The AK2572 enables to keep the optical power of the direct modulation LD (Laser Diode) constant by the APC (Automatic Power Control) circuit. It consists of a current programming function (APC_FF) responding to the temperature characteristics of each LD, and a Digital feedback function (APC_FB) to adjust the LD current based on the monitoring PD (Photo Diode) current. The AK2572 is also applicable to the Burst mode transmission. The device equips a Power leveling function to switch a temperature compensation programming data by either Hardware pin control or Register setting. The On-chip EEPROM (Non-volatile memory) allows to adjust and to keep the individual setting data for each LD characteristics via 2-wire Digital interface after being assembled into sub-system. As 1k bits User Area is allocated in the EEPROM, which supports the ID field of the SFP specification, a proper operation required for the SFP module is realized by using the TXFAULT function.