l l l l l l l l l l l l

Transcription

1 FOODSERVICE HVAC INSTRUMENTATION LIFE SCINECES POWER SUPPLIES

2 Founded in 1958 by Bi Wikinson, Seco Products corporate headquarters is in Reno, Nevada. Our saes force consists of direct and manufacture representatives throughout North America, Canada and Mexico. Every member of our customer support team is dedicated to - providing you with knowedgeabe assistance, timey response to specia requirements, and prompt deivery of your order. Seco has manufacturing faciities in Reno, San Diego, Brazi, China, Japan, Itay, Mexico and United Kingdom. Whie we manufacture our own ine of eectronic contros, we have excusive agreements with seect off-shore manufacturers to suppy us with high quaity eectro-mechanica therma components. Seco handes a marketing and distribution of their products in North America and we aso assist with engineering, quaity assurance, and UL approvas. This aows us to offer a very broad range of products at very competitive prices. A fu range of product ines are offered by Seco incuding therma products, thermistors, contro knobs, eectronic contros and digita pane meters. The therma products ine is comprised of automatic/manua reset bub and capiary thermostats, cod capiary contros, hermeticay seaed thermostats, high temperature thermostats, 1/2 and 3/4 disc thermostats, therma cut-offs, therma protectors and NTC (negative temperature coefficient) thermistors. Contro knobs incude coet, push-on, siders and accessories. Seco s ine of eectronic contros consist of digita temperature and time controers, configurabe controers, digita timer modues and reays. DC and AC votmeters and ammeters, process monitors, setpoint comparators, thermometers, counters, tachometers, are offered in the digita pane meter ine. Seco services both OEM and end-user companies in the foowing industries: HVAC Medica Appiances Eectronics Food Service Process Contros Professiona Audio Teecommunications Industria Instrumentation Seco Strengths JIT program FREE sampes On-time deivery Kanban program One-year warranty Engineering support Vaue Added services Same day shipping from Reno, NV Cost reduction over present source Compete therma component source Specia packaging/abeing/bar coding Prompt, friendy and courteous customer service I S O / A S C e r t i f i e d Q u a i t y S y s t e m SELCO PRODUCTS COMPANY 8780 Technoogy Way Reno, NV (800) (775) FAX (775) E-mai: saes@secoproducts.com w w w. s e c o p r o d u c t s. c o m

3 ELECTRONIC CONTROLS NTC THERMISTORS THERMOSTATS VALUE-ADDED BULB & CAPILLARY THERMOSTATS DIGITAL PANEL METERS COLLET KNOBS & ACCESSORIES PUSH-ON KNOBS & ACCESSORIES SELCO PRODUCTS COMPANY 8780 Technoogy Way Reno, NV (800) (775) FAX (775) E-mai: w w w. s e c o p r o d u c t s. c o m

4 Tabe of Contents Custom NTC Thermistor Probes - CP Series 4-7 Custom NTC Thermistors - CS Series 8-9 Tiny NTC Thermsitor Probes - LS Series 10 Miniature NTC Thermistor Probes - LSMN Mini Series 11 Micro NTC Thermistor Probes - LSMC Micro Series 12 Interchangeabe NTC Thermistors - IN Series Diode Type NTC Thermistors - DT Series 15 Thin Fim NTC Thermistors - TF Series 16 Short Lead NTC Thermistors - HP Series 17 Long Lead NTC Thermistors - HT Series 18 Point Matched NTC Thermistors - PM Series Insuated Lead Thermistors - TS Series 21 Standard SMT NTC Thermistors - SM Series 22 Specia SMT NTC Thermistors - CT Series 23 Packaged NTC Probe Thermistors - TR Series 24 Technica Notes 25 Thermistor Definition Manufacturing Process Resistance - Temperature (R/T) Curves and NTC Therma Time Constant Dissipation Constant Votage/Current Requirements Beta Steinhart-Hart Equation Temperature Rating Stabiity Resistance - Temperature Tabes Appication Notes 28-3

5 Custom NTC Thermistor Probes CP Series Temperature Sensor Appications Househod Appiances Medica Eectronics Industria Eectronics Dryers Infant Incubators Fire Detectors Heaters Bood Anaysis Equipment Soar Coector Toasters Skin Temperature Monitors HVAC Equipment Refrigerators Interna Temperature Sensor Water Purification Coffee Makers Respiration Rate Measurement Pastic Laminating Air Conditioners Eectronic Cinica Thermometer Vending Machines Washing Machines Weding Equipment Weather Monitoring Other Consumer Eectronics Automotive Industria Process Contro Cooing Fan Hybrid Battery Sensor Oceanography Monitoring Battery Pack Water / Oi Tank Sensor Fruit Transportation Process Contro Wireess Card Automatic Cimate Contro Audio Ampifiers Outside Air Temperature Sensor Ceuar Teephones Engine Bock Temperature Sensor Poo and Spa Contro 4

6 Custom NTC Thermistor Probes CP Series FEATURES RoHS Compiant Virtuay unimited options Customer specification or made from stock materias Avaiabe in Interchangeabe or Point Matched toerances CP Series probes are designed to meet your specific appication requirements. Custom probe designs have virtuay unimited options avaiabe. Their vaue-added features significanty reduce your abor costs. Contact our appications engineering personne for assistance in designing a probe from the standard components isted on the foowing pages or from a mutitude of other materias. SPECIFICATIONS Temperature rating/ recommened operating ranges CP Series probes may be intermittenty cyced at temperatures from -50ºC to 150ºC. Optimum stabiity is achieved when they are stored at temperature ess than 50ºC and operated continousy at temperatures ess than 100ºC. Note: CP Series probes using the DT Series gass thermistor may be intermittenty cyced from -50ºC to 250ºC. Optimum stabiity is achieved when they are stored at ess than 50ºC and operated continuousy at temperatures ess than 220ºC. For CP Series probes using interchangeabe thermistor eements, optimum stabiity is achieved when they are operated at temperatures within the specified temperature range. R/T curves Toerances CP Series thermistors probes are avaiabe in a R/T curve materias. Detaied curve materia information on pages ±0.10 C, ±0.20 C, ±0.25 C, ±0.50 C, ±1.00 C, ±1%, ±2%, ±5%, ±10% Note: Seco can provide options such as corrosion resistant housings, high pressure (PSI) housings, custom pastic moded or over-moded thermistor sub assembies, and moisture resistant thermistor probe assembies. Contact Seco appications engineering for information. The foowing are a few exampes of the unimited choices for the combination of wire and probe housings Wire Styes Configuration Gauge Insuation Singe Conductor PVC, XLPE Tefon Zipcord 22- PVC Jacketed PVC, Tefon Twisted PVC, Etched Tefon 5

