Specifications

64 Control and Automation Solutions Guide
Overview
Light sensing is used in a variety of
applications ranging from light dimming
based on ambient light intensity to
sophisticated industrial process-control
applications where critical decisions
are based on the sensor’s output.
Light may be sensed to monitor light
intensity, to use light in a feedback
loop, or to use light as a signal itself
as in indicators, trac signals, etc.
The main benet of using a light sensor
in a control loop is to provide immunity
against harsh environmental conditions.
Since light is not sensitive to vibration,
magnetic eld, or humidity, it provides
robust readings.
A mainstream type of light sensor
is an ambient light sensor that
measures the amount of visible light
in an environment. An ambient light
sensor should have a signal spectrum
that exactly matches the human eye
response, centered around 555nm,
which corresponds to green. Since
light intensities in the ambient
environment can vary over a broad
range, a light sensor with wide dynamic
range can be a key requirement.
For more specialized applications,
consider using a light sensor that
measures more than just the visible
spectrum and gives separate results
for dierent bands of wavelengths.
For these applications, an RGB color
sensor is a good solution. In some
cases, other wavelengths, including
infrared (IR), may be of interest. Maxim’s
MAX44006/8
*
RGB-clear-IR products
measure light over a broad spectrum
ranging from 400nm up to 1000nm
(near-ultra violet to near-infrared).
To enhance the reliability and accuracy
of the measurements, using digital light
sensors can provide many benets
including reduced board area, improved
noise performance, better sensitivity,
and lower costwhen compared
with discrete and analog solutions.
False readings in light measurements
can be caused by 50/60Hz icker noise
and DC IR noise. Well-designed digital
light sensors can overcome these issues
in their digital ltering sections.
Moreover, digital light sensors with
functions like interrupt and persistence
help to reduce the overhead on
microprocessors, allowing the system to
respond faster and consume less power.
Light Sensing
*Future product—contact the factory for availability.