Low Power, 3GHz, 1:2 LVPECL Fanout Buffer/Translator w

Low Power, 3GHz, 1:2 LVPECL Fanout
Buffer/Translator w/ Internal Termination
SY89851U Evaluation Board
General Description
Features
The SY89851U evaluation board is designed for
convenient setup and quick evaluation of the device.
The boards are optimized to interface directly to a
50Ω oscilloscope.
• SY89851U
The default evaluation board I/O configuration is ACcoupled. For applications that requires DC-coupled
mode, instructions for modifying the board are
included.
• Evaluation board re-configurable for DC-coupled
output
Data sheets and support documentation can be found
on Micrel’s web site at www.micrel.com.
• Single +2.5V or +3.3V power supply
• AC-coupled input and output configuration for
easy evaluation
• Fully assembled and tested
Related Documentation
• SY89851U, Low Power, 3GHz, 1:2 LVPECL
Fanout Buffer/Translator with Internal Termination
Data Sheet
____________________________________________________________________________________
Evaluation Board
August 2004
M9999-082404
[email protected] or (408) 955-1690
Micrel
SY89851U Evaluation Board
DC-Coupled Evaluation Board
Evaluation Board Description
The SY89851U evaluation board can be configured in
DC-coupled mode by removing capacitors C8-C11
and replacing the components with 0Ω resistors.
AC-Coupled Evaluation Board
The SY89851U is packaged in a 16-pin MLFTM. The
SY89851U evaluation board is designed to operate
with a single 2.5V±5% or 3.3V±10% power supply
and is configured in AC-coupled mode.
Interfacing to 50Ω Lab Equipment
Interfacing the board to 50Ω lab equipment in DCcoupled mode involves using split supplies.
The high-speed input channels are brought out to
SMA connectors through matched length AC-coupled
differential strip-line traces. The DC-operating point is
set at VCC–1.3V by the VREF-AC output pin, which is
connected to the VT input of the device. The outputs
are brought out to SMA connectors through matched
length AC-coupled differential strip-line traces, which
allow the board to interface directly with 50Ω lab
equipment. Although the evaluation board’s default
mode is AC-coupled the evaluation board can be
reconfigured in DC-coupled mode by modifying the
board.
2.5V Split Supply Configuration:
•
VCC = 1.2V
•
GND = 0V
•
VEE = –1.3V
3.3V Split Supply Configuration:
•
VCC = 1.2V
•
GND = 0V
•
VEE = –2.1V
AC-Coupled Input
Interfacing to LVPECL Systems
It is recommended that the input be left in AC-coupled
input mode for ease of use. In this mode, signals will
automatically bias to the correct DC-operating point,
which is VCC-1.3V since VREF-AC is connected to the VT
input. Therefore, the inputs can be driven by a
differential signal as small as 100mV (200mVpp)
without any level shifting or termination resistor
network in the signal path.
Interfacing a DC-coupled output to a LVPECL system
requires a single power supply source.
Single Power Supply Setup:
•
VCC = 2.5/3.3V
•
GND = 0V
•
VEE = 0V
Unused outputs
•
Single-ended to scope
Unused compliment output should be
terminated into 50Ω to ground.
•
Unused output pairs
Unused pairs can be left floating with no
impact on jitter.
August 2004
2
M9999-082404
[email protected] or (408) 955-1690
Micrel
SY89851U Evaluation Board
Evaluation Board
SY89851U AC-Coupled LVPECL Evaluation Board
Supply Voltage
2.5V/3.3V
2.5V
3.3V
I/O
VCC
GND
VEE
C8-C11
(1)
2.5/3.3V
0
0
0.1µF
(2)
1.2V
0
–1.3V
0Ω
(2)
1.2V
0
–2.1V
0Ω
AC-Coupled Input/AC-Coupled Output
AC-Coupled Input/DC-Coupled Output
AC-Coupled Input/DC-Coupled Output
Table 1. SY89851U Evaluation Board Setup
Note:
1.
