Features: Single +3.3V Power Supply
47mA Power-Supply Current
85mA Modulation Current
100mA Bias Current
Automatic Power Control (APC)
Modulation Compensation
On-Chip Temperature Compensation
Self-Biased Inputs for AC-Coupling
Ground-Referenced Current Monitors
Laser Shutdown and Alarm Outputs
Enable Control and Laser Safety FeatureApplicationMultirate OC-3 to OC-12 FEC Transceivers
125Mbps Ethernet SFP, GBIC, and 1 x 9
TransceiversPinout
SpecificationsSupply Voltage VCC...........................................................-0.5V to +6.0V
IN+, IN-, TX_DISABLE, TX_FAULT, SHUTDOWN, BC_MON, PC_MON, APCFILT1, APCFILT2, MD, TH_TEMP, MODTCOMP, MODBCOMP,MODSET, and APCSET Voltage.............-0.5V to (VCC + 0.5V)
OUT+, OUT-, BIAS Current............................................-20mA to +150mA
Continuous Power Dissipation (TA = +85°C)
24-Pin QFN (derate 20.8mW/°C above +85°C) .......................1805mW
Operating Junction Temperature Range......................-55°C to +150°C
Storage Temperature Range ......................................-55°C to +150°C
DescriptionThe MAX3646 is a +3.3V laser driver designed for multirate transceiver modules with data rates from 155Mbps to 622Mbps. Lasers can be DC-coupled to the MAX3646 for reduced component count and ease of multirate operation.
Laser extinction ratio control (ERC) of MAX3646 combines the features of automatic power control (APC), modulation compensation, and built-in thermal compensation. The APC loop maintains constant average optical power. odulation compensation increases the modulation current in proportion to the bias current. These control loops of MAX3646, combined with thermal compensation, maintain a constant optical extinction ratio over temperature and lifetime.
The MAX3646 accepts differential data input signals. The wide 5mA to 60mA (up to 85mA AC-coupled) modulation current range and up to 100mA bias current range, make the MAX3646 ideal for driving FP/DFB lasers in fiber optic modules. External resistors set the required laser current levels. The MAX3646 provides transmit disable control (TX_DISABLE), single-point fault tolerance, bias-current monitoring, and photocurrent monitoring. The device also offers a latched failure output (TX_FAULT) to indicate faults, such as when the APC loop is no longer able to maintain the average optical power at the required level. The MAX3646 is compliant with the SFF-8472 transmitter diagnostic and SFP MSA timing requirements.
The MAX3646 is offered in a 4mm x 4mm, 24-pin thin QFN package and operates over the extended -40°C to +85°C temperature range.
MAX3646 Data Sheet
