(1) LTR-502ALS
  - Digital Light Sensor + Proximity Sensor with LED driver.
  - Proximity Sensor detection distance, 5cm (typical).
  - ore flexible and less complex optical window design.
(2) LTR-505ALS
  - Digital Light Sensor + Proximity Sensor with LED driver and IR LED.
  - Fully integrated solution.
  - Proximity Sensor detection distance, 2.5 cm (typical).

Analog encoders provide a linear direct output whereas digital encoders noprmally provide a step coun function and thus encompasses an AD converter.

The key types of photo-interruptors includes actuator, slot and reflective.

A reflective phtot-interruptor has both the emitter and detctor housed on the same side of the sensor. The emitter send off infrared light which bouces off the object surface to be picked up by the detector. Typically reflective photo-interruptors are used in industrial applications and productions lines as counters. Increasingly small SMD reflective sensors are used in mobile devices as proximity sensors.

(1) Analog : 
  - Additional signal processing circuitries required including a dedicated ADC
  - Small dynamic range, typically up to 1k lux as photodiode current will saturate under outdoor application
  - Poor linearity for photo-transistors type of sensors
  - No shutdown mode
(2) Digital :
  - No additional signal processing circuitries required. Device includes I-V conversion / amplification / 50/60Hz rejection / temperature compensation circuitries.
  - Smaller PCB space / Lower total cost
  - No dedicated interface circuit required. Interface is via I2C bus and the microcontroller can connect up to 255 slave devices in parallel.
  - Wide dynamic range up to 65k lux / 100k lux which is suited for both indoor and outdoor applications
  - Shutdown mode / Interrupt / Persist feature

An actuator interruptor has an external arm in which the object of detection comes into contact with. The arm when contacted will move to block the light path between the emitter and detector, triggering a detection output. Actuator photo-interruptors are commonly used in slot and coin machines.

LITEON encoders are used in a wide range of applications. It is most widely used in printers for functions like, paper feed and ink head positioning.

An encoder is a device that converts information from one format to another. LITEON's encoder typically converts the number of revolution of a code wheel or the distance moved by a code strip to a digital count.

A photo-interruptor is a sensor that uses light path to detect the prescence of an object and gives a signal output when an object is detected. Typically in has an emmitter and detector put together in a housing.

IrDA is using infrared technology. Not affected by RF regulations.