3.3 V, 50 Mbps to 4.25 Gbps,

Single-Loop, Laser Diode Driver

ADN2871

Rev. A

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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 60 ps

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

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 (ALS). The device

interfaces easily with the Analog Devices, Inc. ADuC70xx

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

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.

ADI

MICROCONTROLLER

Tx_DISABLE

Tx_FAULT

CONTROL

PAVREF

PAVSET

ADN2871

RPAV

GND

DAC

DAC

MPD

ERREF

ERSET

GND

IMOD

DATAP

IMODP

DATAN

IMODN

IBMON

IMMON

ALS

FAIL

IBIAS

100Ω

CCBIAS

LASER

L

R

GND

GND

PAVCAP

470Ω

1kΩ

GND

GND

NC

1kΩ

1kΩ

ADC

×100

Figure 1. Application Diagram of Voltage Setpoint Control with a Single-Ended Laser Interface