Default setting.
2.
Remove capacitors at C8-C11 and replace with 0Ω 0402 resistors.
August 2004
3
M9999-082404
[email protected] or (408) 955-1690
Micrel
SY89851U Evaluation Board
AC-Coupled Evaluation Board Setup
Setting up the Evaluation Board
3. Turn off or disable the outputs of the signal
source.
The following steps describe the procedure for setting
up the evaluation board:
4. Using equal length 50Ω impedance coaxial
cables, connect the signal source to the
inputs on the evaluation board.
1. Set VCC to 2.5 or to 3.3V, and GND and VEE
to 0V, and turn off the supply.
5. Using equal length 50Ω impedance coaxial
cables, connect the outputs of the evaluation
board to an oscilloscope or other lab
equipment with internal 50Ω termination.
2. Using a differential signal source set the
amplitude to 400mV (single-ended) or
800mV (differential). Set the offset to a
positive value, the value of the offset is not
critical, since the AC-coupled inputs will
automatically bias to the VT voltage.
August 2004
6. Enable the signal source and monitor the
outputs.
4
M9999-082404
[email protected] or (408) 955-1690
Micrel
SY89851U Evaluation Board
Bill of Materials
Item
Part Number
Manufacturer
(1)
Description
Qty.
C1, C3, C5-C11
VJ0402Y104KXXAT
Vishay
0.1µF, 25V, 10% Ceramic Capacitor, Size
0402, X7R Dielectric
9
C2, C4
293D685X0010
Vishay(1)
6.8µF, 20V, Tantalum Electrolytic Capacitor,
Size C
2
J1
111-0703-001
Johnson
Components(2)
Black Banana Jack
1
J2
111-0702-001
Johnson
Components(2)
Red Banana Jack
J3
111-0701-001
Johnson
Components(2)
White Banana Jack
1
SW
CT2182LPST-ND
2-Position Dip
1
SMA1-SMA6
142-0701-851
Jack Assembly End Launch SMA
6
U1
SY89851U
Low Power, 3GHz, 1:2 LVPECL Fanout
Buffer/Translator with Internal Termination
1
Digi-Key (3)
Johnson
Components(2)
Micrel(4)
Notes:
1.
Vishay: www.vishay.com
2.
Johnson Components: www.johnsoncomponents.com
3.
Digi-Key: www.digikey.com
4.
Micrel: www.micrel.com
August 2004
5
M9999-082404
[email protected] or (408) 955-1690
Micrel
SY89851U Evaluation Board
Evaluation Board Layout
PC Board Layout
Layer
SY89851U
The evaluation boards are constructed with Rogers
4003 material and are coplanar in design and
fabricated to minimize noise, achieve high bandwidth
and minimize crosstalk.
L1
GND and Signal
L2
GND
L3
VCC and VEE
L4
GND
Table 2. Layer Stack
August 2004
6
M9999-082404
[email protected] or (408) 955-1690
Micrel
SY89851U Evaluation Board
Micrel Cross Reference
Application Hints and Notes
To find an equivalent Micrel part, go to Micrel’s
website at: http://www.micrel.com and following the
steps below:
For application notes on high speed termination on
PECL and LVPECL products, clock synthesizer
products, SONET jitter measurement, and other High
Bandwidth product go to Micrel’s website at
http://www.micrel.com/. Once in Micrel’s website,
follow the steps below:
1. Click on Dynamic Cross Reference
2. Enter competitor’s part number in the
Dynamic Cross Reference field
1. Click on “Product Info”.
2. In the Applications Information Box, choose
“Application Hints and Application Notes.”
3. To download a PDF version of this
information, click on the Cross Reference
PDF tab
HBW Support
Hotline: 408-955-1690
Email Support: [email protected]
MICREL, INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for
its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a
product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for
surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant
injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk
and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale.
© 2004 Micrel, Incorporated.
August 2004
7
M9999-082404
[email protected] or (408) 955-1690