7 Custom NTC Thermistor Probes CP Series The foowing are a few exampes of the unimited choices for the combination of wire and probe housings Housings Type Materia Threaded NPT fitting round, cose-end tube Brass 316 Stainess Stee Fat cosed-ended PVC, Stainess Stee, Brass, Overmod Rounded, cosed-end cup Derin, Stainess Stee, Brass, Overmod Ring ug termina bot Stee, Copper Ring ug termina bot Stee, Copper Probe 4 Stainess Stee, 316 Stainess Stee, Brass, Auminum, Pastic Threaded NPT pug 4 Stainess Stee, 316 Stainess Stee, Brass, Auminum, Pastic, Overmod Open-end tube 4 Stainess Stee, 316 Stainess Stee, Brass, Auminum, Pastic Expanded Probe 4 Stainess Stee, 316 Stainess Stee, Brass, Auminum, Pastic Tapered-end Probe 4 Stainess Stee, 316 Stainess Stee, Brass, Auminum, Pastic Fange Mount Probe 4 Stainess Stee, 316 Stainess Stee, Brass, Auminum, Pastic 6

8 Custom NTC Thermistor Probes CP Series - Ordering Map ORDERING MAP CP X X X X R/T Curve A = Curve A E = Curve E H = Curve H B = Curve B F = Curve F K = Curve K C = Curve C G = Curve G P = Curve P D = Curve D X = New etter assisgned for specia curve Resistance in Ohms at 25 C 00 = 0 Ohms 001K = 1K Ohms 005K = 5K Ohms 006K = 6K Ohms 010K = 10K Ohms 100K = 100K Ohms 2252 = 2,252 Ohms 1MEG = 1 Miion Ohms X = Specia base resistance vaue IN Type Ony Toerance at 25 C A = ±1.0 C C = ±0.2 C B = ±0.5 C D = ±0.1 C X = new etter assigned on specia PM Type Ony Toerance at 25 C 1 = ±1% 5 = ±5% 2 = ±2% 0 = ±10% 3 = ±3% X = etter or digit assigned for specias IN Type Ony Temperature Ranges 1 = 20 C to 45 C 6 = -40 C to 40 C 2 = -20 C to 50 C 7 = +50 C to 125 C 3 = 0 C to 70 C 8 = 0 C to 50 C 4 = 0 C to 100 C 9 = -20 C to 125 C 5 = +20 C to 90 C X = new digit assigned for specias PM Type Ony Temperature Ranges A = -20 C D = 37 C B = 0 C E = 70 C C = 25 C F = 100 C X = digit to be assigned for specias XXXX = System fie number assigned Note: Other thermistor base resistance vaues, thermistor curves or Beta vaues, or toerances may be avaiabe. Pease contact Seco Products. TO ORDER SPECIFY ALL ITEMS BELOW Lead ength Wire gauge size Soid or stranded wire Probe type description Connectors if required (Moex, Amp or other) Bunt or stripped end and ength of stripped wire Insuation materia (Isomid, Kynar, Nyon, PVC, Tefon, etc.) 7

9 Custom NTC Thermistors CS Series FEATURES RoHS Compiant Customer specified Various materia options Modified stock or new custom design Avaiabe in Interchangeabe or Point Matched toerances CS Series thermistors are designed to meet your specific appication requirements. For turn-key soutions, their vaue-added features can significanty reduce your abor costs. Contact our appications engineering personne for assistance in designing a standard thermistor into a custom thermistor to match your needs. SPECIFICATIONS Temperature rating/ CS Series thermistors may be recommended operating intermittenty cyced at temperatures ranges from -50 C to 150 C. Optimum stabiity is achieved when they are stored at temperatures ess than 50 C and wi operate continuousy in temperatures ess than 100 C. For CS Interchangeabe Series thermistors, optimum stabiity is achieved when they are operated at temperatures within the specified temperature range. R/T curves CS Series thermistors are avaiabe in a R/T curve materias. Detaied curve materia information on pages Toerances ±0.10 C ±0.20 C ±0.25 C ±0.50 C ±1.00 C ±1% ±2% ±3% ±5% ±10% Dissipation constant Therma time constant Maximum power rating Custom options 1m W/ C in sti air 8m W/ C in stirred oi Time constant varies depending on the configuration of each custom thermistor. Typicay 1 second in stirred oi. mw at 25 C to 1mW at 100 C (used in sef-heat appications such as iquid eve contro and air fow sensing). Various ead diameters, insuation materias, ead engths and connectors Note: Severa CS Series Thermistors are avaiabe with UL Component Recognition. Pease contact Seco Products for avaiabiity. 8

10 Custom NTC Thermistors CS Series - Ordering Map ORDERING MAP CS X X X X R/T Curve A = Curve A E = Curve E H = Curve H B = Curve B F = Curve F K = Curve K C = Curve C G = Curve G P = Curve P D = Curve D X = New etter assisgned for specia curve Resistance in Ohms at 25 C 00 = 0 Ohms 001K = 1K Ohms 005K = 5K Ohms 006K = 6K Ohms 010K = 10K Ohms 100K = 100K Ohms 2252 = 2,252 Ohms 1MEG = 1 Miion Ohms X = Specia base resistance vaue IN Type Ony Toerance at 25 C A = ±1.0 C C = ±0.2 C B = ±0.5 C D = ±0.1 C X = new etter Y = ±0.25 C assigned for specias PM Type Ony Toerance at 25 C 1 = 1% 0 = 10% 2 = 2% A = 0.25 C 3 = 3% B = 0.50 C 5 = 5% X = etter or digit to be assigned for specias IN Type Ony Temperature Ranges 1 = +20 C to 45 C 6 = -40 C to 40 C 2 = -20 C to 50 C 7 = +50 C to 125 C 3 = 0 C to 70 C 8 = 0 C to 50 C 4 = 0 C to 100 C 9 = -20 C to 125 C 5 = +20 C to 90 C X = new digit assigned for specias PM Type Ony Temperature Ranges A = -20 C D = 37 C B = 0 C E = 70 C C = 25 C F = 100 C X = digit to be assigned for specias XXXX = System fie number assigned Note: Other thermistor base resistance vaues, thermistor curves or Beta vaues, or toerances may be avaiabe. Pease contact Seco Products. TO ORDER SPECIFY ALL ITEMS BELOW Lead wire ength Wire gauge size Soid or stranded wire Connectors if required (Moex, Amp or other) Bunt or stripped end and ength of stripped wire Insuation materia (Isomid, Kynar, Nyon, PVC, Tefon, etc.) 9

