3.3 V, 50 Mbps to 4.25 Gbps,
Single-Loop, Laser Diode Driver
SFP/SFF and SFF-8472 MSA compliant
SFP reference design available
50 Mbps to 4.25 Gbps operation
Automatic average power control
Typical 60 ps output rise/fall time
VCSEL, DFB, and FP laser support
www.DataSheeBt4iaUs.ccoumrrent range: from 2 mA to 100 mA
Modulation current range: from 5 mA to 90 mA
Laser fail alarm and automatic laser shutdown (ALS)
Bias and modulation current monitoring
Voltage setpoint control
Resistor setpoint control
3.3 V supply
24-lead 4 mm × 4 mm LFCSP
Pin compatible with ADN2870
1×/2×/4× Fibre Channel SFP/SFF modules
Multirate OC3 to OC48-FEC SFP/SFF modules
DWDM/CWDM laser transmitters
HDTV (SMPTE family) laser transmitters
Like the ADN2870, the ADN2873 laser diode driver (LDD) is
designed for advanced SFP and SFF modules, using SFF-8472
digital diagnostics. The ADN2873 supports NRZ data
transmission operation from 50 Mbps up to 4.25 Gbps. With a
new alarm scheme, this device avoids the shutdown issue
caused by the system transient generated from various lasers.
The ADN2873 monitors the laser bias and modulation currents
and it provides fail alarms and ALS. Using setup voltages of a
microcontroller DAC or a trimmable resistor voltage divider,
the ADN2873 can set up a laser optical average output power and
extinction ratio. The optical average power control loop consists
of an optical feedback from a photodiode, the comparator, and a
status holder. The ADN2873 works easily with the Analog
Devices, Inc., ADuC7019/ADuC702x family of MicroConverter®
devices and with the ADN289x family of limiting amplifiers to
make a complete SFP/SFF transceiver chipset solution.
The ADN2873 is pin compatible with the ADN2870 dual-loop
LDD, allowing the same design to work with either device. For
dual-loop control applications, refer to the ADN2870 data sheet.
The product is available in a space-saving 24-lead, 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.
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