PON Triplexer and SFP Controller

Industry's Next-Generation PON/SFP Controller with APD Boost Converter for Fiber Optic Modules

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The DS1875 controls and monitors all functions for burst-mode transmitters, APD receivers, and video receivers. It also includes a power-supply controller for APD bias generation, and provides all SFF-8472 diagnostic and monitoring functionality. The combined solution of the DS1875 and the MAX3643 laser driver provides APC loop, modulation current control, and eye safety functionality. Ten ADC channels monitor VCC, temperature (both internal signals), and eight external monitor inputs (MON1–MON8) that can be used to meet transmitter, digital receiver, video receiver, and APD receiver-signal monitoring requirements. Four total DAC outputs are available. A PWM controller with feedback and compensation pins can be used to generate the bias for an APD or as a step-down converter. Five I/O pins allow additional monitoring and configuration.
DS1875: Typical Operating Circuit DS1875: Typical Operating Circuit Enlarge+

Key Features

  • Meets All PON Burst-Timing Requirements for Burst-Mode Operation
  • Laser Bias Controlled by APC Loop and Temperature Lookup Table (LUT)
  • Laser Modulation Controlled by Temperature LUT
  • Six Total DACs: Four External, Two Internal
  • Two 8-Bit DACs, One of Which is Optionally Controlled by MON4 Voltage
  • Internal 8-Bit DAC Controlled by a Temperature-Indexed LUT
  • PWM Controller
  • Boost or Buck Mode
  • Boost Mode: Uses Optional External Components, Up to 90V Bias Generation
  • 131kHz, 262kHz, 525kHz, or 1050kHz Selectable-Switching Frequency
  • APD Overcurrent Protection Using Optional Fast Shutdown
  • 10 Analog Monitor Channels: Temperature, VCC, Eight Monitors
  • Internal, Factory-Calibrated Temperature Sensor
  • RSSI with 29dB Electrical Dynamic
  • Five I/O Pins for Additional Control and Monitoring Functions, Four of Which are Either Digital I/O or Analog Monitors
  • Comprehensive Fault-Measurement System with Maskable Laser Shutdown Capability
  • Two-Level Password Access to Protect Calibration Data
  • 120 Bytes of Password-1 Protected Memory
  • 128 Bytes of Password-2 Protected Memory in Main Device Address
  • 256 Additional Bytes Located at A0h Slave Address
  • I²C-Compatible Interface for Calibration and Monitoring
  • 2.85V to 3.9V Operating Voltage Range
  • -40°C to +95°C Operating Temperature Range
  • 38-Pin TQFN (5mm x 7mm) Package


  • APD Controller
  • BPON, GPON, or EPON Optical Triplexers
  • SFF, SFP, and SFP+ Transceiver Modules
Product Reliability Reports: DS1875.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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