Surface Mount Thermistors-KR/TR/STC Series

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RTI manufactures precision resistance-temperature SMD thermistors. Standard values from 250 ohms to 150,000 ohms are available. As with RTI’s disc and chip thermistors, SMD thermistors are suitable for temperature sensing applications over a wide range of resistance values and temperature coefficients. SMD’s operating temperature range is from -55°C to +150°C. Dissipation constant is 2mW/°C, with a maximum power rating of 250mW @ 25°C.

Applications

Most semiconductors and the circuits comprised of them exhibit a positive temperature coefficient. NTC thermistors are well suited for compensating these responses to temperature changes. It is important to match the temperature of the compensating NTC thermistor to that of the component responsible for the temperature response.

RTI’s SMD temperature measurement NTC sensors can operate over a wide temperature range (-55 to +150°C). They are stable throughout a long lifetime, and are small and comparatively inexpensive. Typically, they have negative temperature coefficients between -3.3 and -4.7%/°C at 25°C. RTI’s SMD style thermistors are used in many applications that require a high degree of accuracy and reliability.

Features:

  • Standard Sizes
  • High Sensitivity
  • Accurate & Stable
  • Wide Ohmic Value Range
  • Fast Thermal Response Time

Popular Applications:

  • LED Control
  • Temperature Compensation
  • Power Transistor Stabilization
  • Temperature Measurement & Control

Selection Considerations for SMD NTC Devices

  • To determine the nominal resistance value of a thermistor at a specified temperature, multiply its RT/R25 value for the desired temperature and R-T curve from the table on NTC Resistance/Temperature Conversion Tables by its nominal resistance value at 25°C. As an example, the nominal resistance value at 80°C for a thermistor with the part number KR0805B103K is 10,000 times 0.157, the RT/R25 value in the R-T Curve “B” in the table under NTC Resistance/Temperature Conversion Tables.
  • Standard resistance tolerances at 25°C for RTI’s SMD thermistors is ±10% and is indicated in its part number by the addition of the suffix K. To determine the resistance value at other than 25°C, add the appropriate DEV value from the NTC resistance/Temperature Conversion Tables to its resistance tolerance at 25°C. For example, the resistance tolerance at 80°C for a thermistor with part number KR0805B103K is ±10% ±3.0%, the DEV value from the R-T Curve “B” Table.
  • Although standard sizes, resistance values and tolerances are listed on SMD Standard Products and Sizes, custom sizes, resistance values and tolerances are available depending on the application and volume requirements.

Consideration Notes:

  • Calculate the DEV for R@T
  • Review Power Dissipation
  • Determine Required Accuracy
  • Review Power Dissipation
  • Select Required Resistance Values & Temperature Coefficient

KR SERIES

KR Series Surface Mount Thermistors

Configuration Options:

  • Standard EIA Sizes Available
  • Silver Palladium Terminations
  • Bulk or Tape and Reel Packaging
  • Two-Sided or Wraparound Terminations

KR Series Size Chart

Size 0805 1206
Units Inches Millimeters Inches Millimeters
W 0.049 ±0.008 1.240 ±0.200 0.063 ±0.008 1.600 ±0.200
H 0.051 Maximum 1.300 Maximum 0.059 Maximum 1.500 Maximum
L 0.079 ±0.008 2.000 ±0.200 0.126 ±0.008 3.200 ±0.200
B 0.008 Minimum 0.200 Minimum 0.008 Minimum 0.200 Minimum

KR Series Product Chart

Part Number Size 0805 Part Number Size 1206 Resistance @ 25°C ±10% (Ohms) Temperature Coefficient (@25°C)
KR0805A251K KR1206A251K 250 -3.3%/°C
KR0805A501K KR1206A501K 500 -3.3%/°C
KR0805J102K KR1206J102K 1.0K -3.5%/°C
KR0805J252K KR1206J252K 2.5K -3.5%/°C
KR0805B502K KR1206B502K 5.0K -3.9%/°C
KR0805B103K KR1206B103K 10K -3.9%/°C
KR0805C203K KR1206C203K 20K -4.4%/°C
KR0805C253K KR1206C253K 25K -4.4%/°C
KR0805C503K KR1206C503K 50K -4.4%/°C
KR0805W104K KR1206W104K 100K -4.7%/°C
KR0805W154K KR1206W154K 150K -4.7%/°C

KR Series Ordering Information

KR = Model 0805 =Size A = R-T Curve 251 = Resistance* K = Tolerance** X = Termination***

* Resistance value: First two digits are resistance value, third is the number of zeroes. Example: 251 = 250 ohms.

