SY88973/SY88982/MIC3001-Based
SFP Module
TXRX_982_R1 Evaluation Board
General Description
This evaluation board is an implementation of the
SFP module in a different form factor with on board
faults indicators (LEDs) and a DB-25 connector for
serial communication. The design uses Micrel's
MIC3001 controller, SY88982 (pin compatible with
SY88782 and SY88932) driver, and SY88973 limiting
amplifier. A picture of the fully bonded board is
shown below.
Data sheets and support documentation can be found
on Micrel’s web site at
www.micrel.com.
Features
•
•
•
Allows for easy and fast evaluation of Micrel’s
chipset for SFP module
On board FAULTs indicators
Easy access to the components for rework and
different options implementation
IC Description
•
SY88982: Low power small form factor (3mm x
3mm) laser driver up to 3.2Gbps data rate and
2.3V compliance voltage. SY88782 is a lower
speed version up to 1.25Gbps.
MIC3001: SFP module controller featuring digital
diagnostic monitoring interface as per SFF-8472
with internal/external calibration and full laser
control with bias and modulation current
compensation for temperature variations using
look up tables.
SY88973: Multi-rate 155-3200Mbps low
sensitivity limiting amplifier.
Related Support Documentation
•
•
•
•
MIC3001 Data Sheet
SY89307 Data Sheet
SY89973 Data Sheet
MIC3000/1 Software User’s Guide
•
•
______________________________________________________________________________
Evaluation Board
TOSA
DFB / FP
ROSA
To Computer Parallel Port
DRIVER
INPUT
L.A.
OUTPUT
September 2004
M9999-092304
hbwhelp@micrel.com
or (408) 955-1690
Micrel
TXRX_982_R1 Evaluation Board
Evaluation Board Setting
Driver Laser Coupling
Table 1 summarizes the setting of the board for the
two configurations, driver DC-coupled or AC-coupled
to the laser.
Configuration
Driver and Laser
DC-Coupled
Driver and Laser
AC-Coupled
Remove
L2, L3, L7, L8,
R14, R6, R13,
C24, C36
Install
Install a 0 at
C24 and C38.
L2, L3, L7, L8,
R14, R6, R13,
C24, C36
SY88843 Limiting Amplifier
The SY88843 limiting amplifier has a signal detect
(SD) indicator. To improve the hysteresis on the
receive signal LOS, remove R2 and install R3, Q6,
and R23. The combination of R3 and R1 will
determine the sensitivity of the transceiver and
hysteresis on the SD. Refer to the application note
entitled "Notes on Sensitivity and hysteresis in
Micrel's Post Amplifiers" available at
http://www.micrel.com/product-info/app_hints+notes.shtml.
TOSA and ROSA Installation
Check the pinout of the laser and receiver and install
them accordingly to the diagrams shown on Figure 1.
Board
Edge
Top Pad
LD Anode
Top Pad
LD Cathode
Top Pad
DATA-
Top Pad GND
Top Pad
DATA+
Bottom Pad
VCC
Bottom Pad
PD Cathode
Bottom Pad
NC
Bottom Pad
RSSI
Table 1. Configuration Settings
Receiver Sensitivity and Hysteresis Setting
SY88973 Limiting Amplifier
The SY88973 limiting amplifier is the default post
amplifier installed on the board. It has a receive signal
LOS indicator. To improve the hysteresis on the
receive signal LOS, install R2 and uninstall R3. The
combination of R2 and R1 will determine the
sensitivity of the transceiver and hysteresis on the
receive signal LOS. Refer to the application note
entitled "Notes on Sensitivity and hysteresis in
Micrel's Post Amplifiers" available at
http://www.micrel.com/product-info/app_hints+notes.shtml.
Figure 1. Mounting of Laser and Receive
September 2004
2
M9999-092304
hbwhelp@micrel.com
or (408) 955-1690
Micrel
TXRX_982_R1 Evaluation Board
Set-Up and Operation
Follow the step-by-step procedure to set-up the board
safely and properly:
1. Connect the on board DB-25 connector to the
parallel port of a computer.
