VSC7939

www.DataSheet4U.com VITESSE SEMICONDUCTOR CORPORATION Preliminary Data Sheet VSC7939 Features Power Supply: 3.3V or 5V ±5% AC-Coupled to Laser Diode SONET/SDH 3.125Gb/s Laser Diode Driver with Automatic Power Control Applications SONET/SDH at 622Mb/s, 1.244Gb/s, 2.488Gb/s, 3.125Gb/s Full-Speed Fibre Channel (1.062Gb/s) Programmable Modulation Current: 5mA to 60mA Programmable Bias Current: 1mA to 100mA Enable /Disable Control Typical Rise/Fall Times of 60ps Automatic Optical Average Power Control Supply Current of 33mA at 3.3V General Description The VSC7939 is a single 3.3V or 5V supply laser diode driver specially designed for SONET/SDH applications up to 3.125Gb/s. External resistors set a wide range of bias and modulation currents for driving the laser. Data and clock inputs accept differential PECL signals. The automatic power control (APC) loop maintains a constant average optical power over temperature and lifetime. The dominant pole of the APC loop can be controlled with an external capacitor. Other features include enable/disable control, short-circuit protection for the modulation and bias inputs, short rise and fall times, programmable slow-start circuit to set laser turn-on delay, and failure-monitor output to indicate when the APC loop is unable to maintain the average optical power. The VSC7939 is available in die form or in a 32-pin TQFP package. Block Diagram 3.3V Operation LP IOUT+ IOUTMUX DATA+ DATACLK+ CLKD SET VCC LATCH CD CF...