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.
Key Features
Applications/Uses
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
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