystal-to-HCSL Clock Generator 841608 Datasheet General Description The 841608 is an optimized PCIe and sRIO clock generator. The device uses a 25MHz parallel crystal to generate 100MHz and 125MHz clock signals, replacing solutions requiring multiple oscillator and fanout buffer solutions. The device has excellent phase jitter (< 1ps rms) suitable to clock components requiring precise and low-jitter PCIe or sRIO or both clock signals. Designed for telecom, networking and industrial applications, the 841608 can also drive the high-speed sRIO and PCIe SerDes clock inputs of communication processors, DSPs, switches and bridges. Features Eight HCSL outputs: configurable for PCIe (100MHz) and sRIO (125MHz) clock signals Selectable crystal oscillator interface, 25MHz, 18pF parallel resonant crystal or LVCMOS/LVTTL single-ended reference clock input Supports the following output frequencies: 100MHz or 125MHz VCO: 500MHz PLL bypass and output enable PCI Express (2.5 Gb/S) and Gen 2 (5 Gb/s) jitter compliant RMS phase jitter at 125MHz, using a 25MHz crystal (1.875MHz – 20MHz): 0.37ps (typical) Full 3.3V operating supply -40°C to 85°C ambient operating temperature Available in lead-free (RoHS 6) package Block Diagram XTAL_IN XTAL_OUT OSC 0 REF_IN Pulldown 1 REF_SEL Pulldown IREF BYPASS Pulldown FSEL Pulldown FemtoClock PLL VCO = 500MHz 1 0 ÷N ÷4 ÷5 (default) M = ÷20 MR/nOE Pulldown Pin Assignment FSEL IREF BYPASS VDDA REF_SEL REF_IN ...