** Tolerances available: K = ±10% and J= ±5%.

***Terminations: No letter = Palladium Silver (Consult factory for optional terminations)

STC SURFACE MOUNT AND NTC CHIP THERMISTORS

 

Well suited for Temperature Measurement, Compensation and Control. stc-1-439

  • Fan Motors
  • Fluid Levels
  • Hybrid Circuits
  • Robotic Assemblies
  • Temperature Sensors used in a wide range of end products

STC Surface Mount & NTC Chip Thermistor Key Benefits  

  • ROHS Compliant
  • Wide Range TCR Values
  • Precision tolerance to 1%
  • Fast Thermal Response Time
  • High Accuracy Temperature Measurement
  • Great alternative to thermocouples in precision circuits
  • Available in sizes as small as 0.50 mm by 0.50 mm by 0.43 mm
  • Wide range of resistance values at at 25 °C from 100 Ω to 5000 Ω
  • High-Temperature Operation to + 150 °C

*For increased reliability, the device’s electrode surface is available in gold to prevent oxidation

STC Device Specification Table:
Series Resistance @ 25 °C (Ω) Size (mm) Resistance ratio Beta (°K)
STC0134-X 100 to 680 0.58 x 0.58 x 0.76 to 1.0 x 1.0 x 1.7 5.3 (±5%) 3000
STC0138-X 700 to 5000 0.89 x 0.89 x 0.97 to 1.3 x 1.3 x 1.6 6.9 (±3%) 3523
STC0143 500 0.50 x 0.50 x 0.43 5.3 (±3%) 3000
STC0144-X 150 to 500 0.64 x 0.64 x 0.33 to 0.76 x 0.76 x 0.28 5.3 (±3%) 3000

TR SERIES

 

Standard EIA Sizes Available

Nickel Barrier Terminations

Bulk or Tape and Reel Packaging

Two-Sided or Wraparound Terminations

TR Size Chart

Size

0603

0805

Units Inches Millimeters Inches Millimeters
Length 0.063  ±0.006 1.60  ±0.150 0.080  ±0.008 2.00  ±0.20
Width 0.0315  ±0.006 0.80  ±0.15 0.050  ±0.004 1.25  ±0.10
Height 0.020  ±0.004 0.50  ±0.10 0.020  ±0.004 0.50  ±0.10
Termination 0.0012  ±0.0079 0.30  ±0.2 0.0016  ±0.008 0.40  ±0.20

 

 

 

 

 

 

 

 

TR Standard Product Chart

Part Number  Size 0603 Part Number  Size 0805 Resistance @ 25°C  ±10% (Ohms) Temperature  Coefficient @25°C)
TR0603A251K TR0805A251K 250 -3.3%/°C
TR0603A501K TR0805A501K 500 -3.3%/°C
TR0603J102K TR0805J102K 1.0K -3.5%/°C
TR0603J252K TR0805J252K 2.5K -3.5%/°C
TR0603B502K TR0805B502K 5.0K -3.9%/°C
TR0603B103K TR0805B103K 10K -3.9%/°C
TR0603C203K TR0805C203K 20K -4.4%/°C
TR0603C253K TR0805C253K 25K -4.4%/°C
TR0603C503K TR0805C503K 50K -4.4%/°C
TR0603W104K TR0805W104K 100K -4.7%/°C
TR0603W154K TR0805W154K 150K -4.7%/°C

TR Series Ordering Information

TR = Model    0805 = Size   A = R-T Curve   251 =  *Resistance   K = **Tolerance   X = ***Termination

*Resistance value: First two digits are resistance value, third is the number of zeroes. Example: 251 = 250 ohms. 

** Tolerances available: K =±;10% and J=±;5%. 

***Terminations: No letter = Nickel Barrier (Consult factory for optional terminations). For tape and reel add suffix -T/R

 

TERMINOLOGY FOR SMD TEMPERATURE MEASUREMENT

  • D.C. – The dissipation constant is the ratio, normally expressed in milliwatts per degree C (mw/°C), at a specified ambient temperature, of a change in power dissipated in a thermistor to the resultant change in body temperature.
  • T.C. – The thermal time constant is the time required for a thermistor to change 63.2% of the total difference between its initial and final body temperature when subjected to a step function change in temperature under zero-power conditions and is normally expressed in seconds (S).
  • Alpha (ß) or Temperature Coefficient of Resistance- The temperature coefficient of resistance is the ratio at a specified temperature, T, of the rate of change of zero-power resistance with temperature to the zero-power resistance of the thermistor. The temperature coefficient is commonly expressed in percent per degree C (%/°C).

