Board Description. Quick Start optical operation. Description board se

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Board Description. Quick Start optical operation. Description board settings. General Notes. Component List. Schematic board. Board Layout Information Silkscreen Image board Optical Eyes
TECHNICAL NOTE TN009
ADN2841 OPTICAL EVALUATION
This Technical Note describes ADN2841 laser diode driver Rev. evaluation kit. evaluation demonstration board that provides optical evaluation ADN2841. This document describes configure board order operate part optically. document contains following information:
Board Description:
ADN2841 dual loop 155Mbs 2.7Gbps laser diode driver. board optical configuration, suitable laser diode driver must soldered onto board. monitor photo diode, MPD, current into ADN2841 control average power extinction ratio. ADN2841 uses automatic power control, APC, maintain constant average power over time temperature. ADN2841 uses closed loop extinction ratio control allow optimum setting extinction ratio every device. This board configured lasers Minidil packages only. LEDs Power Supply, DEGRADE, FAIL made available monitoring purposes. Power evaluation circuitry only!
Quick Start Optical Operation:
ensure proper operation optical configuration, verify following: Jumpers connected Jumpers connected input data clocked necessary enable clock select (CLKSEL). CLKSEL enabled connecting clock inputs used, input data latched, connect power supply diode protected ensure device damaged power supply accidently connected. user connect Jumper (short circuit) power board applying POWER input SMA, Jumper connected then user should make power supply sufficiently negative enure that supply -5V. actual supply measured anode
REV.
Technology Way, P.O. 02062-9106, U.S.A. Tel: Fax: 617/326-8703 9106, Norwood. 617/329-4700 Information furnished Analog Devices believed accurate reliable. However, responsibility assumed Analog Devices use, infringements patents other rights third parties which result from use. license granted implication otherwise under patent patent rights Analog Devices.
REV. Oct. 2001
TECHNICAL NOTE -HSN TN009
ADN2841 EVALUATION
Apply differential signal, typically 500mV, (DATAN DATAP). Single ended operation result degraded clock select enabled apply differential clock signal, typically 500mV, (CLKN CLKP). optical switching characteristics ADN2841 observed using digital communications analyser which optical input channel with required bandwidth. bias modulation currents also monitored observing Ibmon Immon respectively. Ibmon Immon both 1:100 ratio Ibias Imod. Both terminated with resistors viewed Test Points using voltmeter oscilloscope. establish desired average power extinction ratio user should follow below procedure: With power supply turned adjust potentiometers (ERSET) (PSET) approx 20k. With evaluation board powered reduce value potentiometer establish desired average optical power. Potentiometer then reduced value increase modulation current, hence increase extinction ratio. bias current will decrease modulation current increases. bias modulation currents monitored using IBMON IMMON. When adjusting extinction ratio user should allow adequate time settle. allowable resistance range Power Input (PSET), Extinction Ratio Input (ERSET), Alarm (ASET) between 1Kohm 25Kohm. Resistors R31-R33 ensure that resistance these nodes never falls below minimum allowable value. node resistances increase above 25Kohm ADN2841 operate within specifications.
REV. 2001
TECHNICAL NOTE -HSN TN009
ADN2841 EVALUATION
Description Board Settings: COMPONENT NAME POWER IDTONE CLKN CLKP DATAP DATAN IMPDMON IMPDMON2 IBMON IMMON ASET POTENTIOMETER ERSET POTENTIOMETER PSET POTENTIOMETER FUNCTION power input board Idtone input. Clkn input. Clkp input. Datap input. Datan input. IMPD Current Mirror Monitor MPD2 Current Mirror Monitor Bias Current Mirror Monitor Modulation Current Mirror Monitor Adjusts bias current threshold disable fail alarms. Adjusts slope efficiency. Adjusts current thus average power. Jumper bypass supply protection diode. Jumper LBWSET Jumper exercise Jumper CLKSEL Jumper IDTONE
REV. 2001
TECHNICAL NOTE -HSN TN009
ADN2841 EVALUATION
COMPONENT R19, R20, C4-C12, C16-C18 C13, R10, R15, R16, R17, R31-R33 R11, R12, R13, R25*, R26, R27*, R28*, K1-K5 J3-J7, DESCRIPTION trim potentiometer Supply Protection Diode (IN4001) LEDs 10nF capacitor 220uF capacitor capacitor (Loop Bandwidth Setting) Transistor (SOT23) 22uF resistor. resistor Resistor resistor resistor. resistor resistor. resistor. resistor header jumper sockets connector. ADN2841 Laser Diode supplied Analog Devices 10µH inductor
*Signifies components which populated
REV. 2001
TECHNICAL NOTE -HSN TN009
ADN2841 EVALUATION
Figure Schematic Board
REV. 2001
TECHNICAL NOTE -HSN TN009
ADN2841 EVALUATION
BOARD LAYOUT
Figure Component Side
Figure Ground Plane
Figure Power Plane
Figure Solder Side
REV. 2001
TECHNICAL NOTE -HSN TN009
ADN2841 EVALUATION
Figure Silkscreen Image
Figure Unfiltered 2.5Gbs Optical Eye. Average Power -3dBm, Extinction Ratio 9.5dB. obtained using Mitsubishi FU-445-SDF.
Figure Filtered 2.5Gbs Optical Eye. Average Power -3dBm, Extinction Ratio 9dB. obtained using Mitsubishi FU-445-SDF
REV. 2001
TECHNICAL NOTE -HSN TN009

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