11 Tiny NTC Thermistor Probes LS Series.078 (1.98) diameter LS400 Series Ohms at 25 C A Curve.375 (9.5) Max. AWG 28 Kynar Insuation.078 (1.98) Max. fied PVC cup LS700 Series - A or B Curve.375 (9.5) Max. AWG Kynar Insuation.078 (1.98) Max. fied PVC cup Other vaues and curves avaiabe. Detaied vaues and curve information on pages FEATURES RoHS Compiant Interchangeabe toerance Skin and catheter disposabe sensor designs These thermistors offer a precision method of ife science and patient care temperature sensing. Our disposabe sensors meet the necessity of ow cost without comprising high quaity and precise accuracy. SPECIFICATIONS Temperature rating/ recommended operating ranges R/T curves LS Series thermistors may be intermittenty cyced at temperatures from -50 C to 150 C. Optimum stabiity is achieved when thermistors are operated at temperatures within the specified temperature range. LS Series is manufactured with A or B R/T curve materias. Detaied curve materia information on pages Toerances ±0.10 C ±0.20 C ±0.50 C ±1.00 C Dissipation constant 2.5 mw/ C in sti air 13 mw/ C in stirred oi Therma time constant Typicay 1.25 seconds in stirred oi Custom options Various ead materias, terminations and engths ORDERING MAPS L S A Wire Gauge #28AWG R/T Curve A = A Curve Resistance in 25 C 2252 = 2,252 Ohms 25 C A = ±1.0 C B = ±0.5 C C = ±0.2 C D = ±0.1 C Lead Length Lead Length Exampe 04 = 4.0 Specia Options L S Wire Gauge #AWG R/T Curve A = A Curve B = B Curve Resistance in 25 C 006K = 6,000 Ohms 0K =,000 Ohms 100K = 100,000 Ohms 25 C A = ±1.0 C B = ±0.5 C C = ±0.2 C D = ±0.1 C Lead Length Lead Length Exampe 10 = 10.0 Specia Options Contact Seco Products for your specia requirements. 10

12 Miniature NTC Thermistor Probes LSMN Mini Series and maximum diameter LSMN 400 or 700 Series 400: 2252 Ohms at 25 C A Curve 700: A or B Curves.250 (6.35) Nomina AWG 32 Poy/Nyon.035 (.89) Max. LSMN 400 Series 2252 Ohms at 25 C A Curve fied poyimide tube ( ) Typica FEATURES RoHS Compiant Fast response accuracy to ±0.1 C Interchangeabe or Point Matched toerances.055 (1.4) Max. fied poyimide tube AWG 28 Kynar Insuation Other vaues and curves avaiabe. Detaied vaues and curve information on pages These tiny thermistors can be used in appications that require fast response and sma size. Since they are avaiabe with custom options they can be used in unimited temperature sensing appications in any industry. SPECIFICATIONS Temperature rating/ recommended operating ranges LSMN Series thermistors may be intermittenty cyced at temperatures from -50 C to 150 C. Optimum stabiity is achieved when thermistors are stored at temperatures ess than 100 C. For interchangeabe LSMN Mini Series thermistors optimum stabiity is achieved when they are operated at temperatures within the specified temperature range. Note: Probe housing engths avaiabe from.125 to.375 ( ) R/T curves LSMN Mini Series is manufactured with A or B R/T curve materias. Detaied curve materia information on pages Toerances ±0.10 C, ±0.20 C, ±0.25 C, ±0.50 C, ±1.00 C, ±1%, ±2%, ±3%, ±5%, ±10% Dissipation constant 1.5 mw/ C in sti air 10 mw/ C in stirred oi Therma time constant Typicay 0.4 seconds in stirred oi Custom options Various ead materias and engths L S M N A ORDERING MAPS R/T Curve A = A Curve Resistance in 25 C 2252 = 2,252 Ohms 25 C A = ±1.0 C 1 = ±1% B = ±0.5 C 2 = ±2% C = ±0.2 C 3 = ±3% D = ±0.1 C 4 = ±4% X = SPECIAL 5 = ±5% Wire Gauge and Probe Diameter 2 = #28AWG, Probe Diameter 3 = #32AWG, Probe Diameter Lead Length or Specia Options L S M N R/T Curve A = A Curve B = B Curve Resistance in 25 C 006K = 6,000 Ohms 010K = 10,000 Ohms 0K =,000 Ohms 25 C A = ±1.0 C 1 = ±1% B = ±0.5 C 2 = ±2% C = ±0.2 C 3 = ±3% D = ±0.1 C 4 = ±4% X = SPECIAL 5 = ±5% Wire Gauge and Probe Maximum Diameter 2 = #28AWG, Probe Diameter 3 = #32AWG, Probe Diameter Lead Length or Specia Options Contact Seco Products for your specia requirements. 11

13 Micro NTC Thermistor Probes LSMC Micro Series and max. dia. capabiity to dia. LSMC 700 Series 10K Ohms, K Ohms, or 100K Ohms at 25 C A Curve.156 (3.96) Nomina AWG 38 Heavy Isomid insuation.0185 (.469) Max. fied poyimide tube LSMC 400 Series 2252 Ohms at 25 C A Curve. (7.62) Nomina AWG 38 Heavy Isomid insuation.0190 (.48) Max. fied poyimide tube Other vaues and curves avaiabe. Detaied vaues and curve information on pages FEATURES RoHS Compiant Fast response accuracy to ±0.1 C Interchangeabe or Point Matched toerances These tiny thermistors can be used in many Life Science appications. They are sma enough to fit into a hypodermic neede. Since they are avaiabe in many custom options they can be used for fast response temperature sensing appications in any industry. SPECIFICATIONS Temperature rating/ recommended operating ranges LSMC Series thermistors may be intermittenty cyced at temperatures from -50 C to 150 C. Optimum stabiity is achieved when thermistors are stored at temperatures ess than 50 C. and operated continuousy in temperatures ess than 100 C. For interchangeabe LSMC Series thermistors optimum stabiity is achieved when they are operated at temperatures within the specified temperature range. R/T curve Toerances Dissipation constant Therma time constant Lead materias LSMC Series is manufactured with A R/T curve materia. Detaied curve materia information on pages ±0.10 C, ±0.20 C, ±0.25 C, ±0.50 C ±1.00 C, ±1%, ±2%, ±5%, ±10% 0.3 mw/ C in sti air 2.5 mw/ C in stirred oi Typicay 0.4 seconds in stirred oi AWG 38 nicke aoy or copper conductors with heavy isomid insuation, parae bonded configuration. L S M C A ORDERING MAP R/T Curve A = A Curve Resistance in 25 C 2252 = 2,252 Ohms 25 C A = ±1.0 C 1 = ±1% B = ±0.5 C 2 = ±2% C = ±0.2 C 3 = ±5% D = ±0.1 C 4 = ±10% X = SPECIAL Lead Length or Specia Options L S M C A R/T Curve A = A Curve Resistance in 25 C 010K = 10,000 Ohms 0K =,000 Ohms 100K = 100,000 Ohms 25 C A = ±1.0 C 1 = ±1% B = ±0.5 C 2 = ±2% C = ±0.2 C 3 = ±5% D = ±0.1 C 4 = ±10% X = SPECIAL Lead Length or Specia Options Contact Seco Products for your specia requirements. 12

