11.3Gbps, Low-Power, AC-Coupled Laser Driver

182mW 10GBASE-LR Laser Driver Beats 1W SFP+ Spec

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The MAX3949 is a 3.3V, multirate, low-power laser diode driver designed for Ethernet, Fibre Channel, and SONET transmission systems at data rates up to 11.3Gbps. This device is optimized to drive a differential transmitter optical subassembly (TOSA) with a 25Ω flex circuit. The unique design of the output stage enables use of unmatched TOSAs.

The device receives differential AC-coupled signals with on-chip termination. It can deliver laser modulation currents of up to 85mA at an edge speed of 22ps (20% to 80%) into a 5Ω external differential load. The device is designed to have a high-bandwidth differential signal path with on-chip back termination resistors integrated into its outputs. An input equalization block can be activated to compensate for SFP+ host connector losses. The integrated bias circuit provides programmable laser bias currents up to 105mA. Both the laser bias current generator and the laser modulator can be disabled from a single pin.

The use of a 3-wire digital interface reduces the pin count while permitting adjustment of input equalization, polarity, output deemphasis, and modulation and bias currents without the need for external components. The device is available in a 3mm x 3mm, 16-pin TQFN package, and is specified for the -40°C to +95°C extended temperature range.
MAX3949: Functional Diagram MAX3949: Functional Diagram Enlarge+

Key Features

  • Low Power Consumption
  • Saves Board Space
    • Small 3mm x 3mm Package
  • Flexibility
    • Programmable Modulation Current Up to 85mA (5Ω Load)
    • Programmable Bias Current Up to 105mA
    • Programmable Input Equalization and Output Deemphasis
  • Safety
    • Supports SFF-8431 SFP+ MSA and SFF-8472 Digital Diagnostic
    • Integrated Eye Safety Features with Maskable Faults
    • Bias Current Monitor


  • 10GBASE-LR SFP+ Optical Transceivers
  • 10GBASE-LRM SFP+ Optical Transceivers
  • OC192-SR SFP+ SDH/SONET Transceivers

MAX3949EVKIT: Evaluation Kit for the MAX3949
Product Reliability Reports: MAX3949.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

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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