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NTC RESISTANCE / TEMPERATURE CONVERSION TABLE

Temperature °C R-T Curve A R-T Curve B R-T Curve C R-T Curve J R-T Curve W
RT/R25 DEV RT/R25 DEV RT/R25 DEV RT/R25 DEV RT/R25 DEV
-60 43.0 75.0 6.6 140.5 6.6 52.5
-55 31.9 54.1 6.1 96.4 6.1 39.0
-50 24.3 39.7 5.6 67.0 5.6 29.2 18.5
-45 18.6 29.2 5.2 47.2 5.2 22.1 17.0
-40 14.4 7.6 21.7 4.7 33.7 4.7 16.9 15.4 40.2 7.6
-35 11.3 6.9 16.4 4.3 24.3 4.3 13.0 14.0 28.6 6.9
-30 8.93 6.2 12.5 3.8 17.7 3.8 10.1 12.5 20.6 6.2
-25 7.10 5.6 9.58 3.4 13.0 3.4 7.90 11.2 15.0 5.6
-20 5.69 5.0 7.42 3.0 9.71 3.0 6.24 9.9 11.0 5.0
-15 4.56 4.4 5.75 2.6 7.30 2.6 4.96 8.7 8.18 4.4
-10 3.68 3.7 4.50 2.2 5.53 2.2 3.97 7.4 6.12 3.7
-5 2.99 3.1 3.55 1.9 4.23 1.9 3.20 6.2 4.62 3.1
0 2.45 2.5 2.82 1.5 3.27 1.5 2.60 5.0 3.51 2.5
5 2.02 2.0 2.26 1.2 2.54 1.2 2.12 3.9 2.69 2.0
10 1.68 1.6 1.83 0.8 1.99 0.8 1.74 2.7 2.08 1.6
15 1.42 1.1 1.48 0.5 1.57 0.5 1.44 1.6 1.62 1.1
20 1.18 0.6 1.22 0.2 1.25 0.2 1.20 0.5 1.27 0.6
25 1.00 0.0 1.00 0.0 1.00 0.0 1.00 0.0 1.00 0.0
30 0.854 0.6 0.828 0.4 0.806 0.4 0.841 1.4 0.794 0.6
35 0.732 1.1 0.689 0.7 0.653 0.7 0.710 2.3 0.635 1.1
40 0.628 1.6 0.576 1.0 0.533 1.0 0.602 3.2 0.510 1.6
45 0.537 2.0 0.482 1.3 0.437 1.3 0.513 4.3 0.413 2.0
50 0.464 2.5 0.406 1.5 0.360 1.5 0.439 5.0 0.336 2.5
55 0.403 3.0 0.343 1.8 0.299 1.8 0.377 5.9 0.275 3.0
60 0.350 3.4 0.292 2.0 0.249 2.0 0.326 6.7 0.226 3.4
65 0.305 3.8 0.247 2.3 0.208 2.3 0.282 7.5 0.187 3.8
70 0.267 4.2 0.212 2.5 0.175 2.5 0.245 8.2 0.155 4.2
75 0.236 4.6 0.182 2.8 0.148 2.8 0.214 9.0 0.129 4.6
80 0.208 4.9 0.157 3.0 0.126 3.0 0.188 9.8 0.108 4.9
85 0.183 5.3 0.137 3.2 0.107 3.2 0.165 10.5 0.0912 5.3
90 0.163 5.6 0.120 3.4 0.0916 3.4 0.146 11.2 0.0771 5.6
95 0.145 6.0 0.105 3.6 0.0787 3.6 0.129 11.9 0.0654 6.0
100 0.130 6.3 0.0920 3.8 0.0679 3.8 0.114 12.6 0.0557 6.3
105 0.117 6.7 0.0812 4.0 0.0588 4.0 0.102 13.3 0.0476 6.7
110 0.105 7.0 0.0723 4.2 0.0511 4.2 0.0908 13.9 0.0408 7.0
115 0.0943 7.3 0.0641 4.4 0.0445 4.4 0.0813 14.4 0.0351 7.3
120 0.0852 7.6 0.0569 4.6 0.0389 4.6 0.0730 14.9 0.0303 7.6
125 0.0771 7.9 0.0508 4.8 0.0342 4.8 0.0657 15.6 0.0263 7.9
130 0.0700 8.2 0.0455 4.9 0.0301 4.9 0.0593 16.3 0.0228 8.2
135 0.0636 8.4 0.0408 5.1 0.0265 5.1 0.0536 17.0 0.0199 8.4
140 0.0579 8.6 0.0368 5.3 0.0235 5.3 0.0486 17.6 0.0173 8.6
145 0.0529 9.0 0.0332 5.4 0.0208 5.4 0.0442 18.0 0.0152 9.0
150 0.0483 9.3 0.0300 5.5 0.0185 5.5 0.0402 18.4 0.0133 9.3

NTC RESISTANCE / TEMPERATURE CURVE CHARACTERISTICS


R-T Curve

A B C J W
Temperature Coefficient @ 25°C -3.3%/°C -3.9%/°C -4.4%/°C -3.5%/°C -4.7%/°C
Beta, ß 3000°K 3530°K 3965°K 3200°K 4250°K
R0°C/R50°C 5.3±5% 6.9±3% 9.1±3% 5.9±5% 10.45±5%
R25°C/R125°C 13.0 19.8 29.4 15.2 38.0