SY89844U Precision LVDS Runt Pulse Eliminator 2:1 MUX with 1:2 Fanout and Internal Termination General Description The SY89844U is a low jitter LVDS, 2:1 input multiplexer (MUX) optimized for redundant source switchover applications. Unlike standard Precision Edge multiplexers, the SY89844U unique 2:1 Runt Pulse Features Eliminator (RPE) MUX prevents any short cycles or Selects between two sources, and provides a runt pulses during switchover. In addition, a unique glitch-free, stable LVDS output Fail-Safe Input protection prevents metastable conditions when the selected input clock fails to a Guaranteed AC performance over temperature DC voltage (voltage between the pins of the and supply voltage: differential input drops below 100mV). wide operating frequency: 1kHz to >1.5GHz <870ps In-to-Out t The differential input includes Micrels unique, 3-pin pd <150ps t /t input termination architecture that allows customers r f to interface to any differential signal (AC- or DC- Unique patent-pending input isolation design coupled) as small as 100mV (200mV ) without any minimizes crosstalk pp level shifting or termination resistor networks in the Fail-Safe Input prevents oscillations signal path. The outputs are 325mV LVDS with fast Ultra-low jitter design: rise/fall times guaranteed to be less than 150ps. <1ps random jitter RMS The SY89844U operates from a 2.5V 5% supply cycle-to-cycle jitter <1ps RMS and is guaranteed over the full industrial <10ps total jitter (clock) PP temperature range of 40C to +85C. The <0.7ps MUX crosstalk induced jitter RMS SY89844U is part of Micrels high-speed, Precision Unique patent-pending input termination and VT Edge product line. pin accepts DC- and AC-coupled inputs (CML, All support documentation can be found on Micrels PECL, LVDS) web site at: www.micrel.com. 325mV LVDS output swing 2.5V +5% power supply 40C to +85C industrial temperature range Available in 24-pin (4mm x 4mm) QFN package Applications Redundant clock switchover Fail-safe clock protection Markets LAN/WAN Enterprise servers ATE Test and measurement Precision Edge is a registered trademark of Micrel, Inc. May 2007 M9999-052207-B hbwhelp micrel.com or (408) 955-1690 Micrel, Inc. SY89844U Typical Application Simplified Example Illustrating Runt Pulse Eliminator (RPE) when Primary Clock Fails May 2007 2 M9999-052207-B hbwhelp micrel.com or (408) 955-1690