74LCX04_ View Datasheet(PDF) - Micrel

Part Name

Description

Manufacturer

74LCX04_

TXRX_982_R1 Evaluation Board

Micrel 

Micrel

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.

TXRX_982_R1 Evaluation Board

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

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