NTC thermistors for inrush current limiting Leaded and coated disks Series/Type: Date: B57238 March 2006 © EPCOS AG 2006. Reproduction, publication and dissemination of this publication, enclosures hereto and the information contained therein without EPCOS' prior express consent is prohibited. Inrush current limiters B57238 ICLs S238 Applications Switch-mode power supplies Soft-start motors, e.g. in vacuum cleaners Dimensional drawing Features Useable in series connections up to 265 Vrms Coated thermistor disk for line applications Kinked leads of tinned copper wire Wide resistance range UL approval (E69802) Options Resistance tolerance <20% and alternative lead configurations available on request Delivery mode Bulk (standard), cardboard tape, reeled or in Ammo pack Dimensions in mm Approx. weight 3 g General technical data Climatic category Max. power Resistance tolerance Rated temperature B value tolerance Dissipation factor Thermal cooling time constant Heat capacity (IEC 60068-1) (at 25 °C) (in air) (in air) Pmax ∆RR/RR TR ∆B/B δth τc Cth 55/170/21 3.9 ±20 25 ±3 approx. 20 approx. 80 approx. 1600 W % °C % mW/K s mJ/K Electrical specification and ordering codes R25 Imax (0...65 °C) Ω A 2.5 8.4 3 7.4 4.7 6.6 5 6.4 7 6.0 8 5.5 10 5.0 15 4.4 16 4.0 No. of R/T characteristic 1202 1203 1207 1207 1207 1208 1208 1209 1209 B25/100 K 2800 2900 2965 2965 2965 3065 3065 3165 3165 Ctest1) 230 V µF 700 700 700 700 700 700 700 700 700 Ctest1) 110 V µF 2800 2800 2800 2800 2800 2800 2800 2800 2800 Param. for R(I)1) k 0.984 1.04 1.20 1.23 1.34 1.40 1.50 1.67 1.69 Param. for R(I)1) n 1.36 1.36 1.37 1.37 1.38 1.39 1.39 1.40 1.39 Ordering code B57238S0259M000 B57238S0309M000 B57238S0479M000 B57238S0509M000 B57238S0709M000 B57238S0809M000 B57238S0100M000 B57238S0150M000 B57238S0160M000 1) For details on the capacitance Ctest as well as on the parameters k and n refer to "Application Notes", chapters 2.6 and 2.7. Please read Important notes and Cautions and warnings at the end of this document. Page 2 of 6 Inrush current limiters B57238 ICLs R25 Ω 22 25 S238 Imax (0...65 °C) A 4.0 3.4 No. of R/T characteristic 1210 1210 Ctest1) 230 V µF 700 700 B25/100 K 3265 3265 Ctest1) 110 V µF 2800 2800 Param. for R(I)1) k 1.84 1.88 Param. Ordering code for R(I)1) n 1.42 B57238S0220M000 1.40 B57238S0250M000 Reliability data Test Standard Storage in dry heat IEC 60068-2-2 Storage in damp heat, steady state Rapid temperature cycling Endurance Cyclic endurance Transient load Test conditions Storage at upper category temperature T: 170 °C t: 1000 h IEC Temperature of air: 40 °C 60068-2-78 Relative humidity of air: 93% Duration: 21 days IEC Lower test temperature: 55 °C 60068-2-14 Upper test temperature: 170 °C Number of cycles: 10 I = Imax t: 1000 h I = Imax, 1000 cycles On-time = 1 min Cooling time = 6 min Capacitance = Ctest Number of cycles: 1000 ∆R25/R25 (typical) < 10% Remarks < 5% No visible damage < 10% No visible damage < 10% No visible damage No visible damage < 10% < 5% No visible damage No visible damage Cautions and warnings for ICLs The self-heating of a thermistor during operation depends on the load applied and the applicable dissipation factor. When loaded with maximum allowable current/power and the specified dissipation factor is taken as a basis, the NTC thermistor may reach a mean temperature of up to 250 °C. The heat developed during operation will also be dissipated through the lead wires. So the contact areas, too, may become quite hot at maximum load. When mounting NTC thermistors you have to ensure that there is an adequate distance between the thermistor and all parts which are sensitive to heat or combustible. 1) For details on the capacitance Ctest as well as on the parameters k and n refer to "Application Notes", chapters 2.6 and 2.7. Please read Important notes and Cautions and warnings at the end of this document. Page 3 of 6 Inrush current limiters B57238 ICLs S238 Cautions and warnings General See "Important notes" at the end of this document. Storage Store thermistors only in original packaging. Do not open the package before storage. Storage conditions in original packaging: storage temperature 25 °C ... +45 °C, relative humidity ≤75% annual mean, maximum 95%, dew precipitation is inadmissible. Do not store SMDs where they are exposed to heat or direct sunlight. Otherwise, the packing material may be deformed or SMDs may stick together, causing problems during mounting. Avoid contamination of thermistors surface during storage, handling and processing. Avoid storage of thermistor in harmful environments like corrosive gases (SOx, Cl etc). After opening the factory seals, such as polyvinyl-sealed packages, use the SMDs as soon as possible. Solder thermistors after shipment from EPCOS within the time specified: SMDs: 12 months Leaded components: 24 months Handling NTC thermistors must not be dropped. Chip-offs must not be caused during handling of NTCs. Components must not be touched with bare hands. Gloves are recommended. Avoid contamination of thermistor surface during handling. Soldering Use resin-type flux or non-activated flux. Insufficient preheating may cause ceramic cracks. Rapid cooling by dipping in solvent is not recommended. Complete removal of flux is recommended. Mounting When NTC