The AK2573A is a 1chip LDD (Laser Diode Driver) and an APC (Auto Power Control) for laser direct modulation application. It contains up to 156M LDD, programmable duty adjustment, BIAS and modulation currents, a digital feedback circuit, BIAS and modulation current monitors, failure alarms, I2CTM interface, an EEPROM for storing LD characteristics and user information, and TXFAULT detection for SFP application. The AK2573A has two APC functions; APC FF (Feed-forward) and APC FB (Feedback). APC FF supplies a programmed current in response to the temperature. APC FB provides a stable auto power control function with an internal digital feedback algorithm.