POLYFUSE®

POLYFUSE®

POLYFUSE®

Product catalog summary
Overview
The document is a technical guide for selecting POLYFUSE® Positive Temperature Coefficient (PTC) devices, which are used for overcurrent protection in electronic circuits. It covers various types of PTCs including surface mount, battery strap, and radial leaded types.
Specifications
The guide provides detailed specifications for different series of PTCs, including hold current (IHOLD), maximum voltage (VMAX), maximum fault current (IMAX), and operating temperature range. All series are RoHS compliant and lead-free. PTCs are available in amp ratings from 0.05A to 9.00A and maximum voltage ratings from 6V to 60V.
Selection Process
The selection process involves determining circuit parameters such as normal operating current, maximum circuit voltage, and ambient operating temperature. It includes verifying that the selected PTC meets these parameters and testing its suitability in the actual application. The process also involves selecting the appropriate form factor and applying thermal derating as necessary.
Applications
PTCs are used in personal computers, peripherals, cell phones, battery packs, industrial controls, and more. They are particularly useful in circuits that are not easily accessible for maintenance and are preferred over traditional fuses in applications where resettable protection is required.
PTC Characteristics
PTCs differ from traditional fuses in that they are resettable. They transition from a low-resistance to a high-resistance state in response to overcurrent, limiting the current flow without completely interrupting it. Key parameters include leakage current and fault current rating.
Comparison with Fuses
The document compares PTCs with traditional fuses, highlighting differences in reset capability, resistance, and time-current characteristics. PTCs are generally rated for lower voltages and currents compared to fuses and require more temperature derating.
Agency Approvals
PTCs are recognized under UL Standard 1434 for Thermistors and have approvals for use in Canada. Fuses have broader approvals, including UL/CSA/ANCE standards.
Temperature Derating
The guide includes temperature derating curves, showing that PTCs require more derating at higher temperatures compared to fuses.
Contact Information
Littelfuse provides contact details for technical assistance and sales across various regions including North America, Europe, Asia/Pacific, and Central and South America.
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Catalog excerpts

POLYFUSE®-1

that the circuit parameters do not exceed these ratings. Determine the following circuit operating parameters: 4. Verify that the ambient operating temperature within close proximity to the device is within its normal operating range. Thermally derate IHOLD and IMAX as necessary. See equation below. • Normal operating current – IHOLD • Maximum circuit voltage – VMAX • Maximum interrupt current – IMAX • Ambient operating temperature 2. Select the suitable form factor. 3. Compare the PTC data sheet ratings on littelfuse.com for VMAX and IMAX to ensure 5. Check that the trip time protects the circuit. 6. Verify that the post trip resistance (R1MAX) of the device is taken into account in the circuit design. 7. Independently test and evaluate the suitability and performance of the PTC in the actual application. Thermal derating factor RADIAL LEADED International Sales, Distribution and Engineering Facilities: Chip Size Hold Current (IHOLD) Max fault current (IMAX) Agency approval RoHS Compliant Operating Temperature Range World Headquarters Littelfuse, Inc. 800 E. Northwest Highway Des Plaines, IL 60016 USA www.littelfuse.com PTC Selection Table Series Name POLYFUSE® PTC SELECTION GUIDE COMPETITOR CROSS Tyco/Raychem Series Bourns Series North America • Birmingham, Michigan USA Des Plaines, Illinois USA and Irving, Texas USA Technical Assistance Phone: 800 999 9445 847 824 1188 Fax: 847 391 0459 Europe • Dünsen, Germany Phone: +49 4244 8190 Fax: +49 4244 819 139 • Munich, Germany Phone: +49 8955 27660 Fax: +49 8955 276 699 PTC Selection Table (cont.) BATTERY STRAP (AXIAL LEADED) Series Name Max fault current (IMAX) Chip Size Hold Current (IHOLD) Asia/Pacific • Hong Kong, China Phone: +852 2810 5099 Fax: +852 2810 5500 Operating Temperature Range Agency approval RoHS Compliant COMPETITOR CROSS Tyco/Raychem Series Amp Rating Max voltage Bourns Series FORM NO. EC327-E © November 2006, Littelfuse Inc. Printed in U.S.A. Specifications, descriptions and illustrative material in this literature are as accurate as known at the time of publication, but are subject to change without notice. Research and Manufacturing Facilities: • Arcola, Illinois USA • Des Plaines, Illinois USA • Dongguan, China • Dundalk, Ireland • Dünsen, Germany • Irving, Texas USA • Lipa City, Philippines • Matamoros, Mexico • Piedras Negras, Mexico • Suzhou, China • Swindon, England • Witten, Germany

 Open the catalog to page 1
POLYFUSE®-2

Recognized under the Component Program of Underwriters Laboratories to UL Standard 1434 for Thermistors. The devices have also been approved for use in Canada by Underwriters Laboratories. Approvals for fuses include Recognition under the Component Program of Underwriters Laboratories and the CSA Component Acceptance Program. In addition, many fuses are listed in accordance with UL/CSA/ANCE (Mexico) 248-14, Supplemental Fuses. ITU-T Recoomendations CPE (Customer Premises Equipment) The terminology used for PTCs is often similar but not the same as for fuses. Two parameters that fall into this...

 Open the catalog to page 2
POLYFUSE®-3

that the circuit parameters do not exceed these ratings. Determine the following circuit operating parameters: 4. Verify that the ambient operating temperature within close proximity to the device is within its normal operating range. Thermally derate IHOLD and IMAX as necessary. See equation below. • Normal operating current – IHOLD • Maximum circuit voltage – VMAX • Maximum interrupt current – IMAX • Ambient operating temperature 2. Select the suitable form factor. 3. Compare the PTC data sheet ratings on littelfuse.com for VMAX and IMAX to ensure 5. Check that the trip time protects the circuit....

 Open the catalog to page 3
POLYFUSE®-4

Recognized under the Component Program of Underwriters Laboratories to UL Standard 1434 for Thermistors. The devices have also been approved for use in Canada by Underwriters Laboratories. Approvals for fuses include Recognition under the Component Program of Underwriters Laboratories and the CSA Component Acceptance Program. In addition, many fuses are listed in accordance with UL/CSA/ANCE (Mexico) 248-14, Supplemental Fuses. ITU-T Recoomendations CPE (Customer Premises Equipment) The terminology used for PTCs is often similar but not the same as for fuses. Two parameters that fall into this...

 Open the catalog to page 4
POLYFUSE®-5

Recognized under the Component Program of Underwriters Laboratories to UL Standard 1434 for Thermistors. The devices have also been approved for use in Canada by Underwriters Laboratories. Approvals for fuses include Recognition under the Component Program of Underwriters Laboratories and the CSA Component Acceptance Program. In addition, many fuses are listed in accordance with UL/CSA/ANCE (Mexico) 248-14, Supplemental Fuses. ITU-T Recoomendations CPE (Customer Premises Equipment) The terminology used for PTCs is often similar but not the same as for fuses. Two parameters that fall into this...

 Open the catalog to page 5
POLYFUSE®-6

that the circuit parameters do not exceed these ratings. Determine the following circuit operating parameters: 4. Verify that the ambient operating temperature within close proximity to the device is within its normal operating range. Thermally derate IHOLD and IMAX as necessary. See equation below. • Normal operating current – IHOLD • Maximum circuit voltage – VMAX • Maximum interrupt current – IMAX • Ambient operating temperature 2. Select the suitable form factor. 3. Compare the PTC data sheet ratings on littelfuse.com for VMAX and IMAX to ensure 5. Check that the trip time protects the circuit....

 Open the catalog to page 6

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