thermistors are encapsulated with sealing material or overmolded with plastic material, the precautions given in chapter “Mounting instructions”, “Sealing, potting and overmolding” must be observed. Electrode must not be scratched before/during/after the mounting process. Contacts and housings used for assembly with thermistor have to be clean before mounting. During operation, the thermistor’s surface temperature can be very high (ICL). Ensure that adjacent components are placed at a sufficient distance from the thermistor to allow for proper cooling ot the thermistors. Ensure that adjacent materials are designed for operation at temperatures comparable to the surface temperature of the thermistor. Be sure that surrounding parts and materials can withstand this temperature. Make sure that thermistors (ICLs) are adequately ventilated to avoid overheating. Avoid contamination of thermistor surface during processing. Please read Important notes and Cautions and warnings at the end of this document. Page 4 of 6 Inrush current limiters B57238 ICLs S238 Operation Use thermistors only within the specified operating temperature range. Use thermistors only within the specified voltage and current ranges (ICLs). Environmental conditions must not harm the thermistors. Use thermistors only in normal atmospheric conditions. Contact of NTC thermistors with any liquids and solvents should be prevented. It must be ensured that no water enters the NTC thermistor (e.g. through plug terminals). For measurement purposes (checking the specified resistance vs. temperature), the component must not be immersed in water but in suitable liquids (e.g. Galden). Avoid dewing and condensation. Be sure to provide an appropriate fail-safe function to prevent secondary product damage caused by malfunction (e.g. use VDR for limitation of overvoltage condition). Please read Important notes and Cautions and warnings at the end of this document. Page 5 of 6 Important notes The following applies to all products named in this publication: 1. Some parts of this publication contain statements about the suitability of our products for certain areas of application. These statements are based on our knowledge of typical requirements that are often placed on our products in the areas of application concerned. We nevertheless expressly point out that such statements cannot be regarded as binding statements about the suitability of our products for a particular customer application. As a rule, EPCOS is either unfamiliar with individual customer applications or less familiar with them than the customers themselves. For these reasons, it is always ultimately incumbent on the customer to check and decide whether an EPCOS product with the properties described in the product specification is suitable for use in a particular customer application. 2. We also point out that in individual cases, a malfunction of passive electronic components or failure before the end of their usual service life cannot be completely ruled out in the current state of the art, even if they are operated as specified. In customer applications requiring a very high level of operational safety and especially in customer applications in which the malfunction or failure of a passive electronic component could endanger human life or health (e.g. in accident prevention or life-saving systems), it must therefore be ensured by means of suitable design of the customer application or other action taken by the customer (e.g. installation of protective circuitry or redundancy) that no injury or damage is sustained by third parties in the event of malfunction or failure of a passive electronic component. 3. The warnings, cautions and product-specific notes must be observed. 4. In order to satisfy certain technical requirements, some of the products described in this publication may contain substances subject to restrictions in certain jurisdictions (e.g. because they are classed as “hazardous”). Useful information on this will be found in our Material Data Sheets on the Internet (www.epcos.com/material). Should you have any more detailed questions, please contact our sales offices. 5. We constantly strive to improve our products. Consequently, the products described in this publication may change from time to time. The same is true of the corresponding product specifications. Please check therefore to what extent product descriptions and specifications contained in this publication are still applicable before or when you place an order. We also reserve the right to discontinue production and delivery of products. Consequently, we cannot guarantee that all products named in this publication will always be available. 6. Unless otherwise agreed in individual contracts, all orders are subject to the current version of the “General Terms of Delivery for Products and Services in the Electrical Industry” published by the German Electrical and Electronics Industry Association (ZVEI). 7. The trade names EPCOS, EPCOS-JONES, Baoke, CeraDiode, CSSP, MLSC, PhaseCap, PhaseMod, SIFI, SIKOREL, SilverCap, SIMID, SIOV, SIP5D, SIP5K, UltraCap, WindCap are trademarks registered or pending in Europe and in other countries. Further information will be found on the Internet at www.epcos.com/trademarks. Page 6 of 6