The ADN2525 laser diode driver is designed for direct modulation of packaged laser diodes having a differential resistance ranging from 5 to 50 . The active back-termination technique provides excellent matching with the output transmission lines while reducing the power dissipation in the output stage. The back-termination in the ADN2525 absorbs signal reflections from the TOSA end of the output transmission lines, enabling excellent optical eye quality to be achieved even when the TOSA end of the output transmission lines is significantly misterminated. The small package provides the optimum solution for compact modules where laser diodes are packaged in low pin-count optical subassemblies. The modulation and bias currents are programmable via the MSET and BSET control pins. By driving these pins with control voltages, the user has the flexibility to implement various average power and extinction ratio control schemes, including closed-loop control and look-up tables. The automatic laser shutdown feature allows the user to turn on/off the bias and modulation currents by driving the ALS pin with the proper logic levels.