Polymeric Positive Temperature Coefficient
(PPTC) Resettable Devices
Technology and Application Guide
Bolivar Drive * P.O. Box 547 * Bradford, PA. 16701 * USA * 814-362-5536 * 814-362-8883 * www.koaspeer.com
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FEATURES AND BENEFITS OF
SmartFuseTM Devices
Features:
• Remotely resettable
• Board testable
• Low resistance
• Faster time to trip
• Surface Mountable
• Solid State
Benefits:
• Improve system reliability
• Lower warranty cost & service
• Reduce system downtime
• Lower voltage drop
• Provide effective protection
• Can be used on PCB
• Ruggedness prevents breakage during manufacturing and
shipment
• Shock & vibration resistance eliminates need for calibration
Bolivar Drive * P.O. Box 547 * Bradford, PA. 16701 * USA * 814-362-5536 * 814-362-8883 * www.koaspeer.com
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Technology
SmartFuseTM PPTC Resettable Devices
When you look for solutions to meet your
overcurrent protection requirements, you can now
count on SmartFuse T M Polymeric Positive
Temperature Coefficient (PPTC) resettable devices
from KOA Speer Electronics, Inc.
Like fuses, SmartFuseTM PPTC Resettable Devices
interrupt the flow of dangerously high current during
fault conditions. But unlike fuses, SmartFusesT M
PPTC Resettable Devices automatically reset after
the fault is cleared and power to the circuit is
removed, thereby eliminating warranty cost and
service calls due to blown fuses. This performance
advantage over fuses is directly translated into higher
product quality and reliability and better customer
satisfaction.
Based on conductive polymer composite technology
which involves the blending of specially formulated
polymers with various conductive materials,
SmartFuseTM PPTC Resettable Devices protect
customer s products from damaged caused by
overcurrent conditions such as short circuit and
overload. These devices provide overcurrent
temperature and thus reducing the currents in the
circuits, being protected, to low levels when
overcurrent conditions develop. When power is
removed, the devices cool down and their resistance
returns to normal level, permitting the protected
circuit to be ready for operating again.
Log
R
Oh
ms
10
7
10
6
10
5
10
4
10
3
10
2
10
1
10
0
0
20
40
60
80
100
120
140
How SmartFuseTM PPTC Resettable
Devices Work
The conductive polymer composites from which
SmartFuse T M PPTC Resettable Devices are made
consist of one or more semi-crystalline polymers
(formed by crystalline and amorphous phases)
dispersed with various conductive particles such as
carbon black. Under normal conditions, the conductive
particles with the conductive polymer composite form
conductive chains through the amorphous phase of the
matrix polymer. As a result, the resistance of the
SmartFuseTM PPTC Resettable Device is much lower
than the resistance of the rest of the circuit. Therefore,
the device has little or no effect on the normal
operation of the protected circuit. When fault
condition develops excessive current flows through the
device and the resulting increase of joule heating (I2R)
raises the device s internal temperature quickly. When
the temperature reaches the melting temperature of the
matrix polymer, the crystalline phase is melted and
becomes amorphous. The volume of amorphous phase
increases, which causes the conductive chains to
separate. As the distance between the conductive
particle increases, the resistance of SmartFuseTM PPTC
Resettable Devices increases rapidly and sharply which
is called tripping the device. The increase in
resistance reduces the current in the protected circuit to
a very low level.
At this tripped state, the SmartFuseTM PPTC Resettable
Devices will remain at its high-resistance-state as long
as the protected circuit remains powered, providing
continuos protection. Once the fault is cleared and
power is removed, the material cools down and the
matrix polymer undergoes a re-crystallization process.
As it does so, the amorphous particles re-establish their
conductive chains within the shrunk amorphous phase.
As a result of this phase transition, the resistance of the
SmartFuseTM PPTC Resettable Device is lowered to its
normal value, permitting the protected circuit to
function normally again without the user needing to
replace a board level component.
160
Temperature C
Bolivar Drive * P.O. Box 547 * Bradford, PA. 16701 * USA * 814-362-5536 * 814-362-8883 * www.koaspeer.com
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Amorphous
Phase
Crystalline
Phase
Nonconductive
Tripping
Conductive
Chains
Chains
Resetting
Amorphous
Phase
Normal
State
- ambient temp.
- conductive chains
- low resistance
Tripped
State
- high temp.
- chains disrupted
- high resistance
APPLICATIONS
Unlike fuses, which must be replaced after working , the SmartFuse TM PPTC Resettable Devices resets automatically
once the fault is cleared and the power is removed. The benefits include lower manufacturer s warrant cost, fewer service
calls, higher product reliability and increased customer satisfaction. SmartFuseTM PPTC Resettable Devices can be used
almost everywhere there is a power source and a load. There are many applications for SmartFuseTM PPTC Resettable
Devices in a variety of markets and industries.
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Audio Equipment
Automotive Electronics
Automotive Harness Protection
Computers and Peripherals
Desktop Computers
Notebook Computers
Personal Digital Assistants (PDAs)
Point-of-Sale (POS) Equipment
Primary and Secondary Batteries
Security and Fire Alarm Systems
Small & Medium Motors
Telecommunications Equipment
Toys
Transformers
Bolivar Drive * P.O. Box 547 * Bradford, PA. 16701 * USA * 814-362-5536 * 814-362-8883 * www.koaspeer.com
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COMPUTER and PERIPHERALS
As increasing number of peripheral devices are being added to the computer, the designs of the computer system
become more and more complex. Overcurrent protection for the computers and peripheral devices has become
increasingly important due to the greater likelihood of occurring of electrical faults.
