Microchip SY89837U Bedienungsanleitung


Lesen Sie kostenlos die đź“– deutsche Bedienungsanleitung fĂĽr Microchip SY89837U (8 Seiten) in der Kategorie Nicht kategorisiert. Dieser Bedienungsanleitung war fĂĽr 3 Personen hilfreich und wurde von 2 Benutzern mit durchschnittlich 4.5 Sternen bewertet

Seite 1/8
November 2004
M9999-110804
hbwhelp@micrel.com or (408) 955-1690
Precision 1:8 LVPECL Fanout Buffer with
2:1 Runt Pulse Eliminator Input MUX
SY89837U Evaluation Board
General Description
The SY89837U evaluation board is designed for
convenient setup and quick evaluation of the
SY89837U. The boards are optimized to interface
directly to a 50Ω oscilloscope.
For best AC performance, the boards are configured
in AC-coupled In/AC-coupled Out configuration. For
applications that require a DC-coupled configuration,
step-by-step instructions for modifying the board are
included.
Features
• Fully assembled and tested SY89837U
• +2.5V or +3.3V power supply
• AC-coupled configuration for ease-of-use
• I/O interface includes on-board termination
• Fully assembled and tested
• Can be reconfigured for DC-coupling operation
Related Documentation
• SY89837U, Precision 1:8 LVPECL Fanout Buffer
with 2:1 Runt Pulse Eliminator Input MUX
___________________________________________________________________________________
Evaluation Board
Micrel
SY89837U Evaluation Board
November 2004
M9999-110804
hbwhelp@micrel.com or (408) 955-1690
2
Evaluation Board Description
The default configuration for the SY89837U board is
the AC-coupled. The choice between AC- and DC-
coupled configurations offers the user flexibility for
specific applications.
AC-Coupled Evaluation Board
The AC-coupled configuration is suited to most
customer applications and is preferred by the majority
of users because of its ease-of-use. It requires only a
single power supply and offers the most flexibility in
interfacing to a variety of signal sources.
The DC-bias levels and AC-coupling capacitors are
supplied on-board for each input, making it
unnecessary to vary the offset voltage or change any
components on the board as the power supply
voltage varies over the +2.5V +5% and +3.3V +10%
operating range. The user needs only to supply a
minimum input voltage swing and the bias voltage will
automatically adjust the input to the correct level as
the power supply voltage varies.
DC-Coupled Evaluation Board
For applications that are not suited to AC-coupling
such as clock that can be turned off for extended
periods of time, the board can be user-configured for
DC-coupled operation.
This can be accomplished by modifying the board to
use two power supplies into a “split-supply
configuration.” Since LVPECL is referenced to V
CC
,
and standard PECL termination is 50 to V
CC
–2V,
split-supply is an easy method to interface to a 50
(to ground) scope. Therefore, a 3.3V supply will be
split into +2V and –1.3V, and a 2.5V supply will be
split into a +2V and –0.5V.
The +2V offset in this two-power supply configuration
then provides the correct terminations for the device
by setting the Ground potential on the board to be
exactly 2 volts below the V
CC
supply. The V
EE
voltage
is then set to –1.3V for 3.3V devices, or –0.5V for
2.5V devices to ensure proper V
CC
to V
EE
voltage
difference.
Runt Pulse Eliminator Input
The SY89837U evaluation board allows the user to
test the Runt Pulse Eliminator function. The Runt
Pulse Eliminator function prevents any short cycles or
“runt” pulses during switchover.
To see the effects of the Runt Pulse Eliminator
function, disable it by replacing C11 with a 0
resistor. Sweep the frequency of the function
generator to see runt pulses develop. Enable the
Runt Pulse Eliminator function by restoring C11, and
perform the same frequency sweep.
Any-Input Interface
The unique internal input termination sets the input
common mode voltage. This enables the input to
interface with any differential signal over the supply
voltage without modifying the board.
Micrel
SY89837U Evaluation Board
November 2004
M9999-110804
hbwhelp@micrel.com or (408) 955-1690
3
Evaluation Board
SY89837U AC-Coupled Evaluation Board
Power Supply V
CC
GND V
EE
I/O
2.5 Volt System +2.5V 0V 0V AC-coupled Input/AC-coupled Output
3.3 Volt System +3.3V 0V 0V AC-coupled Input/AC-coupled Output
Table 1. AC-Coupled Evaluation Board Power Supply Connections


Produktspezifikationen

Marke: Microchip
Kategorie: Nicht kategorisiert
Modell: SY89837U

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