DS1875

Rev 1; 10/08 www.DataSheet4U.com PON Triplexer and SFP Controller General Description The DS1875 controls and monitors all functions for burstmode 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. 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 TemperatureIndexed LUT ♦ PWM Controller ♦ Boost or Buck Mode ♦ Boost Mode: Uses Optional External Components, Up to 90V Bias Generation ♦ 131kHz, 262kHz, 525kHz, or 1050kHz SelectableSwitching Frequency ♦ APD Over...