The X9520 combines three Digitally Controlled Potentiometers (DCPs), V1/Vcc Power-on Reset (POR) circuitry, two programmable voltage monitor inputs with software and hardware indicators, and integrated EEPROM with Block LockTM protection. All functions of the X9520 are accessed by an industry standard 2-Wire serial interface. Two of the DCPs of the X9520 may be utilized to control the bias and modulation currents of the laser diode in a Fiber Optic module. The third DCP may be used to set other various reference quantities, or as a coarse trim for one of the other two DCPs. The 2kbit integrated EEPROM may be used to store module definition data. The programmable POR circuit may be used to ensure that V1/Vcc is stable before power is applied to the laser diode/module. The programmable voltage monitors may be used for monitoring various module alarm levels. The features of the X9520 are ideally suited to simplifying the design of fiber optic modules which comply to the Gigabit Interface Converter (GBIC) specification. The integration of these functions into one package significantly reduces board area, cost and increases reliability of laser diode modules.