General Description
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.

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

Applications
    SFF, SFP, and SFP+ Transceiver Modules