SY89842U Precision CML Runt Pulse Eliminator 2:1 Multiplexer General Description The SY89842U is a low jitter CML, 2:1 differential input multiplexer (MUX) optimized for redundant source switchover applications. Unlike standard Precision Edge multiplexers, the SY89842U unique 2:1 Runt Pulse Features Eliminator (RPE) MUX prevents any short cycles or Selects between two sources, and provides a glitch- runt pulses during switchover. In addition, a unique free, stable CML output Fail-Safe Input protection prevents metastable conditions when the selected input clock fails to a Guaranteed AC performance over temperature and DC voltage (voltage between the pins of the supply voltage: differential input drops below 100mV). Wide operating frequency: 1kHz to >1.5GHz The differential input includes Micrels unique, 3-pin < 840ps In-to-Out t pd input termination architecture that allows customers < 80ps t /t 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 PP minimizes crosstalk level shifting or termination resistor networks in the Fail-safe input prevents oscillations signal path. The output is 400mV CML with fast Ultra-low jitter design: rise/fall times guaranteed to be less than 80ps. <1ps random jitter RMS The SY89842U operates from a 2.5V 5% or 3.3V <1ps cycle-to-cycle jitter RMS 10% supply and is guaranteed over the full <10ps total jitter (clock) PP industrial temperature range of 40C to +85C. The MUX crosstalk induced jitter <0.7ps RMS SY89842U is part of Micrels high-speed, Precision Unique patent-pending input termination and VT pin Edge product line. All support documentation can accepts DC- and AC-coupled inputs (CML, PECL, www.micrel.com. be found on Micrels web site at: LVDS) 400mV CML output swing 2.5V 5% or 3.3V 10% supply voltage -40C to +85C industrial temperature range Available in 16-pin (3mm x 3mm) 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. Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel, Inc. SY89842U Typical Application Simplified Example Illustrating Runt Pulse Eliminator (RPE) Circuit when Primary Clock Fails March 2005 2 M9999-030805 hbwhelp micrel.com or (408) 955-1690