155Mbps to 622Mbps SFF/SFP Laser Driver with Extinction Ratio Control

Low-Cost 155Mbps Laser Driver with Extinction Ratio Control

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The 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) combines the features of automatic power control (APC), modulation compensation, and built-in thermal compensation. The APC loop maintains constant average optical power. Modulation compensation increases the modulation current in proportion to the bias current. These control loops, 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: Typical Application Circuit MAX3646: Typical Application Circuit Enlarge+

Key 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 Feature


  • 125Mbps Ethernet SFP, GBIC, and 1 x 9 Transceivers
  • Multirate OC-3 to OC-12 FEC Transceivers
Part NumberTarget Oper. Range
Data Rate
Data Rate
minmaxtypmaxmaxSee Notes
MAX3646 <11556223.347CML85100
$2.56 @1k
See All Laser Drivers (22)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX3646EVKIT: Evaluation Kit for the MAX3646

CAD Symbols and Footprints

  • MAX3646ETG+
  • MAX3646ETG+T
  • MAX3646ETG+TC86
  • Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

    Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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