ICS844256

www.DataSheet4U.com PRELIMINARY Integrated Circuit Systems, Inc. ICS844256 FEMTOCLOCKS™CRYSTAL-TO-LVDS FREQUENCY SYNTHESIZER W/INTEGRATED FANOUT BUFFER FEATURES Six LVDS outputs Crystal oscillator interface Output frequency range: 62.5MHz to 622.08MHz Crystal input frequency range: 15.625MHz to 25.5MHz RMS phase jitter at 125MHz, using a 25MHz crystal (1.875MHz to 20MHz): 0.48ps (typical) Full 3.3V or 3.3V core, 2.5V output supply mode 0°C to 70°C ambient operating temperature Industrial temperature information available upon request Available in both standard and lead-free RoHS-compliant packages Function GENERAL DESCRIPTION The ICS844256 is a Crystal-to-LVDS Clock Synthesizer/Fanout Buffer designed for SONET HiPerClockS™ and Gigabit Ethernet applications and is a member of the HiperClockS™ family of High Performance Clock Solutions from ICS. The output frequency can be set using the frequency select pins and a 25MHz crystal for Ethernet frequencies, or a 19.44MHz crystal for SONET. The low phase noise characteristics of the ICS844256 make it an ideal clock for these demanding applications. IC S SELECT FUNCTION TABLE Inputs FB_SEL 0 0 0 0 1 1 1 1 N_SEL1 0 0 1 1 0 0 1 1 N_SEL0 0 1 0 1 0 1 0 1 M Divide 25 25 25 25 32 32 32 32 N Divide 1 2 4 5 1 2 4 8 M/N 25 12.5 6.25 5 32 16 8 4 BLOCK DIAGRAM Q0 nQ0 PLL_BYPASS Pullup PIN ASSIGNMENT VDDO VDDO nQ2 Q2 nQ1 Q1 nQ0 Q0 PLL_BYPASS V DDA VDD FB_SEL 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 ...