SY89112U Datasheet, PDF (1/14 Pages) Micrel Semiconductor – 2.5/3.3V Low-Jitter, Low-Skew 1:12 LVPECL Fanout Buffer with 2:1 Input MUX and Internal Termination

SY89112U
2.5/3.3V Low-Jitter, Low-Skew 1:12
LVPECL Fanout Buffer with 2:1 Input MUX
and Internal Termination
General Description
The SY89112U is a low-jitter, low-skew, high-speed
LVPECL 1:12 differential fanout buffer optimized for
precision telecom and enterprise server distribution
applications. The input includes a 2:1 MUX for clock
switchover application. Unlike other multiplexers, this input
includes a unique isolation design to minimize channel-to-
channel crosstalk. The SY89112U distributes clock
frequencies from DC to >2GHz guaranteed over
temperature and voltage. The SY89112U incorporates a
synchronous output enable (EN) so that the outputs will
only be enabled/disabled when they are already in the
LOW state. This reduces the chance of generating “runt”
clock pulses.
The SY89112U differential input includes Micrel’s unique,
patent-pending 3-pin input termination architecture that
directly interfaces to any differential signal (AC- or DC-
coupled) as small as 100mV (200mV_pp) without any level
shifting or termination resistor networks in the signal path.
For AC-coupled input interface, an on-board output
reference voltage (VREF-AC) is provided to bias the
center-tap (VT) pin. The outputs are 800mV, 100K-
compatible LVPECL with fast rise/fall times guaranteed to
be less than 220ps.
The SY89112U 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 SY89112U is
part of Micrel’s high-speed, Precision Edge^® product line.
All support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
Precision Edge^®
• Selects between 1 of 2 inputs, and provides 12
precision, low skew LVPECL output copies
• Guaranteed AC performance over temperature and
voltage:
– DC to >2GHz throughput
– <550ps propagation delay CLK-to-Q
– <220ps rise/fall time
– <25ps output-to-output skew
• Ultra-low jitter design:
– 109fs_RMS phase jitter (typ.)
– <0.7ps_RMS crosstalk induced jitter
• Unique, patent-pending input termination and VT pin
accepts DC-coupled and AC-coupled differential inputs
• Unique, patent-pending 2:1 input MUX provides
superior isolation to minimize channel-to-channel
crosstalk
• 800mV, 100K LVPECL output swing
• Power supply 2.5V +5% or 3.3V +10%
• Industrial temperature range –40°C to +85°C
• Available in 44-pin (7mm x 7mm) QFN package
Applications
• Multi-processor server
• SONET/SDH clock/data distribution
• Fibre Channel distribution
• Gigabit Ethernet clock distribution
Precision Edge is a registered trademark of Micrel, Inc
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
July 2010
M9999-072809-D
[e-mail] or [phone]