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 [ MICREL SEMICONDUCTOR ]