2. Connect the differential input of the laser
driver to DATA output of the pattern generator.
3. Use a multimode fiber jumper, with
appropriate connectors to connect optical
output of the VCSEL to a VOA (variable
optical attenuator) preset to 0dB attenuation.
4. Connect the output of the VOA to the optical
input of the DCA, power-meter, or optical to
electrical converter.
5. Pre-adjust the power supply to 3.3V and turn it
off. Connect TP3 to V
CC
(3.3V) and TP5 to
GND, then turn the power supply ON. The
total current drawn from the power supply
should be less than 300mA.
6. Launch the MIC3000/1 software. The
MIC3001 Optical Transceiver Management
IC
panel opens with
Panels
and
Help
grayed
out and only
Utilities
can be run.
7. Refer to MIC3000/1 Software User’s Guide for
the detailed settings.
8. On the main window select
Utilities
to open
the utilities panel, then select
SCAN
to read
the address of the MIC3001 and
GET
to read
the manufacturer ID, Device ID, and Die
Revision. If there is a failure in reading one of
these parameters, you cannot proceed further.
If all the parameters are read correctly, close
the
Utilities window
to return to the main
window where
Panels
and
Help
are no longer
grayed out.
9. Select
Panels
to display the list of setting
panels.
10. All the bits displayed on the panels can be
read and/or modified on the panels or by
accessing the registers directly by selecting
ALL REGISTERS,
enter the serial address,
the register address, select
GET
to read the
content or type a value and select
SET NEW
to write. In this procedure the bits are set on
the panels.
11. Select
OEM CONFIG 0-2
to open the OEM
configuration registers 0, 1, and 2 windows.
12. In
OEM Configuration Register 0
window,
set
ENABLE/DISABLE
to DISABLE,
VMOD
REFERENCE to GND,
and
temperature
zone
to
INTERNAL.
13.
In
OEM Configuration Register 1
window:
a. Set
APC OP-AMP TYPE
to
COMMON
EMITTER.
Note: Set the selection bit to 0, 0 should correspond
to EMITTER FOLLOWER, which should be displayed
on the bottom and COMMON EMITTER on the top.
b. Select the voltage to report in
VINH:VINL.
c.
Set Feedback voltage source to 1.22V.
d. Set
FEEDBACK BIAS REF and RES
TERMINATION to GND
and
VBIAS
DRIVE
to
SOURCE
(NPN). Set
INTERNAL FEEDBACK RESISTOR
to
an arbitrary value (1.6K for example).
e. Set
FEEDBACK BIAS REF and RES
TERMINATION
to
GND
and
VBIAS
DRIVE
to
SOURCE
(NPN).
f.
Set
INTERNAL FEEDBACK
RESISTOR
to arbitrary value (1.6K for
example).
14. In
OEM Configuration Register 2,
the
MIC3001 address and look-up table offset can
be modified. The look-up table covers 128°C.
The temperature range for offset = 0 is 0° to
+127°C.) This range can be shifted down by
2x the value. The offset is set to. If offset = 15,
the temperature range becomes –30° to
+97°C.
15. In
OEM Configuration Register 0
window,
set
ENABLE/DISABLE
to
ENABLE.
16. On
Panels
list select
OEM CONFIG 3-4
and
select
EXTERNAL CALIBRATION
(default
setting),
LOS COMPARATOR ENABLE,
SHDN, RXLUT INPUT TEMPERATURE, and
RSOUT.
If needed, later set
ISTART
to a
different value to speed up the APC loop
during laser turn ON after a FAULT
occurrence. Close the window to return to
main window.
17. On
Panels
list, select
External Calibration.
Set all the
offsets
to 0 and
slopes
to 1. Set
RX_PWR(1)
to 1. These parameters might
need to be changed later to correct the
measured values (calibration). Return to the
main window.
September 2004
3
M9999-092304
hbwhelp@micrel.com
or (408) 955-1690
Micrel
TXRX_982_R1 Evaluation Board
18. On
Panels
list, select
Temperature
Compensation.