14 Interchangeabe NTC Thermistors IN Series FEATURES RoHS Compiant Sma size with ease of handing High accuracy toerance to ±0.10 C Operating ranges from -50 C to 150 C Proprietary processes produce top of the ine quaity and stabiity SPECIFICATIONS Interchangeabe refers to how accuratey thermistors foow the R/T curve over a range of temperatures. This aows every thermistor of the same series specifications to be exchangeabe. Temperature rating/ recommended operating ranges Temperature ranges -20 C to 50 C 0 C to 50 C 20 C to 45 C 0 C to 70 C 0 C to 100 C Toerances ±0.10 C ±0.20 C ±0.50 C ±1.00 C IN Series thermistors may be intermittenty cyced at temperatures from -50 C to 150 C. Optimum stabiity is achieved when they are operated at temperatures within the specified temperature range. R/T curves IN Series thermistors are avaiabe in a R/T curve materias. Detaied curve materia information on pages Dissipation constant 2m W/ C in sti air 13m W/ C in stirred oi Therma time constant Typicay 0.75 seconds in stirred oi Maximum power rating mw at 25 C to 1mW at 100 C 13

15 Interchangeabe NTC Thermistors IN Series - Order Map ORDERING MAP IN- - - XX R/T Curve A = Curve A E = Curve E H = Curve H B = Curve B F = Curve F K = Curve K C = Curve C G = Curve G P = Curve P D = Curve D X = New etter assisgned for specia curve Resistance in Ohms at 25 C 001K = 1K Ohms 003K = 3K Ohms 006K = 6K Ohms 010K = 10K Ohms 020K = 20K Ohms 0K = K Ohms 100K = 100K Ohms 2252 = 2,252 Ohms X = specia base resistance vaue Toerance at 25 C A = ±1.0 C B = ±0.5 C C = ±0.2 C D = ±0.1 C X = new etter Y = ±0.25 C assigned for specias Temperature Ranges 1 = +20 C to 45 C 6 = -40 C to 40 C 2 = -20 C to 50 C 7 = +50 C to 125 C 3 = 0 C to 70 C 8 = 0 C to 50 C 4 = 0 C to 100 C 9 = -20 C to = +20 C to 90 C X = new digit assigned for specias 2 Leads 3 Leads Code AWG Lead O.D. Lead Type Chip Coating Code AWG Lead O.D. Lead Type Chip Coating Tinned Aoy Nicke Tinned Aoy 180 Nicke Tinned Aoy 180 Tinned Aoy 180 Nicke Uncoated * * 6K to K ony Nicke Tinned Aoy 180 Tefon Ag/Cu Twisted Kynar For optiona engths other than 2 or 3 substitute XX with engths in inches Exampe: 04 = 4.0 Note: Other thermistor base resistance vaues, thermistor curves or Beta vaues, or toerances may be avaiabe. Pease contact Seco Products. Custom designs are avaiabe, pease fax or e-mai us your requirements 14

16 Diode Type NTC Thermistors DT Series FEATURES RoHS Compiant Gass seaed body for high reiabiity High stabiity and ow cost Exceent therma cyce endurance Leads may be precut and custom formed to your specification The DT thermistor is a therma sensor in a DO35 package. The highy reiabe thermistor is offered in a wide temperature range of -50 C to 250 C. It can be used in a variety of appications incuding high temperature appications. SPECIFICATIONS Temperature range -50 C to 250 C R25 Rated Zero-power Resistance vaue at 25 C 10,000 Ohms 15,000 Ohms,000 Ohms 47,000 Ohms 50,000 Ohms 100,000 Ohms 200,000 Ohms 500,000 Ohms Toerances ±1%, ±3%, ±5% B vaue A Curve = 3977K C Curve = 3695K D Curve = 4262K F Curve = 3435K Determined by rated zero-power resistance at 25 C and 85 C Dissipation constant Minimum 2.4 mw/ C Therma time constant Typicay 3.0 seconds in sti air Typicay 1.0 seconds in oi bath Maximum power rating 250 mw at 25 C ORDERING MAP DT - - R/T CURVE A = Curve A C = Curve C D = Curve D F = Curve F X = New etter assigned for specia curve Resistance in 25 C 010K = 10K Ohms 015K = 15K Ohms 0K = K Ohms 047K = 47K Ohms 050K = 50K Ohms 100K = 100K Ohms 200K = 200K Ohms 500K = 500K Ohms X = Specia base resistance vaue Toerances 1 = ±1% 3 = ±3% 5 = ±5% Optiona Specia Specification Note: Some products within the DT Series are avaiabe with UL component recognition. Pease contact Seco Products or visit our website for avaiabiity. Note: Other thermistor base resistance vaues, thermistor curves or Beta vaues, or toerances may be avaiabe. Pease contact Seco Products. 15

17 Thin Fim NTC Thermistors TF Series FEATURES RoHS Compiant Rapid response time Suitabe for narrow space Note: L:.59 (15mm).98 (25mm) 1.97 (50mm) 2.95 (75mm) The TF thermistor features utra thinness of 500 :m and superior eectrica insuation. It may safey be used in surroundings that incudes contacts with eectrodes. SPECIFICATIONS Temperature range -50 C to 90 C R25: Rated Zero-power 10,000 Ohms Toerances ±1% ±3% ±5% B vaue 3977K, 3435K Determined by rated zero-power resistance at 25 C and 85 C R/T curves A Curve F Curve Dissipation constant 0.7 mw/ C in sti air Therma time constant Typicay 2.0 seconds in air Typicay 0.8 seconds in stirred oi bath Maximum power rating 3.5 mw at 25 C RoHS Compiant ORDERING MAP T F K - - R/T Curve A = A Curve F = Curve F X = New etter assigned for specia curve Resistance in Ohms at 25 C 010K = 10K Ohms X = Specia base resistance vaue Toerances 1 = ±1% 3 = ±3% 5 = ±5% Overa Length 1 =.59 (15mm) 2 =.98 (25mm) 3 = 1.97 (50mm) 4 = 2.95 (75mm) Optiona Specia Specification Note: Pease contact Seco Products regarding TF Series product with UL Component Recognition. Note: Other thermistor base resistance vaues, thermistor curves or Beta vaues, or toerances may be avaiabe. Pease contact Seco Products. 16

18 Short Lead NTC Thermistors HP Series.14 (3.5) Max (3.0) Max. FEATURES RoHS Compiant High stabiity and ow cost Exceent therma cyce endurance Tiebar cut aows consistent, accurate pacement 0.67 ±.06 (17±1.5) 0.34 ±1 (8.5±1).16 (4.0) Max..03 (0.7) Tiebar cut.02 ( 0.5) Tin-Pated Copper Bue coor resin.02 ( 0.5) Tin-Pated Copper Leads The HP thermistor is a high-performance therma sensing device. 0.10± 0.25 (2.54± 0.25) SPECIFICATIONS Temperature range -50 C to 110 C R25: Rated Zero-power resistance vaue at 25 C 1,000 Ohms 2,000 Ohms 5,000 Ohms 10,000 Ohms 20,000 Ohms 47,000 Ohms 100,000 Ohms Toerances ±1%, ±3%, ±5% B vaue 3435K K Determined by rated zero-power resistance at 25 C and 85 C R/T curves HP Series thermistors are avaiabe in a R/T curve materias. Detaied curve materia information on pages Dissipation constant 2 mw/ C Therma time constant Typicay 3.0 seconds in air Typicay 1.0 seconds in oi bath Maximum power rating mw at 25 C H P ORDERING MAP R/T Curve A = Curve A F = Curve F B = Curve B G = Curve G C = Curve C H = Curve H D = Curve D K = Curve K E = Curve E P = Curve P X = New etter assigned for specia curve Resistance in Ohms at 25 C 001K = 1K Ohms 002K = 2K Ohms 005K = 5K Ohms 010K = 10K Ohms 020K = 20K Ohms 047K = 47K Ohms 100K = 100K Ohms X = Specia base resistance vaue Toerances 1 = ±1% 3 = ±3% 5 = ±5% Optiona Specia Specification Note: Other thermistor base resistance vaues, thermistor curves or Beta vaues, or toerances may be avaiabe. Pease contact Seco Products. 17

