AK2573/AK2573A pdf datasheet (

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.
All program and operational functions can be set
through the I2CTM compatible interface and stored in the
on-chip EEPROM.