SY89838U Datasheet, PDF (1/16 Pages) Micrel Semiconductor – Precision 1:8 LVDS Clock Fanout Buffer with 2:1 Runt Pulse Eliminator Input MUX

SY89838U
Precision 1:8 LVDS Clock Fanout Buffer
with 2:1 Runt Pulse Eliminator Input MUX
General Description
The SY89838U is a low jitter, low skew, high-speed
1:8 fanout buffer with a unique, 2:1 differential input
multiplexer (MUX) optimized for redundant source
switchover applications. Unlike standard
multiplexers, the SY89838U unique 2:1 Runt Pulse
Eliminator (RPE) MUX prevents any short cycles or
“runt” pulses during switchover. In addition, a unique
fail-safe input protection prevents metastable
conditions when the selected input clock fails to a
DC voltage (voltage between the pins of the
differential input drops below 100mV). The
SY89838U distributes clock frequencies from 1kHz
to 1.5GHz, guaranteed, over temperature and
voltage.
The differential input includes Micrel’s unique, 3-pin
input termination architecture that allows customers
to interface 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. The outputs are 350mV compatible
LVDS with fast rise/fall times guaranteed to be less
than 150ps.
The SY89838U operates from a 2.5V ±5% supply
and is guaranteed over the full industrial
temperature range of –40°C to +85°C. For
applications that require 800mV LVPECL outputs,
consider the SY89837U. The SY89838U 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 two clocks, and provides 8
precision, low skew LVDS output copies
• 2:1 MUX input provides a glitch-free, stable LVDS
output
• Guaranteed AC performance over temperature
and supply voltage:
– Wide operating frequency: 1kHz to >1.5GHz
– <150ps t_r/t_f
– <40ps output-to-output skew
• Unique patent-pending input isolation design
minimizes crosstalk
• Fail-safe input prevents oscillation
• Ultra-low jitter design:
– <1ps_RMS random jitter
– <1ps_RMS cycle-to-cycle jitter
– <10ps_PP total jitter (clock)
– <0.7ps_RMS MUX crosstalk induced jitter
• Unique patent-pending input termination and VT
pin accepts DC- and AC-coupled inputs (CML,
PECL, LVDS)
• 350mV LVDS output swing
• Power supply 2.5V +5%
• –40°C to +85°C industrial temperature range
• Available in 32-pin (5mm x 5mm) MLF^® package
Applications
• Redundant clock switchover
• Failsafe clock protection
Markets
• LAN/WAN
• Enterprise Servers
• ATE
• Test and Measurements
Precision Edge is a registered trademark of Micrel, Inc
MicroLeadFrame and MLF are registered trademarks of Amkor Technology, Inc.
September 2006
M9999-091906-B
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