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SY89845U Datasheet, PDF (1/18 Pages) Micrel Semiconductor – PRECISION CML RUNT PULSE ELIMINATOR 2:1 MUX WITH 1:2 FANOUT AND INTERNAL TERMINATION | |||
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SY89845U
Precision CML Runt Pulse Eliminator 2:1 MUX
with 1:2 Fanout and Internal Termination
General Description
The SY89845U is a low jitter CML, 2:1 differential
input multiplexer (MUX) optimized for redundant
source switchover applications. Unlike standard
multiplexers, the SY89845U unique 2:1 Runt Pulse
Eliminator (RPE) MUX prevents any short cycles or
âruntâ 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 differential input includes Micrelâs unique, 3-pin
input 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 400mV CML with fast
rise/fall times guaranteed to be less than 80ps.
The SY89845U operates from a 2.5V ±5% or 3.3V
±10% supply and is guaranteed over the full
industrial temperature range of â40°C to +85°C. The
SY89845U is part of Micrelâs high-speed, Precision
Edge® product line.
All support documentation can be found on Micrelâs
web site at: www.micrel.com.
Features
Precision Edge®
⢠Selects between two sources, and provides a glitch-
free, stable CML output
⢠Guaranteed AC performance over temperature and
supply voltage:
â Wide operating frequency: 1kHz to >1.5GHz
â < 840ps In-to-Out tpd
â < 80ps tr/tf
⢠Unique, patent-pending input isolation design
minimizes crosstalk
⢠Fail-Safe Input prevents oscillations
⢠Ultra-low jitter design:
â <1psRMS random jitter
â <1psRMS cycle-to-cycle jitter
â <10psPP total jitter (clock)
â <0.7psRMS MUX crosstalk induced jitter
⢠Unique patented input termination and VT pin accepts
DC- and AC-coupled inputs (CML, PECL, LVDS)
⢠400mV CML output swing
⢠2.5V ±5% or 3.3V ±10% supply voltage
⢠-40°C to +85°C industrial temperature range
⢠Available in 24-pin (4mm x 4mm) MLF⢠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.
MLF and MicroLeadFrame are trademarks of Amkor Technology, Inc.
Micrel Inc. ⢠2180 Fortune Drive ⢠San Jose, CA 95131 ⢠USA ⢠tel +1 (408) 944-0800 ⢠fax + 1 (408) 474-1000 ⢠http://www.micrel.com
May 2005
M9999-052405
hbwhelp@micrel.com or (408) 955-1690
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