SFP+ Controller with Digital LDD Interface

Combination of DS1874 and MAX3798/MAX3799 Provides APC Loop, Current Control, and Complete SFF-8472 Functionality

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The DS1874 controls and monitors all functions for SFF, SFP, and SFP+ modules including all SFF-8472 functionality. The combination of the DS1874 with the MAX3798/MAX3799 laser driver/limiting amplifier provides APC loop, modulation current control, and eye safety functionality. The DS1874 continuously monitors for high output current, high bias current, and low and high transmit power to ensure that laser shutdown for eye safety requirements are met without adding external components. Six ADC channels monitor VCC, temperature, and four external monitor inputs (MON1–MON4) that can be used to meet all monitoring requirements. MON3 is differential with support for common mode to VCC. Two digital-to-analog (DAC) outputs with temperature-indexed lookup tables (LUTs) are available for additional monitoring and control functionality.
DS1874: Typical Operating Circuit DS1874: Typical Operating Circuit Enlarge+

Key Features

  • Meets All SFF-8472 Control and Monitoring Requirements
  • Laser Bias Controlled by APC Loop and Temperature LUT to Compensate for Tracking Error
  • Laser Modulation Controlled by Temperature LUT
  • Six Analog Monitor Channels: Temperature, VCC, MON1–MON4
    • MON1–MON4 Support Internal and External Calibration
    • Scalable Dynamic Range
    • Internal Direct-to-Digital Temperature Sensor
    • Alarm and Warning Flags for All Monitored Channels
  • Two 9-Bit Delta-Sigma Outputs with 36 Entry Temperature LUTs
  • Digital I/O Pins: Five Inputs, Five Outputs
  • Comprehensive Fault-Measurement System with Maskable Laser Shutdown Capability
  • Flexible, Two-Level Password Scheme Provides Three Levels of Security
  • 256 Additional Bytes Located at A0h Slave Address
  • I²C-Compatible Interface
  • 3-Wire Master to Communicate with the MAX3798/MAX3799 Laser Driver/Limiting Amplifier
  • +2.85V to +3.9V Operating Voltage Range
  • -40°C to +95°C Operating Temperature Range
  • 28-Pin TQFN (5mm x 5mm) Package


  • SFF, SFP, and SFP+ Transceiver Modules

Technical Documents

App Note 4638 DS1874 Quick Reference Guide
Product Reliability Reports: DS1874.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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Related Resources

Type ID Title
App Note 4638 DS1874 Quick Reference Guide
Type ID Title
Evaluation Board7285DS1874K Evaluation Kit for the DS1874