19 Long Lead NTC Thermistors HT Series.157 (4.0) Max..138 (3.5) Max. FEATURES RoHS Compiant High stabiity and ow cost Exceent therma cyce endurance 1.18 ±.059 (±1.5).157 (4.0) Max..019 ( 5) Tin-Pated Copper Leads 0.1 (2.54) Back coor resin.019 ( 5) Tin-Pated Coppper Leads The HT thermistor is a high-performance therma sensing device. SPECIFICATIONS Temperature range -50 C to 110 C R25: Rated zero-power resistance vaue at 25 C 1,000 Ohms 2,000 Ohms 5,000 Ohms 10,000 Ohms 20,000 Ohms 47,000 Ohms 100,000 Ohms Toerances ±1%, ±3%, ±5% B vaue 3435K K Determined by rated zero-power resistance at 25 C and 85 C R/T curves HT Series thermistors are avaiabe in most of the R/T curve materias. Detaied curve materia information on pages Dissipation constant 2 mw/ C Therma time constant Typicay 3.0 seconds in air Typicay 0.9 seconds in oi bath Maximum power rating mw at 25 C ORDERING MAP H T R/T Curve A = Curve A D = Curve D G = Curve G B = Curve B E = Curve E K = Curve K C = Curve C F = Curve F P = Curve P X = New etter assigned for specia curve Resistance in Ohms at 25 C 001K = 1K Ohms 002K = 2K Ohms 005K = 5K Ohms 010K = 10K Ohms 020K = 20K Ohms 047K = 47K Ohms 100K = 100K Ohms X = Specia base resistance vaue Toerances 1 = ±1% 3 = ±3% 5 = ±5% Optiona Specia Specification Note: Other thermistor base resistance vaues, thermistor curves or Beta vaues, or toerances may be avaiabe. Pease contact Seco Products. 18

20 Point Matched NTC Thermistors PM Series FEATURES RoHS Compiant Percentage (%) or degree C toerance Reduced cost for high voume appications Toerance resistance matched to specific temperature PM Series thermistors are precision tested at a chosen toerance to a specific temperature. This cost effective thermistor provides an advantage to industries with high voume appications, such as in HVAC, automotive, and industria markets. SPECIFICATIONS Temperature rating/ recommended operating ranges R/T curves Temperature ranges PM Series thermistors may be intermittenty cyced at temperatures from -50 C to 150 C. Optimum stabiity is achieved when they are stored at temperatures ess than 50 C and operated continuousy in temperatures ess than 100 C. PM Series thermistors are avaiabe in a R/T curve materias. Detaied curve materia information on pages C 0 C 25 C 37 C 70 C 100 C Toerances Dissipation constant Therma time constant Maximum power rating ±0.25 C ±1.0 C ±1% ±2% ±3% ±5% 2m W/ C in sti air 13m W/ C in stirred oi Typicay 0.75 seconds in stirred oi mw at 25 C to 1mW at 100 C (used in sef-heat appications such as iquid eve contro and air fow sensing). 19

21 Point Matched NTC Thermistors PM Series - Order Map ORDERING MAP PM XX R/T Curve A = Curve A E = Curve E H = Curve H B = Curve B F = Curve F K = Curve K C = Curve C G = Curve G P = Curve P D = Curve D X = New etter assisgned for specia curve Resistance in Ohms at 25 C 001K = 1K Ohms 005K = 5K Ohms 006K = 6K Ohms 010K = 10K Ohms 100K = 100K Ohms 2252 = 2,252 Ohms 1MEG = 1 Miion Ohms X = Specia base resistance vaue Toerance at 25 C 1 = ±1% 0 = ±10% 2 = ±2% A = ±0.25 C 3 = ±3% B = ±0.50 C 5 = ±5% X = etter or digit to be assigned for specias Temperature Ranges A = -20 C D = 37 C B = 0 C E = 70 C C = 25 C F = 100 C x = digit to be assigned for specias 2 Leads 3 Leads Code AWG Lead O.D. Lead Type Chip Coating Code AWG Lead O.D. Lead Type Chip Coating Tinned Aoy Nicke Tinned Aoy 180 Nicke Tinned Aoy 180 Tinned Aoy Tinned Aoy Nicke * * 6K to K ony Nicke Tinned Aoy 180 Tefon Ag/Cu Twisted Kynar For optiona engths other than 2 or 3 substitute XX with engths in inches Exampe: 04 = 4.0 Note: Other thermistor base resistance vaues, thermistor curves or Beta vaues, or toerances may be avaiabe. Pease contact Seco Products. 20

22 Insuated Lead Thermistors TS Series.063 (1.6) Max. Poyurethane Insuation.118 ±.039 (3.0 ± 1.0) 3.42 ±.118 (87.0 ± 3.0) Coating (Back) Copper Aoy Insuated wire - 32AWG.157 (4.0) Max. FEATURES Fast response RoHS Compiant Poyurethane insuated eads Exceent therma cyce endurance The TS thermistor is smaer than the HP and IN thermistors. It s rapid response time and high reiabiity make it suitabe for use in medica equipment and thermometers. SPECIFICATIONS Temperature range -50 C to 110 C R25: Rated Zero-power resistance vaue at 25 C 1,000 Ohms Resistance 2,000 Ohms 2,252 Ohms 4,000 Ohms 5,000 Ohms 10,000 Ohms 20,000 Ohms,000 Ohms 50,000 Ohms 100,000 Ohms 232,000 Ohms Toerances ±1%, ±3%, ±5% B vaue 3435K K Determined by rated zero-power resistance at 25 C and 85 C R/T curves TS Series thermistors are avaiabe in most of the R/T curve materias. Detaied curve materia information on pages Dissipation constant 0.7 mw/ C Therma time constant Typicay 1.0 seconds in air Typicay 0.8 seconds in oi bath Maximum power rating 3.5 mw at 25 C ORDERING MAP T S - - R/T Curve A = Curve A B = Curve B C = Curve C D = Curve D F = Curve F K = Curve K I = Curve I X = New etter assigned for specia curve Resistance in Ohms at 25 C 001K = 1K Ohms 002K = 2K Ohms 2252 = 2252 Ohms 004K = 4K Ohms 005K = 5K Ohms 010K = 10K Ohms 020K = 20K Ohms 0K = K Ohms 050K = 50K Ohms 100K = 100K Ohms 232K = 232K Ohms X = Specia base resistance vaue Curve Avaiabiity A, I A, I A A A, F, K A, B, C, F, K A A, B A A, B, D D Resistance Toerance 1 = ±1% 3 = ±3% 5 = ±5% Optiona Specia Specification Note: Other thermistor base resistance vaues, thermistor curves or Beta vaues, or toerances may be avaiabe. Pease contact Seco Products. 21

