The MAX3850 is a +3.3V DC-coupled laser driver for SDH/SONET applications up to 2.7Gbps. The device accepts differential data and clock inputs and provides bias and modulation currents for driving a laser. If a clock signal is available, a synchronizing input latch can be used to reduce jitter. An automatic power-control (APC) feedback loop is incorporated to maintain a constant average optical power over temperature and lifetime. The wide modulation current range of 5mA to 60mA (up to 80mA AC-coupled) and bias current of 1mA to 100mA are easy to program, making this product ideal for SDH/SONET applications. The MAX3850 also provides laser current-enable control, two current monitors that are directly proportional to the laser bias and modulation currents, and a failure-monitor output to indicate when the APC loop is unable to maintain the average optical power. Designed to be DC-coupled to the laser with a supply voltage of only 3.3V, the MAX3850 greatly simplifies interface requirements. The MAX3850 is available in a small 32-pin QFN package as well as dice.