GENERAL DESCRIPTION
Like the ADN2870, the ADN28721 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 be calibrated at 25°C, eliminating the need for expensive and time consuming temperature calibration. The ADN2872 supports single-rate operation from 50 Mbps to 3.3 Gbps, or multirate operation from 155 Mbps to 3.3 Gbps. With a new alarm scheme, this device avoids the shutdown issue caused by the system transient generated from various lasers.

FEATURES
   SFP/SFF and SFF-8472 MSA compliant
   SFP reference design available
   Any rate from 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

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