Load look-up tables for APC,
Modulation, Bias current Fault, and End-of-
Life from appropriate files. If no loading is
done, the default value 0 is used for all the
LUT. Return to the main window.
19. On
Panels
list, select
OEM settings.
Enter
the desired DAC values between 0 and 255
for the displayed parameters then select
SET
NEW.
Select
GET CURRENT
to make sure
that the set values are written into the
registers. Checking them can mask the faults.
Return to the main window.
20. On
Panels
list, select
User.
Check
APC0
in
the
USER CONTROL REGISTER
(default
setting). All the other parameters can be
checked later to verify their functionality.
Return to the main window.
21. On
Panels
list, select
Result.
The values of
the five monitored parameters as per SFF-
8472 are now displayed. Type the
alarm
and
warning
thresholds and select
SET NEW
LIMITS.
Select
GET CURRENT LIMITS
to
check that the set values are written into the
registers. Return to main window.
22. Set modulation current and bias current to get
the desired output power and extinction ratio
out of the laser. Use
OEM Settings
panel or
TX Setup
panel to do that:
a. In
OEM settings
window, set the bias
by entering a value from 10 to 255 in
APC SET POINT 0
box and
modulation by entering a value from
10 to 255 in MOD DAC setting box
followed by SET new.
b. In
TX calibration
window, set the bias
by entering a value from 10 to 255 in
APCO (DEC)
box and modulation by
entering a value from 10 to 255 in
MOD DAC setting box followed by
SET new.
After setting the new value for bias or modulation
current, toggle TXDISABLE/TXENABLE on the main
window.
23. At this step, there is no received power since
no signal is applied at the input of the receiver.
24. Adjust the VOA to bring the optical power to
the desired level at the input of the receiver.
Then connect the output of the VOA to the
input of the receiver using appropriate fiber
jumper.
25. If the installed receiver has RSSI signal, a
value (needs calibration) of the received
power should be displayed now.
26. On Panels list, select
TX Setup
to calibrate
the TX power. Measure the optical power at
the output of the VCSEL and enter the value
(in mW) in the
MEASURED TX POWER
box,
then select
CALIBRATE.
The monitored value
is adjusted to display the measured value by
automatically changing the slope set in the
EXTERNAL CALIBRATION
window.
Reconnect the VOA to the VCSEL and return
to the main window.
27. On
Panels
select
RX Calibration.
Measure
the input power to receiver at the output of the
VOA and enter the measured value (in mW) in
the
MEASURED RX POWER
box then select
CALIBRATE.
The monitored value is adjusted
to display the measured value by
automatically changing the slope set in the
EXTERNAL CALIBRATION
window.
Reconnect the VOA to the receiver and return
to the main window.
28. At this stage, the masked faults should be
unmasked and if there is a fault indication try
to find the cause for it and fix it to get the
transceiver running fault free and try to
measure the performance of the laser driver
and post amplifier.
September 2004
4
M9999-092304
hbwhelp@micrel.com
or (408) 955-1690
Micrel
TXRX_982_R1 Evaluation Board
Laser Response Tuning
Overshoot/Undershoot
The damping resistors R8 and R24 installed in series
with laser are 20 . This value might be tuned to a
higher value to minimize or suppress any overshoot
or undershoot on the optical signal out of the laser,
but keep in mind that higher value damping resistors
will lead to higher rise/fall time.
Laser's Package Inductance Compensation
A compensation network comprised of C9/R26 or
C9/R31 can be used to compensate for the laser
package inductance. R26 and R31 share the same
pad on the board, so only one at a time can be
installed. The values shown on the schematic are
used for the symbol only. C9 should be a few pF and
R26/R31 around 50 .
Performance
Figure 2 shows an optical eye diagram obtained with
a Fabry Perrot laser driven differentially.
(2.5Gbps), PRBS 2
23
–1, ER = 9.5
TIME (67ps/div.)
Figure 2. Optical Eye Diagram
September 2004
5
M9999-092304
hbwhelp@micrel.com
or (408) 955-1690
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