23 Standard SMT NTC Thermistors SM Series FEATURES RoHS Compiant Surface mount capabiity Utra sma size and ow capacitance Uniformy sized for pick pace assemby This highy reiabe SM thermistor is characterized by a fast response time due to the surface mounting on a PCB. Our manufacturing techniques produce the highest quaity surface mount thermistors avaiabe in today s market. Type Dim. L (±0.2).126 ().0787 (2.0).063 (1.6).039 (1.0) W (±0.2).063 (1.6).0492 (1.25).0315 (0.8).0197 (0.5) L (2.0).0551 (1.4).0472 (1.0).0276 (0.7) A (±0.2) (0.2).0118 (0.2).0079 (0.2) H (±0.2).0433 (1.1).0118 (0.3).0118 (0.3).0236 (0.5) SPECIFICATIONS Temperature range -40 C to 125 C R25: Rated Zero-power 10,000 Ohms resistance vaue at 25 C Note: Other base resistance and R-T curves avaiabe upon request. Pease contact Seco Products. Toerances ±1% ±3% ±5% B25/85 vaue 10,000 Ohms - F Curve (3435K) Dissipation constant 3.5 mw/ C in sti air Therma time constant Typicay 5-8 seconds in sti air Maximum power rating mw at 25 C Ree quantity K ree K ree K ree K ree ORDERING MAP SM - - F K - Size Type Curve/Resistance in 25 C F010K = Curve F 10K Ohms 25 C 1 = ±1% 3 = ±3% 5 = ±5% Packaging T = Tape Ree B = Buk Note: Other thermistor base resistance vaues, thermistor curves or Beta vaues, or toerances may be avaiabe. Pease contact Seco Products. 22

24 Specia SMT NTC Thermistors CT Series FEATURES RoHS Compiant Surface mount capabiity Utra sma size and ow capacitance Uniformy sized for pick pace assemby The CT thermistor, a highy reiabe thermistor, is characterized by a fast response and standard chip package sizes. Type Dim. L (±0.2).126 ().0787 (2.0).063 (1.6) W (±0.2).063 (1.6) (1.25).0315 (0.8) L1 A R.0787 (2.0).0551 (1.4) (1.2).0236 (0.6).0118 (0.3).0079 (0.2).0146 (0.37).0079 (0.20).0067 (0.17) H (±0.2).0433 (1.1).0433 (1.1).0315 (0.8) T (±0.05).0197 (0.5).0197 (0.5).0118 (0.3) SPECIFICATIONS Temperature range -40 C to 125 C R25: Rated Zero-power 10,000 Ohms Resistance vaue at 25 C Toerances ±5% B25/85 vaue 10,000 Ohms - F Curve (3435K) Dissipation constant Therma time constant 0.9 mw/ C in sti air Typicay 3-8 seconds in sti air Maximum power rating 4-6 mw at 25 C Ree quantity K ree K ree K ree ORDERING MAP CT - - F K - Size Type Curve/Resistance in 25 C F010K = Curve F 10K Ohms 25 C 5 = ±5% Packaging T = Tape Ree B = Buk Note: Other thermistor base resistance vaues, thermistor curves or Beta vaues, or toerances may be avaiabe. Pease contact Seco Products. 23

25 Packaged NTC Probe Thermistors TR Series FEATURES RoHS Compiant High utiity products Compact stainess stee case Appropriate to use in harsh environmenta conditions The TR thermistors are used widey in househod appiances, such as washing machines, dishwashers, tumbe-dryers, and water boiers. SPECIFICATIONS Temperature range -40 C to 125 C R25: Rated Zero-power 10,000 Ohms Resistance vaue at 25 C 11,982 Ohms 48,150 Ohms 100,000 Ohms Toerances ±1% ±3% ±5% B25/85 vaue 10,000 ohms K 48,150 ohms K 100,000 ohms K B25/100 vaue 11,982 ohms K Dissipation constant 215 mw/ C in sti water Therma time constant Typicay 18 seconds in water Maximum power rating 250~500 mw at 25 C ORDERING MAP T R Transducer Type Thermistor Resistance in 25 C 010K = 10,000 Ohms 011K = 11,982 Ohms 048K = 48,150 Ohms 100K = 100,000 Ohms Beta Vaue 3435 = 10,000 Ohms (25 C/85 C) 3977 = 48,150 Ohms (25 C/85 C) 4150 = 100,000 Ohms (25 C/85 C) 3760 = 11,982 Ohms (25 C/100 C) Resistance Toerance 1 = ±1% 3 = ±3% 5 = ±5% 24

