The SY88904 is an integrated controller for the SY88902 Laser Driver and SY88903 Laser Receiver that provides power control and system interface functions for a complete module solution. The SY88904 is designed to provide the laser diode with an independent DC threshold current (IBIAS) source to assure optimum laser diode performance. It has special safety features which disable the currents to the laser diode if certain faults are detected in the module. The SY88904 also provides buffered Loss-of-Signal (LOS) output in open collector level. The device is designed for fast and accurate calibration of the laser diode as well as deriving the control signals for system integration. The SY88904 provides for delayed turn on of the laser diode on system start up, chatter-free Loss-of-Signal, Low VCC detect and laser diode over-current situations. Once the optimal operating point is determined and set for a specific laser diode, the threshold current (IBIAS) is designed to automatically compensate for laser diode aging and module temperature.