Specifications

96 Control and Automation Solutions Guide
such as PLCs or industrial computers
(see the Programmable Logic Controllers
(PLCs) chapter). These transceivers and
computing systems manage the data
and feedback commands to open (or
not open) the door’s electric strike.
Some companies are running Internet
protocol to each door and providing
power by PoE (like the MAX5980 and
MAX5969D), which means that the
door only needs a single CAT5 cable.
Intrusion alarm systems include
glass-breakage detectors, laser beam
detectors, door open/shut sensors, and
occupancy sensors of various types such
as motion detectors that use infrared
(heat sensing), acoustics, magnetic
sensing, capacitive sensing, inductive
sensing, radar, or video image processing
to trigger alarms. Many of these sensors
produce a simple binary signal (e.g.,
intruder detected or not detected), and
the sensor modules simply either close
a relay contact or send a wireless signal
that an event has occurred (see the
Wireless Systems section in this chapter).
To completely free up a wireless sensor,
the batteries can be rechargeable types
and power can be supplied from energy
harvesting. The approaches are many,
including solar, acoustic, vibration, and
human energy such as pressing a light
switch pressing, pushing a door, walking
on a oor mat, etc. The MAX17710
energy-harvesting charger and protector
is ideal for managing these sources and
for charging and protecting the battery.
Once triggered by detected events,
alarm systems are either silent, to
catch trespassers in the act, or loud,
to scare o trespassers. Calls can be
automatically placed to security guards
or security companies contracted
by the building or home owners.
System control can be stand-alone or
part of the BAS. Older systems needed
many inputs because a star topology
was used. In this type of topology,
each sensor is separately wired into
the control panel. These systems have
mostly been replaced with “perimeter”
wired systems. In these systems, a single
cable encompasses the perimeter of the
area to be protected. Each sensor in the
system has a unique address on the bus.
Wireless links between the sensors
and the controller reduce the cabling
required. This lack of cabling makes
implementation of security systems
for existing homes and small buildings
easy. For more information, see the
Wireless Systems section in this chapter.
The output of the motion detector
can be used as part of an occupancy-
response system. During normal
business hours, the motion detector can
turn on lights as needed. After hours,
the motion detector serves as the sensor
portion of the security system. The BAS
can control which function prevails
based on the time of day and day of
the week. Also, because one device,
the motion detector, can be used for
two functions, occupancy-response
or sensing, installed costs are lower.
The sensors in the security system
can also sometimes be used to detect
re or smoke, and thus are often tied
into the re protection system.
Surveillance
Surveillance systems include cameras,
communications interfaces, video
recording systems, and display terminals.
These electronic systems require just
a few security guards to constantly
monitor entire facilities. Recorded
images are constantly improving in
quality and often serve as critical
pieces of evidence in trials. Improved
video quality, increased numbers of
cameras, and more recording time
are all goals of surveillance systems.
Maxim’s video products group has a
variety of products to address these
goals. For more information, go to:
www.maxim-ic.com/security.
Battery backup of security systems
can ensures security even in the
event of a power failure (or power
shuto by the intruder). Maxim has
a variety of battery management
products to address charging and
monitoring needs (go to: www.maxim-
ic.com/battery-management).
With networking capability built into
security systems, homes and buildings
can be monitored from anywhere in
the world with Internet access; alarms
can be sent to an Internet-connected
device such as the homeowner’s
or security guard’s smartphone.
Fire Alarm Systems
Fire alarm systems must detect res,
activate alarms, prevent false alarms
and notify response teams. In homes,
the minimum requirement by law is a
stand-alone battery-powered smoke
detector. However, many building
codes require more advanced systems
with smoke and heat detectors and
automatic sprinkler systems.
Fire safety systems can not only turn on
sprinklers where heat is detected, but
also, by sensing water ow in the pipes,
determine where the re is and report
this to related systems. If connected
to a BAS, this event can trigger the
system to automatically call the re
department and adjust HVAC duct
dampers and fan settings to prevent
the spread of smoke and re. These
automated systems greatly reduce
the time it takes a re department to
respond. The BAS can also command
elevators to return to the ground oor
and disregard requests for use.
RFID keycard and scanner for secure access control.