SY89843U Precision LVPECL Runt Pulse Eliminator 2:1 MUX with 1:2 Fanout and Internal Termination General Description The SY89843U is a low jitter PECL, 2:1 differential input Precision Edge multiplexer (MUX) optimized for redundant source Features switchover applications. Unlike standard multiplexers, the SY89843U unique 2:1 Runt Pulse Eliminator (RPE) Selects between two sources, and provides a MUX prevents any short cycles or runt pulses during glitch-free, stable LVPECL output switchover. In addition, a unique Fail-Safe Input Guaranteed AC performance over temperature protection prevents metastable conditions when the and supply voltage: selected input clock fails to a DC voltage (voltage Wide operating frequency: 1kHz to >1.5GHz between the pins of the differential input drops below < 880ps In-to-Out t pd 100mV). < 190ps t /t r f The differential input includes Micrels unique, 3-pin Unique patent-pending input isolation design input termination architecture that allows customers to minimizes crosstalk interface to any differential signal (AC- or DC-coupled) Fail-Safe Input prevents oscillations as small as 100mV (200mV ) without any level shifting PP Ultra-low jitter design: or termination resistor networks in the signal path. The 65fs RMS phase jitter (Type) output is 800mV, 100K compatible LVPECL with fast 0.7ps MUX crosstalk induced jitter RMS rise/fall times guaranteed to be less than 190ps. Unique patent-pending input termination and VT The SY89843U operates from a 2.5V 5% or 3.3V pin accepts DC- and AC-coupled inputs (CML, 10% supply and is guaranteed over the full industrial PECL, LVDS) temperature range of 40C to +85C. The SY89843U is 800mV LVPECL output swing part of Micrels high-speed, Precision Edge product 2.5V 5% or 3.3V 10% supply voltage line. All support documentation can be found on Micrels 40C to +85C industrial temperature range web site at: www.micrel.com. Available in 24-pin (4mm x 4mm) QFN package Applications Redundant clock switchover Failsafe clock protection Markets LAN/WAN Enterprise servers ATE Test and measurement Precision Edge is a registered trademark of Micrel, Inc. Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel, Inc. SY89843U Typical Application Simplified Example Illustrating RPE (Runt Pulse Elimination) Circuit when Primary Clock Fails 2 M9999-052207-B Oct. 1, 2013 hbwhelp micrel.com or (408) 955-1690