26 Technica Notes Negative Temperature Coefficient (NTC) Thermistors Thermistor Definition The word thermistor is derived from its description therma sensitive resistor Thermistors are passive semiconductors, which produce resistance vaues dependent on temperature. A Negative Temperature Coefficient (NTC) thermistor decreases in resistance as its body temperature increases. In fact, NTC thermistors exhibit two characteristics, which make them extremey usefu in a variety of appications. Their change in resistance is predictabe and it is reativey arge per degree change in temperature. Manufacturing Process This is a two-step process of chip manufacturing and thermistor assemby. Manufactured chips are processed by meta oxide powders into ceramic sheets. These sheets are metaized with siver to aow for eectrica contact. After metaization, the ceramic sheets are diced into chips. Each chip is tested to meet our superior quaity standards. After a chip has been manufactured and tested, eads are attached. The chip is trimmed to meet the specified toerance, and then a protective coating is added. Further customizing of the assemby can be done by adding housings, cabes, and connectors. Thermistor quaity is assured with in-process inspection and Statistica Process Contro (SPC). This process takes pace at each manufacturing and assemby step. A finished products are 100% tested both eectricay and mechanicay to guarantee a specifications are met. Resistance-Temperature (R/T) Curves and Negative Temperature Coefficient Nine different materias are made, each with its own unique and predictabe resistance-temperature characteristics. These characteristics are caed curves. Thermistors are most often specified by their curve and by their resistance vaue at 25 C. The NTC (Negative Temperature Coefficient) is the negative percent resistance change per degree C. Our thermistors have NTC vaues at 25 C ranging from -3.7%/ C to -6.4%/ C. Resistance vaues at 25 C range from 0 ohms to 1 meg ohms. The tabes on pages detai this information. Therma Time Constant Time constant, expressed in seconds, is the time required for a thermistor to indicate 6% of a newy impressed temperature. The time constant of a thermistor is directy affected by the mass of the thermistor and therma couping to the environment. An epoxy or phenoic coated thermistor with a O.D., wi typicay have a time constant of 0.75 seconds in stirred oi and 10 seconds in sti air. Dissipation Constant Dissipation constant is the power required to raise the temperature of a thermistor 1 C above the surrounding environment. Power is expressed in watts. The dissipation constant of a thermistor with a O.D., coated with epoxy or phenoic, is typicay 13 mw/ C in stirred oi and 2 mw/ C in sti air. Votage/Current Requirements Very ow current is required for a thermistor being used in temperature measurement, contro or compensation appications. Current eves shoud typicay be ess than 100mA for a thermistor to dissipate zero power. As previousy discussed, power dissipation for a thermistor in sti air is approximatey 2mW/ C. Therefore, in order to keep the therma error (sef-heat) beow 0.1 C, the power dissipation must be ess than 0.2 mw. Sef-heating is desirabe in appications such as air fow measurement and iquid eve contro. Standard epoxy or phenoic coated thermistors with a O.D., have a maximum power rating of miiwatts at 25 C to 1 miiwatt at 100 C. Beta The Beta vaue describes the steepness of R/T curve. The arger vaue Beta equas a steeper R/T curve. The Beta vaue of a thermistor is one way to characterize its resistance temperature reationship. Beta is dependent on two reference temperatures. Seco Products uses 25 C and 85 C as its standard. Beta is cacuated as foows: $ T2/T1 = Ln(RT2/RT1)/(1T2-1T/1) Temperature is in degrees Kevin; RT1 is the resistance at temperature T1; RT2 is the resistance at temperature T2. Steinhart-Hart Equation The Steinhart-Hart Equation is an empiricay deveoped poynomia which best represents the resistance-temperature reationships of NTC thermistors. The Steinhart-Hart Equation is more accurate than previous methods. Specificay, it is more accurate over wider temperature ranges. To sove temperature when resistance is known, the form of the equation is: 1/T=a+b(Ln(R))+c(Ln(R)) 3 To sove for resistance when temperature is known, the form of the equation is: R=e(exp)[-a/2+(a 2 /4+a 3 /27) -2 ) -3 +(-a/2-(a 2 /4+a 3 /27) 2 ) 3 ] where apha = (a-1/t)/c and $ = b/c For both forms of the equation T is temperature expressed in degrees Kevin; a, b, and c can be soved simutaneousy using the foowing: 1/T1=a+b(LnR1)+c(LnR1) 3 1/T2=a+b(LnR2)+c(LnR2) 3 1/T3=a+b(LnR3)+c(LnR3) 3 The data cacuated by these equations wi be accurate to better than ±0.01 C when -40 C is ess than or equa to 150 C and T1-T2 is ess than or equa to 50 C and T2-T3 is ess than or equa to 50 C and T1, T2, and T3 are eveny spaced. Maximum Temperature Rating/Recommended Operating Ranges Our thermistors may be intermittenty cyced at temperatures from -50 C to 150 C. Stabiity is achieved when the thermistors are stored at temperatures ess than 50 C and operated continuousy at temperatures ess than 100 C. The DT Series thermistor has a temperature range from -50 C to +250 C. For interchangeabe thermistors, optimum stabiity is achieved when the thermistors are operated at temperatures within the specified temperature range. Stabiity Years of experience in thermistor manufacturing, couped with stringent process contros, ensures that highy stabe thermistors are produced. In fact, our thermistors typicay exhibit ess than 0.02 C thermometric drift per year when stored or operated at temperatures ess than 50 C. The stabiity of a thermistor is greaty dependent on environmenta conditions such as humidity, excessive temperatures and therma shock. These effects shoud be minimized to guarantee stabiity. 25

27 Resistance - Temperature Tabe Ratio is the resistance at temperature divided by the resistance at 25 C. To find the actua resistance vaue at the temperatures isted in the charts, mutipy the R25 vaue by the number isted in the Ratio coumn next to the corresponding temperature. As an exampe, a Curve A thermistor with a temperature toerance of ±1 C over the temperature range 0 to 70 C woud have the foowing resistance toerance: 0 C = ±5.1%; 25 C = ±4.4%; 70 C = ±3.4% NTC (Negative Temperature Coefficient) is the negative percent resistance change per degree C. To determine the resistance toerance of a precision thermistor at any temperature point mutipy the temperature toerance times the NTC. Curve A Curve B Curve C Curve D Curve E $ at 25 C/85 C 3977K 3942K 3695K 4262K 4434K $ at 0 C/50 C 3892K 3813K 3575K 4141K 4276K Typica R25 = 1K to 100K Typica R25 = 10K to 100K Typica R25 = 5K to 20K Typica R25 = 25K to 100K Typica R25 = 1K to 200K Temperature C RT/R25 RATIO RT/R25 RATIO RT/R25 RATIO RT/R25 RATIO RT/R25 RATIO RATIO NTC RATIO NTC RATIO NTC RATIO NTC RATIO NTC

28 Resistance - Temperature Tabe Curve F Curve G Curve H Curve I Curve K Curve P $ at 25 C/85 C 3435K 4390K 4847K 3535K 3485K 4144K $ at 0 C/50 C 3320K 4269K 4669K 3419K 3405K 3988K Typica R25 = 10K Typica R25 = 10K Typica R25 = 1MEG Typica R25 = 2K to 20K Typica R25 = 200 to 2K Typica R25 = 100K Temperature C RT/R25 RATIO RT/R25 RATIO RT/R25 RATIO RT/R25 RATIO RT/R25 RATIO RT/R25 RATIO RATIO NTC RATIO NTC RATIO NTC RATIO NTC RATIO NTC RATIO NTC

