General Description
The SY89464U is a low jitter 1:10 LVPECL fanout buffer with a 2:1 differential input multiplexer (MUX) optimized for redundant source switchover applications. Unlike standard multiplexers, the SY89464U’s unique 2:1 Runt Pulse Eliminator (RPE) MUX prevents any short cycles or “runt” pulses during switchover. In addition, a unique Fail Safe Input (FSI) protection prevents metastable output conditions when the selected input clock fails to a DC voltage (voltage between the pins of the differential input drops below 100mV).
The differential input includes Micrel’s unique, 3-pin internal termination architecture that allows customers to interface to any differential signal (AC or DC-coupled) as small as 100mV (200mVPP) without any level shifting or termination resistor networks in the signal path. The outputs are 800mV, 100K-compatible LVPECL with fast rise/fall times guaranteed to be less than 220ps.
The SY89464U operates from a 2.5V ±5% or 3.3V ±10% supply and is guaranteed over the full industrial temperature range of –40°C to +85°C. The SY89464U is part of Micrel’s high-speed, Precision Edge® product line.

FEATUREs
• Selects between two sources, and provides 10 precision LVPECL copies
• Guaranteed AC performance over temperature and supply voltage:
   – Wide operating frequency: 1kHz to >1.5GHz
   – < 1100ps In-to-Out tpd
   – < 220ps tr/tf
• Unique, patent-pending MUX input isolation design minimizes adjacent channel crosstalk
• Fail-Safe Input prevents oscillations
• Ultra-low jitter design:
   – <1psRMS random jitter
   – <1psRMS cycle-to-cycle jitter
   – <10psPP total jitter (clock)
   – <0.7psRMS MUX crosstalk induced jitter
• Unique patented internal termination and VT pin accepts DC- and AC-coupled inputs (CML, PECL, LVDS)
• 800mV LVPECL output
• 2.5V ±5% or 3.3V ±10% supply voltage
• Output enable
• -40°C to +85°C industrial temperature range
• Available in 44-pin (7mm x 7mm) MLF™ package

APPLICATIONs
• Redundant clock switchover
• Fail-safe clock protection

Markets
• LAN/WAN
• Enterprise servers
• ATE
• Test and measurement