3.3 V Dual-Loop, 50 Mbps to 3.3 Gbps
Laser Diode Driver
ADN2870
Data Sheet
FEATURES
GENERAL DESCRIPTION
SFP/SFF MSA and SFF-8472 compliant
SFP reference design available
50 Mbps to 3.3 Gbps operation
Dual-loop control of average power and extinction ratio
Typical rise/fall time 60 ps
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
RoHS compliant
The ADN28701 laser diode driver is designed for advanced SFP
and SFF modules, using SFF-8472 digital diagnostics. The device
features dual-loop control of the average power and extinction
ratio, which automatically compensates for variations in laser
characteristics over temperature and aging. The laser needs
only to be calibrated at 25°C, eliminating the expensive and
time consuming temperature calibration. The ADN2870
supports single-rate operation from 50 Mbps to 3.3 Gbps or
multirate operation from 155 Mbps to 3.3 Gbps.
Average power and extinction ratios can be set with reference
voltages provided by a microcontroller DAC or by adjustable
resistors. The ADN2870 provides bias and modulation current
monitoring as well as fail alarms and automatic laser shutdown.
The device interfaces easily with the ADuC702x family of
MicroConverters® 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 available in a
space-saving 4 mm × 4 mm LFCSP specified over the −40°C to
+85°C temperature range.
APPLICATIONS
Multirate OC3 to OC48-FEC SFP/SFF modules
1×/2×/4× Fibre Channel SFP/SFF modules
LX-4 modules
DWDM/CWDM SFP modules
1GE SFP/SFF transceiver modules
1
Protected by U.S. Patent 6,414,974.
APPLICATIONS DIAGRAM
VCC
VCC
VCC
Tx_FAULT
VCC
L
Tx_FAIL
VCC
FAIL
ALS
IMODN
LASER
R
MPD
IMODP
DATAP
PAVSET
ANALOG DEVICES
MICROCONTROLLER
DAC
VCC
IBIAS
CONTROL
ADC
RZ
IBIAS
RPAV
1kΩ
CCBIAS
GND ERREF
ADN2870
1kΩ
ERSET
GND
IBMON
IMMON
VCC GND
PAVCAP
GND
1kΩ
GND
ERCAP
GND
470Ω
GND
04510-001
DAC
DATAN
100Ω
IMOD
PAVREF
Figure 1. Application Diagram Showing Microcontroller Interface
Rev. D
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Technical Support
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ADN2870
Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Theory of Operation ...................................................................... 11
Applications ...................................................................................... 1
Dual-Loop Control .................................................................... 11
General Description ......................................................................... 1
Control......................................................................................... 12
Applications Diagram ...................................................................... 1
Voltage Setpoint Calibration .................................................... 12
Revision History ............................................................................... 2
Resistor Setpoint Calibration ................................................... 14
Specifications .................................................................................... 3
IMPD Monitoring .......................................................................... 14
SFP Timing Specifications .............................................................. 5
Loop Bandwidth Selection ........................................................ 15
Absolute Maximum Ratings ........................................................... 6
Power Consumption .................................................................. 15
ESD Caution.................................................................................. 6
Automatic Laser Shutdown (Tx_Disable) .............................. 15
Pin Configuration and Function Descriptions ............................ 7
Bias and Modulation Monitor Currents ................................. 15
Typical Performance Characteristics ............................................. 8
Data Inputs.................................................................................. 15
Optical Waveforms ........................................................................ 10
Laser Diode Interfacing ............................................................. 16
Multirate Performance Using Low Cost Fabry Perot Tosa
NEC NX7315UA ........................................................................ 10
Alarms.......................................................................................... 17
Dual-Loop Performance Over Temperature Using DFB Tosa