29 Appication Notes NTC Thermistor Appications Introduction Our NTC chip thermistors are exceent soutions in appications requiring temperature measurement and compensation from -50 to 150 C. Figure 1: Wheatstone Bridge - Votage Mode T1 = 10K ohm A Curve R1 = 4980 ohm R2 = 4980 ohm R3 = 10K ohm RTDs, thermocoupes and siicon semiconductors cannot compete with the thermistor s sensitive response to temperature. This sensitivity is crucia for accurate temperature measurement. Unike RTDs and thermocoupes, thermistors are virtuay unaffected by ead resistance. This makes NTC thermistors the sensor of choice for remote sensing appications. With their exceent ong term stabiity characteristics, design engineers utiize thermistors in critica appications for the medica, miitary, aerospace, industria and scientific industries. Systems utiizing thermistors are ess expensive to produce than other soutions because fewer associated components are required for a high performance system. Chip thermistors can be ordered with tight toerances to ±0.1 C, eiminating the costy caibration process required by temperature sensors such as siicon semiconductors, RTDs, thermocoupes and gass beaded and disk thermistors with oose toerances. Figure 2: Wheatstone Bridge - Votage Mode NTC thermistors provide the design engineer with desirabe sensor performance advantages in a variety of appications. The foowing notes provide a few exampes of how to utiize the NTC thermistor. Zero Power Sensing - Dissipation Constant When utiizing a thermistor for temperature measurement, contro, and compensation appications, it is very important not to sef-heat the thermistor. Power, in the form of heat, is produced when current is passed through the thermistor. Since a thermistor s resistance changes when temperature changes, this sef generated heat wi change the resistance of the thermistor, producing an erroneous reading. The power dissipation constant is the amount of power required to raise a thermistor s body temperature 1 C. A standard chip thermistor has a power dissipation constant of approximatey 2mW/ C in sti air. In order to keep the sef-heat error beow 0.1 C power dissipation must be beow 0.2mW. Very ow current eves are required to obtain such a ower power dissipation factor. This mode of operation is caed zero power sensing. Figure 3: Wheatstone Bridge - Votage Mode T1 = K ohm B Curve T2 = 6K ohm A Curve R1 = 5420 ohm R2 = 3970 ohm R3 = 3970 ohm R4 = ohm Thermistor Linearization - Votage Mode Wheatstone Bridge - Votage Mode To produce a votage output that varies ineary with temperature, utiize the NTC thermistor as the active eg in a Wheatstone Bridge. As temperature increases, the votage output increases. The circuit in Figure 1 produces an output votage that is inear with ±0.06 C from 25 C to 45 C. This circuit is designed to produce 1V at 25 C and 200mW at 45 C; this is achieved by the seection of R2 and R3. The vaue of R1 is seected to best provide inearization of the 10K ohm thermistor over the 25 C to 45 C temperature range. Figure 2 iustrates the output votage of the Wheatstone Bridge as a function of temperature. The circuit in Figure 3 provides improved output accuracy over a wide temperature range by substituting a 6K/K ohm thermistor network in pace of the singe thermistor in the Wheatstone Bridge. This circuit is designed to provide 0V at 0 C and 537mV at 100 C. The maximum inear deviation of this circuit is ±0.234 C from 0 C to 100 C. 28

30 Appication Notes Thermistor Linearization Operationa Ampifier - Resistance Mode A inear votage output that varies with temperature can aso be produced by utiizing an operationa ampifier and a inearized thermistor network as iustrated in Figure 4. The votage output decreases ineary as temperature increases. This circuit may be caibrated by adjusting R3 for an output votage of 200mW at 25 C and 0V at 45 C. Figure 4: Linearization - Resistance Mode T1 = 10K ohm A Curve R1 = 4980 ohm R2 = 5K ohm R3 = 10K ohm potentiometer Temperature Measurement and Contro Digita Thermometer The most common appication for the NTC thermistor is temperature measurement. Accurate temperature measurement can easiy be accompished by interfacing a Wheatstone Bridge, 6K/K ohm thermistor network and a digita votmeter integrated circuit as iustrated in Figure 5. The IC consist of an anaog to digita converter with buit-in 3-1/2 digit LCD driver providing resoution of 0.1 C. Using the 6K/K ohm thermistor network makes it possibe to achieve an overa system accuracy of ±0.4 C from 0 C to 100 C. This digita thermometer can easiy be interfaced with additiona circuitry to provide a temperature contro circuit with a digita dispay. Figure 5: Digita Thermometer R7 = 1.50K ohm R8 = 100K ohm R9 = 470K ohm R10 = 15K ohm C1 = 100 pf C2 = 0.22 C4 = 0.1 Micro Controer System The advent of ow cost micro controers used with precision interchangeabe NTC thermistors, provides the design engineer with unimited design possibiities for temperature measurement and contro systems. These systems are reativey inexpensive to produce yet offer very high temperature accuracy and various software controed outputs. For exampe, a micro controer system utiizing remote thermistor sensors can monitor and contro the temperature in severa ocations in an office buiding. For this case, the micro controer is comprised of a buit-in microprocessor, anaog to digita converter, RAM and severa digita inputs/outputs. The compete system Figure 6 utiizes the micro controer, mutipexer, EPROM, digita dispay, keypad and dispay driver. Figure 6: Micro Controer System The micro controer is programmed in assember anguage. The temperature measurement is cacuated within the micro controer using the resistance versus temperature agorithm and the a, b and c, constants for the specific thermistor resistance and curve materia. Refer to the Steinhart Equation on page 5. An aternative method to convert the thermistor resistance to temperature is to program a ook-up tabe in EPROM. After programming, the micro controer tes the mutipexer to send back temperature data from a particuar zone (room in the office buiding) and converts the resistance of the thermistor into a temperature reading. The micro controer can then turn on or off the heating or air conditioning systems in a specific zone. The thermistor/micro controer system can be used for security, temperature contro, monitoring activities and many other appications. The possibiities are endess. 29

31 Appication Notes Temperature Compensation Figure 7: Temperature Compensation NTC thermistors can be used to compensate for the temperature coefficient response of various components such as crysta osciators, mechanica meters and infrared LEDs. A thermistor/ resistor network Figure 7 is paced in series with a PTC component requiring compensation. The resistor vaues are seected to provide the proper NTC sope to offset the PTC component. The net effect is a constant circuit response that is independent of temperature. Sef-Heat Sensing Appications To sef-heat a thermistor, it must be subjected to power eves that raise the thermistor s body temperature above the environmenta surroundings. Sef-heat appications incude the sensing of iquid, air eve, and fow rates. This appication is dependent on the fact that the environment surrounding a thermistor directy affects the amount of power the thermistor can dissipate. For exampe, submerged in iquid, a thermistor can typicay dissipate 500% to 600% more power than it can air. Figure 8: Sef-Heat Appications Therefore, a thermistor being sef-heated in air is abe to dissipate much more power when transferred to a fuid environment. This increase in power dissipation generates a significant increase in resistance. It is this change in resistance, which makes it possibe to sense the fuid eve. A simpe iquid eve contro system can be designed by putting a thermistor in series with a coi Figure 8, which operates a vave that reeases the iquid in the tank. The thermistor is paced in the tank and operated in a sef-heat mode. In air, the thermistor s resistance is ow and aows enough current fow to energize the reay coi and keep the reay contact cosed. When the fuid eve in the tank surrounds the thermistor, its resistance increases and de-energizes the reay, which opens a vave and reeases the fuid. As the fuid is reeased from the tank, the thermistor s resistance decreases and the reay coi energizes and coses the vave. Fue injection in automobies utiize the thermistor in the sef-heat mode in order to propery contro the air/fue mixture. Forced air heaters may use the NTC thermistor in the sef-heat mode in order to maintain proper air fow characteristics. This technoogy is utiized to monitor the fow rate and eve of air and fuids in a variety of appications. 04/10-mb

32 8780 Technoogy Way Reno, NV (800) (775) FAX (775) E-mai: THERMOSTATS THERMISTORS ELECTRONIC CONTROLS CONTROL KNOBS DIGITAL PANEL METERS AEROSPACE AUTOMOTIVE BATTERY PACKS COMMUNICATIONS