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