3.3 V Dual-Loop, 50 Mbps to 3.3 Gbps
Laser Diode Driver

ADN2870


Rev. 0
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FEATURES
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
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
GENERAL DESCRIPTION
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.
04510-001
ADI
MICROCONTROLLER
Tx_FAULT
Tx_FAIL
CONTROL
PAVREF
PAVSET
ADN2870
RPAV
GND
DAC
DAC
VCC
MPD
ERREF
ERSET
GND
IMOD
DATAP
IMODP
DATAN
IBIAS
IMODN
IBMON IMMON
ALSFAIL
IBIAS
100Ω
CCBIAS
VCC
LASER
L
R
VCC
VCC
VCC
GND GND
PAVCAP
470Ω1kΩ
GND
GND
ERCAP
GND
1kΩ
1kΩ
ADC
VCC
Figure 1. Application Diagram Showing Microcontroller Interface
Protected by US patent: US6414974