SmartFuseTM PPTC Resettable Devices being resettable and packaged in standard form factors, are ideal overcurrent
protection solutions for any computers and peripheral devices, including:
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Keyboard and Mouse Ports
Disk Drives
PC Cards
Ethernet Cards
Audio and Video Cards
Printers and Scanners
Universal Series Bus (USB) Hubs & Ports
Cable Modems
Digital Cameras
DVD-ROMS
Monitors
Personal Digital Assistants (PDAs)
IEE 1394 Ports
Chargers
Relevant Products:
Surface Mount Package
SFSMC Series size: 1812 mils
SFmSMC Series size: 1210 mils
Radial Leaded Package
SFRL60 Series
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Features
Surface mount chip package
Fast tripping resettable circuit protection
Packaging for automated assembly
Reduced component size and resistance
Features
Radial Leaded Package
Cured, flame retardant epoxy polymer insulating
material meets UL 94V0 requirements
Bulk packaging, tape & reel & ammo-pack available
on most models
Voltage rating: 60V for RL60
Bolivar Drive * P.O. Box 547 * Bradford, PA. 16701 * USA * 814-362-5536 * 814-362-8883 * www.koaspeer.com
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BATTERY SYSTEMS
Cellular phones, notebook computers, power tools, camcorders and battery-powered toys and other portable
electronics are important parts of our life. All of these products rely on rechargeable batteries that pack considerable
electrical energy. Short circuit across the battery terminals and overcharging of batteries can result in damage of
equipment, fires or severe burns if the batteries are not properly protected. SmartFuseTM PPTC Resettable Devices in
the disc, axial leaded and surface mount form factors are ideal solutions for:
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Lithium Battery Cells and Packs
Ni-Cad Battery Packs
NiMH Battery Packs
Li-ion Battery Cells and Packs
Relevant Products:
Axial Leaded Family
SFALST Series
SFALLT Series
SFALVT Series
Surface Mount Package
SFSMC Series size: 1812 mils
SFmSMC Series size: 1210 mils
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Features
Axial Leaded package
Fully compatible with current industry standards
Weldable nickel terminals
Very low internal resistance
Wide switching temperature range
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Features
Surface Mount Chip package
Fast tripping resettable circuit protection
Packaging for automated assembly
Reduced component size and resistance
Bolivar Drive * P.O. Box 547 * Bradford, PA. 16701 * USA * 814-362-5536 * 814-362-8883 * www.koaspeer.com
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AUTOMOTIVE
As a result of consumers demands for more functional features and higher reliability, automotive manufacturers are
designing more electronic systems and powered accessories into a car. Each of these electronic systems and powered
accessories can be damaged by short circuit and overload conditions. Traditionally, fuses have been used as the primary
overcurrent protection solution in the cars.
However, due to the benefits of resettability, SmartFuseTM PPTC Resettable Devices have replaced these traditional
fuses and are being increasingly used to protect small and medium motors that drive the powered accessories, in-car
electronic systems and wire harness. The automotive applications for SmartFuseTM PPTC Resettable Devices include:
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Small and Medium motors in
• Power Windows
• Door Lock Actuators
• Power Seats
• Power Roofs
• Windshield Wipers
Car Audio Systems
Climate Sensors and Control
Wire Harness Protection
Cigarette Lighters
Relevant Products:
Radial Leaded Family
SFRL30 Series
SFRL60 Series
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Features
Radial Leaded package
Cured, flame retardant epoxy polymer
insulating materials meet UL 94V0
requirements
Bulk packaging, tape & reel and ammo-pack
available on most models
Voltage rating: 30V for RL30
Voltage rating: 60V for RL60
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Features
Surface mount chip package
Fast tripping resettable circuit protection
Packaging for automated assembly
Reduced component size and resistance
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Surface Mount Package
SMSMC Series size: 1812 mil
SFmSMC Series size: 1210
GENERAL ELECTRONICS
Bolivar Drive * P.O. Box 547 * Bradford, PA. 16701 * USA * 814-362-5536 * 814-362-8883 * www.koaspeer.com
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Within the general electronics market the SmartFuseTM PPTC Resettable Devices find applications in the
following equipment:
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Loud Speakers
Security and Fire Alarm Systems
Medical Electronics
Transformers
Test & Measurement Equipment
Satellite Video Receivers
Point-of-Sales (POS) Equipment
Motors
Battery Chargers
Industrial Controls
Relevant Products:
Surface Mount Package
SMSMC Series size: 1812 mil
SFmSMC Series size: 1210
Radial Leaded Package
SFRL30 Series
SFRL60 Series
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•
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•
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Features
Surface mount chip package
Fast tripping resettable circuit protection
Packaging for automated assembly
Reduced component size and resistance
Features
Radial Leaded package
Cured, flame retardant epoxy polymer
insulating materials meet UL 94V0
requirements
Bulk packaging, tape & reel and ammo-pack
available on most models
Voltage rating: 30V for RL30
Voltage rating: 60V for RL60
Bolivar Drive * P.O. Box 547 * Bradford, PA. 16701 * USA * 814-362-5536 * 814-362-8883 * www.koaspeer.com
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