The DS1862 is a closed-loop laser-driver control IC with built-in digital diagnostics designed for XFP MSA. The laser control function incorporates average power con- trol (APC) and allows extinction ratio control though a temperature indexed look-up table (LUT). The DS1862 monitors up to seven analog inputs, including tempera- ture and monitor diode (MD) current, which are used to regulate the laser bias current and extinction ratio. Warning and alarm thresholds can be programmed to generate an interrupt if monitored signals exceed toler- ance. Calibration is also provided internally using inde- pendent gain and offset scaling registers for each of the monitored analog signals. Settings such as pro- grammed calibration data are stored in password-pro- tected EEPROM memory. Programming is accomplished through an I2C-compatible interface, which can also be used to access diagnostic functionality.