SUMITOMO SLT2486 .............................................................. 10
Outline Dimensions ....................................................................... 18
Ordering Guide .......................................................................... 18
REVISION HISTORY
9/2020—Rev. C to Rev. D
Changed CP-24-2 to CP-24-14.................................... Throughout
Changes to Figure 5.......................................................................... 7
Updated Outline Dimensions ....................................................... 18
Changes to Ordering Guide .......................................................... 18
11/2017—Rev. B to Rev. C
Changed CP-24-14 to CP-24-2.................................... Throughout
Updated Outline Dimensions ....................................................... 18
Changes to Ordering Guide .......................................................... 18
8/2016—Rev. A to Rev. B
Changed CP-24-2 to CP-24-14.................................... Throughout
Changes to Table 4 ........................................................................... 7
Updated Outline Dimensions ....................................................... 18
Changes to Ordering Guide .......................................................... 18
3/2008—Rev. 0 to Rev. A
Changes to Features, General Description, and Figure 1 ............1
Changes to Table 3 ............................................................................6
Changes to Figure 5 ..........................................................................7
Reorganized Layout ..........................................................................8
Changes to Modulation Control Loop Section .......................... 11
Changes to Operation with Lasers with TemperatureDependent Nonlinearity of Laser LI Curve Section .................. 12
Changes to Voltage Setpoint Calibration Section ..................... 12
Changes to Figure 26 and Figure 27 ............................................ 13
Changes to Resistor Setpoint Calibration Section and IMPD
Monitoring Section ........................................................................ 14
Changes to Loop Bandwidth Selection Section ......................... 15
Changes to Laser Diode Interfacing Section, Figure 32, and
Figure 33 .......................................................................................... 16
Changes to Table 5 ......................................................................... 17
Updated Outline Dimensions ...................................................... 18
Changes to Ordering Guide .......................................................... 18
8/2004—Revision 0: Initial Version
Rev. D | Page 2 of 20
Data Sheet
ADN2870
SPECIFICATIONS
VCC = 3.0 V to 3.6 V. All specifications TMIN to TMAX, unless otherwise noted.1 Typical values as specified at 25°C.
Table 1.
Parameter
LASER BIAS CURRENT (IBIAS)
Output Current IBIAS
Compliance Voltage
IBIAS when ALS High
CCBIAS Compliance Voltage
MODULATION CURRENT (IMODP, IMODN)2
Output Current IMOD
Compliance Voltage
IMOD when ALS High
Rise Time2, 3
Fall Time2, 3
Random Jitter2, 3
Deterministic Jitter2, 3
Pulse Width Distortion2, 3
AVERAGE POWER SET (PAVSET)
Pin Capacitance
Voltage
Photodiode Monitor Current (Average Current)
EXTINCTION RATIO SET INPUT (ERSET)
Resistance Range
Voltage
AVERAGE POWER REFERENCE VOLTAGE INPUT (PAVREF)
Voltage Range
Photodiode Monitor Current (Average Current)
EXTINCTION RATIO REFERENCE VOLTAGE INPUT (ERREF)
Voltage Range
DATA INPUTS (DATAP, DATAN)4
V p-p (Differential)
Input Impedance (Single-Ended)
LOGIC INPUTS (ALS)
VIH
VIL
ALARM OUTPUT (FAIL)5
VOFF
Min
Max
Unit
100
VCC
0.2
mA
V
mA
V
90
VCC
0.05
104
96
1.1
35
30
mA
V
mA
ps
ps
ps
ps
ps
rms
20 mA < IMOD < 90 mA
20 mA < IMOD < 90 mA
80
1.35
1200
pF
V
μA
Resistor setpoint mode
25
1.35
kΩ
V
Resistor setpoint mode
Resistor setpoint mode
0.12
1
V
120
1000
μA
Voltage setpoint mode
(RPAV fixed at 1 kΩ)
Voltage setpoint mode
(RPAV fixed at 1 kΩ)
0.1
1
V
Voltage setpoint mode
(RERSET fixed at 1 kΩ)
2.4
V
Ω
ac-coupled
2
1.2
1.2
5
1.5
60
60
0.8
1.1
50
1.2
1.1
1.2
1.2
0.4
50
2
0.8
VON
IBMON, IMMON DIVISION RATIO
IBIAS/IBMON3
IBIAS/IBMON3
IBIAS/IBMON STABILITY3, 6
IMOD/IMMON
IBMON Compliance Voltage
Typ
85
92
V
V
>1.8
V
1.2 V
Alarm if > 1.7 V
Alarm if shorted to VCC (the alarm is
valid for voltage setting mode only)
Ignore
Under Voltage or Short to GND
Condition
Ignore
Alarm, if
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