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PDF ADN2871 Data sheet ( Hoja de datos )
| Número de pieza | ADN2871 | |
| Descripción | Single-Loop Laser Diode Driver | |
| Fabricantes | Analog Devices | |
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FEATURES
SFP/SFF and SFF-8472 MSA-compliant
SFP reference design available
50 Mbps to 4.25 Gbps operation
Automatic average power control
Typical rise/fall time 60ps
Supports VCSEL, DFB, and FP lasers
Bias current range 2 mA to 100 mA
Modulation current range 5 mA to 90 mA
Laser fail alarm and automatic laser shutdown (ALS)
Bias and modulation current monitoring
3.3 V operation
4 mm × 4 mm LFCSP
Voltage setpoint control
Resistor setpoint control
Pin-compatible with ADN2870
APPLICATIONS
1×/2×/4× Fibre Channel SFP/SFF modules
Multirate OC3 to OC48-FEC SFP/SFF modules
LX-4 modules
DWDM/CWDM SFP modules
1GE SFP/SFF transceiver modules
VCSEL, DFB, and FP transmitters
3.3 V, 50 Mbps to 4.25 Gbps
Single-Loop Laser Diode Driver
ADN2871
GENERAL DESCRIPTION
The ADN2871 laser diode driver is designed for advanced
SFP and SFF modules, using SFF-8472 digital diagnostics. The
ADN2871 supports operation from 50 Mbps to 4.25 Gbps.
Average power and extinction ratio can be set with a voltage
provided by a microcontroller DAC or by a trimmable resistor
or digital potentiometer. The average power control loop is
implemented using feedback from a monitor photodiode. The
part provides bias and modulation current monitoring as well
as fail alarms and automatic laser shutdown. The device
interfaces easily with the ADI ADuC70xx family of micro-
converters and with the ADN289x family of limiting amplifiers
to make a complete SFP/SFF transceiver solution. An SFP
reference design is available. The product is pin-compatible with
the ADN2870 dual-loop LDD, allowing one PC board layout to
work with either device. For dual-loop applications, refer to the
ADN2870 data sheet.
The product is available in a space-saving 4 mm × 4 mm LFCSP
specified over the −40°C to +85°C temperature range.
Figure 1 shows an application diagram of the voltage setpoint
control with single-ended laser interface. Figure 36 shows a
differential laser interface.
VCC
Tx_DISABLE
Tx_FAULT
VCC
MPD
FAIL
ALS
VCC
IMODN
VCC
L
R
IMODP
VCC
LASER
DATAP
ADI
MICROCONTROLLER
DAC
ADC
PAVSET
PAVREF
RPAV
1kΩ
DAC
GND ERREF
ERSET
1kΩ
GND
CONTROL
×100
IMOD
100Ω
IBIAS
CCBIAS
ADN2871
VCC GND
IBMON
IMMON PAVCAP NC
GND
DATAN
1kΩ 470Ω
GND
GND
Figure 1. Application Diagram of Voltage Setpoint Control with Single-Ended Laser Interface
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 © 2005 Analog Devices, Inc. All rights reserved.
1 page  
ADN2871
SFP TIMING SPECIFICATIONS
Table 2.
Parameter
Symbol Min Typ
ALS Assert Time
t_off 1
ALS Negate Time1
t_on
0.15
Time to Initialize, Including
Reset of FAIL1
FAIL Assert Time
ALS to Reset Time
t_init
t_fault
t_reset
25
Max Unit Conditions/Comments
5 µs Time for the rising edge of ALS (TX_DISABLE) to when the bias
current falls below 10% of nominal.
0.4 ms Time for the falling edge of ALS to when the modulation current
rises above 90% of nominal.
275 ms From power-on or negation of FAIL using ALS.
100 µs
5 µs
Time to fault to FAIL on.
Time Tx_DISABLE must be held high to reset Tx_FAULT.
1 Guaranteed by design and characterization. Not production tested.
DATAP
DATAN
VSE
DATAP–DATAN
0V
V p-p DIFF = 2 × VSE
Figure 4. Signal Level Definition
SFP MODULE
VCC_Tx
1µH
0.1µF
0.1µF
3.3V
10µF
SFP HOST BOARD
Figure 5. Recommended SFP Supply
Rev. 0 | Page 5 of 20
5 Page 
PERFORMANCE CHARACTERISTICS
250
220
IBIAS = 80mA
190
IBIAS = 40mA
160
130
IBIAS = 20mA
100 IBIAS = 10mA
70
40
0 20 40 60 80 100
MODULATION CURRENT (mA)
Figure 20. Total Supply Current vs. Modulation Current
Total Supply Current = ICC + IBIAS + IMOD
120
115
110
105
100
95
90
85
80
–50 –30 –10 10 30 50 70
TEMPERATURE (°C)
90 110
Figure 21. IBIAS/IBMON Gain vs. Temperature, IBIAS = 20 mA
OC48 PRBS31
DATA TRANSMISSION
t_OFF LESS THAN 1µs
ALS
Figure 22. ALS Assert Time, 5 µs/div
ADN2871
60
55
50
45
40
35
30
25
20
–50 –30 –10 10 30 50 70
TEMPERATURE (°C)
90 110
Figure 23. Supply Current (ICC) vs. Temperature with ALS Asserted,
IBIAS = 20 mA
55
50
45
40
35
30
–50 –30 –10 10 30 50 70
TEMPERATURE (°C)
90 110
Figure 24. IMOD/IMMON Gain vs. Temperature, IMOD = 30 mA
ALS
TRANSMISSION
t_ON
Figure 25. ALS Negate Time, 50 µs/div
Rev. 0 | Page 11 of 20
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet ADN2871.PDF ] | |
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