AK2571 pdf datasheet (WDM Lase

The AK2571 is a single-chip solution for WDM Laser Diode Module applications. It integrates both ATC (Auto Temperature Control) and APC (Auto Power Control) functions in a small 64-pin LQFP or bare die package..
The ATC function of the AK2571 detects the LD module temperature via an external thermister and uses the PID algorithm to control the Thermo-Electric Cooler (TEC). This provides +/- 0.1°C stabilization.. A customer can program the appropriate PID parameters into the internal EEPROM , thereby providing compensation characteristics for each Laser Diode. TEC control is handled through either PWM or Analog current control through I-DAC4. These are easily selected by an EEPROM (Register) setting.
The APC has two functions. The first function is to compensate for Laser Diode power decreases caused by aging. The other function is to compensate for temperature variations of AK2571 and external components (current amplifier or driver circuits) which may be affected by ambient temperature within the LDM. The AK2571 does this by controlling BIAS and modulation current according to the look up table in EEPROM .
The AK2571 has every alarm needed for WDM modules (Loss of power, Over current, Temperature etc.). There is a dithering function for modulation current that improves the extinction ratio for long distance transmissions.
Also, parameter and compensation data can be stored for four wavelengths. If a customer uses a tunable laser diode, it is very easy to change the wavelength by pin control