3.3 V Dual-Loop, 50 Mbps to 3.3 Gbps
Laser Diode Driver
ADN2870
FEATURES
GENERAL DESCRIPTION
SFP/SFF and SFF-8472 MSA-compliant
SFP reference design available
50 Mbps to 3.3 Gbps operation
Multirate 155 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
The ADN2870 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 need only
be calibrated at 25°C, eliminating the need for expensive and
time consuming temperature calibration. The ADN2870 supports
single-rate operation from 50 Mbps to 3.3 Gbps or multirate
from 155 Mbps to 3.3 Gbps.
Average power and extinction ratio can be set with a voltage
provided by a microcontroller DAC or by a trimmable resistor.
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 available in a space-
saving 4 mm ×4 mm LFCSP package specified over the −40°C to
+85°C temperature range.
4 mm × 4 mm LFCSP package
Voltage setpoint control
Resistor setpoint control
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
VCC
VCC
VCC
Tx_FAULT
VCC
L
Tx_FAIL
VCC
FAIL
ALS
IMODN
LASER
R
MPD
IMODP
DATAP
DATAN
PAVSET
PAVREF
ADI
MICROCONTROLLER
100Ω
IMOD
IBIAS
DAC
ADC
IBIAS
CONTROL
RPAV
1kΩ
GND
CCBIAS
ERREF
ERSET
DAC
ADN2870
1kΩ
GND
IBMON
IMMON
PAVCAP
ERCAP
VCC GND
GND
GND
1kΩ
GND
470Ω
GND
Figure 1. Application Diagram Showing Microcontroller Interface
Protected by US patent: US6414974
Rev. 0
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Specifications subject to change without notice. No license is granted by implication
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