NOT RECOMMENDED FOR NEW DESIGNS 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
“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 differential input includes Micrel’s unique, 3-pin
input termination architecture that allows customers
to interface to any differential signal (AC-or DCcoupled) 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 В±5% or 3.3V
В±10% supply and is guaranteed over the full
industrial temperature range of –40°C to +85°C. The
SY89845U is part of Micrel’s high-speed, Precision …
