Microchip SY56020R Handleiding


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SY56020R Evaluation Board
Low Voltage 1.2V/1.8/2.5V CML Differential
1:4 Fanout Buffer with Input Equalization
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
October 2008 M9999-100108-A
hbwhelp@micrel.com or (408) 955-1690
General Description
The SY56020R evaluation board is designed for
convenient set-up and quick evaluation. It allows the user
to evaluate the part over the full voltage-range of the part
without requiring any modification to the board.
The evaluation board standard configuration is AC-coupled
inputs with DC-coupled outputs for direct interface to a
50Ω-compatible oscilloscope. For applications that require
a DC-coupled configuration, step-by-step instructions for
modifying the board are included.
All datasheets and support documentation can be found at
Micrel’s web site at: www.micrel.com.
Features
• SY56020R 1.2V/1.8V/2.5V CML outputs
• Single 2.5V VCC with 1.2V/1.8V/2.5V VCCO supply
• AC-coupled configuration for ease-of-use
• I/O interface includes on-board termination
• Fully assembled and tested
• Reconfigurable for DC-coupled operation
Applications
• SY56020R Low Voltage 1.2V to 2.5V CML Differential
1:4 Fan-out Buffer with Input Equalization
___________________________________________________________________________________________________________
Evaluation Board
Micrel, Inc. SY56020R Evaluation Board
October 2008 2 M9999-100108-A
hbwhelp@micrel.com or (408) 955-1690
Evaluation Board Description
The SY56020R evaluation board is designed to accept
either AC-coupled or DC-coupled inputs; however, all
boards are shipped with DC-Coupled outputs. The DC-
coupled outputs allow the CML output to be connected
directly to a scope with the standard termination of 50Ω-
to-ground. This is accomplished by tying the body of the
SMA connectors to the VCCO supply on the evaluation
board so that the scope termination appears as 50Ω-to-
VCCO on the board. This allows the body of the SMA
connectors, which are scope GND, to appear at the
same potential as VCCO for the CML output drivers.
The choice between the two configurations, AC-Coupled
or DC-Coupled inputs, offers the user flexibility in
selecting the board that is right for the given application.
Step-by-step instructions for modifying an AC-coupled
evaluation board for DC-coupled operation are supplied
in the section “Modifying your AC-Coupled Board for DC-
Coupled Operation.”
If the output is connected to an AC-coupled 50Ω
termination, the 1.2V operation may not work due to a
200mV output level shift from the output coupling
capacitors.
SY56020R AC-Coupled Evaluation Board
(AC-Coupled Input, DC-Coupled Output)
For a 1.2V output configuration, the V CC of the board is
set to 2.5V and the VCCO is set to 1.2V. For a 1.8V output
configuration the VCCO is set to 1.8V. For a full 2.5V
operation, short VCCO to VCC. For all configurations the
VEE is set to 0V.
Setting up the AC-Coupled Evaluation Board
(AC-Coupled Input, DC-Coupled Output)
The following steps describe the procedure for setting up
the CML-output evaluation board:
Setting up the Power Supplies:
1. Set the voltage setting of a DC supply to 2.5V and
turn off the supply.
2. Set the voltage setting for a second DC supply to be
1.2V, 1.8V or 2.5V and turn off the supply.
3. 2.5V output operation can also be achieved by
shorting VCCO to VCC and operating with one supply.
4. Connect the negative terminal of the two power
supplies together and connect to the VEE terminal of
the evaluation board.
5. Do not earth ground either supply.
6. Turn on the power supplies and verify that the 2.5V
supply current is <90mA and 1.2V/1.8V/2.5V supply
is <90mA. If using one supply, <180mA.
7. Turn off the power supplies.
Setting up the AC-Coupled Input
1. Using a differential signal source set the HIGH level
of each side of the differential pair to be 0.4V and
the LOW level to be 0V. Note that for AC-coupled
inputs, only the signal swing is significant, since the
input will be re-biased after the series capacitor. The
amplitude of the input swing can be any value
between 200mV and 1.0V.
2. Using equal length 50Ω impedance coaxial cables,
connect the signal source to the desired attenuation
line and then connect to the input, IN and /IN, on the
evaluation board. Make sure the length of each
attenuation line is matched to each other.
3. The equalization can be selected through the EQ pin
(Pin 4), which is connected to the J15 jumper. The
EQ setting depends on the length of the attenuation
line. Please refer to Table 1 below for the desired
equalization selection.
EQ FR4 EQUALIZATION
LOW( L ) 9”
FLOAT 18”
HIGH( H ) 27”
Table 1. EQ Setting
Setting up the DC-Coupled Output
1. Using equal length 50Ω impedance coaxial cables
connect one of the SMA output pairs of the
evaluation board (Pin 15 and Pin 14 for Q0, Pin12
and Pin 11 for Q1, Pin 10 and Pin 9 for Q2, Pin 7
and Pin 6 for Q3) to the oscilloscope or other
measurement device that has an internal DC-
Coupled 50Ω termination. If only one true output is
connected to the oscilloscope, the complementary
output must still be terminated with a 50Ω
termination. Terminate all unused outputs into 50Ω,
otherwise reflections will distort the waveform being
monitored.
2. Turn on the power supplies and verify that the 2.5V
supply current is <90mA and 1.2V/1.8V/2.5V supply
is <90mA. And <180mA if using one supply.
3. Enable the signal source and monitor the outpu
Micrel, Inc. SY56020R Evaluation Board
October 2008 3 M9999-100108-A
hbwhelp@micrel.com or (408) 955-1690
Evaluation Board
SY56020R AC-Coupled Evaluation Board
Power Supply VCC VCCO VEE I/O
1.2V Output 2.5V 1.2V 0V AC-Coupled Input/DC-Coupled Output
1.8V Output 2.5V 1.8V 0V AC-Coupled Input/DC-Coupled Output
2.5V Output 2.5V 2.5V 0V AC-Coupled Input/DC-Coupled Output
Table 2. SY56020R AC-Coupled Evaluation Board Power Supply Connections


Product specificaties

Merk: Microchip
Categorie: Niet gecategoriseerd
Model: SY56020R

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