ACCU-CURVE™ Precision Thermistors

Ametherm manufactures precision resistance-temperature matched ACCU-CURVE™ thermistors. These devices offer interchangeability over a broad temperature range and eliminate the need to individually calibrate or provide circuit compensation for part variability. Accurate temperature measurement to ±0.2°C is available over the 0°C to 70°C temperature range. Standard ohmic values at 25°C range from 2,252 to 100,000 ohms.

ACCU-CURVE™ Selection Considerations

  • Determine Resistance Value & Temperature Coefficient
  • Review Power Dissipation
  • Select Temperature Range
  • Review Thermal Time Constant

 

 

accu-curve product

 

Applications

There are numerous ways of measuring temperature electronically. Improvements in thermistor technology, coupled with the introduction of integrated circuitry, have made precision temperature measurement systems very cost effective

Microprocessors, A/D converters, interface electronics and displays are readily available. Circuit designs with built-in thermistor resistance-temperature algorithms have gained wide spread acceptance in precision temperature metrology.

Ametherms’s ACCU-CURVE™ style thermistors are used in many applications that require a high degree of accuracy and reliability. They commonly perform temperature sensing, control, and compensation for medical, industrial, and automotive applications. 

Interchangeable ACCU-CURVE™ NTC thermistors are usually selected when a high degree of measurement accuracy is required over a wide temperature range. By modifying the Alpha equation the resistance and temperature tolerances can be calculated for various temperature intervals.

Because thermistors are non-linear with respect to their resistance-temperature characteristics, Alpha therefore is non-linear across their resistance-temperature range. As an example, a thermistor material curve with an Alpha of -4.4%/°C @ 25°C will have an Alpha of -3.8%/°C @ 50°C. For practical applications we recommend that the standardized R/T curves be used.

Ametherm ACCU-CURVE™ thermistors can dissipate 1mW/°C. As a result, the possibility of error induced by excessive current flow, which would defeat the level of accuracy these devices are capable of representing, may exist in some circuits. To prevent this type of error, Ametherm recommends that circuit design engineers select the highest R value their circuit will tolerate for applications > 5 Volts to minimize any self-heating of the thermistor device. Refer to the ACCU-CURVE™ Specifications table for resistance values and temperature tolerances.

Ametherm offers two standard R/T curves, “C” & “W”, with temperature coefficients of resistance of -4.4%/°C and -4.7%/°C, and Beta (ß) values of 3965°K and 4250°K. To determine the nominal resistance value of a thermistor at a specified temperature, multiply its resistance at 25°C value by the corresponding RT/R25 value for the desired temperature and applicable R-T curve from the ACCU-CURVE™.

Selection Considerations for NTC ACCU-CURVE™ Devices Interchangeable ACCU-CURVE™ NTC thermistors are usually selected when a high degree of measurement accuracy is required over a wide temperature range. By modifying the Alpha equation the resistance and temperature tolerances can be calculated for various temperature intervals.

 
 

ACCU-CURVE™Specifications

Resistance
@ 25° C (ohms)
Temperature Tolerance from 0° C to 70° CColor
Code
±0.2° C±0.5° C±1.0° C
Part NumberPart NumberPart Number
2,252ACC-001ACC-011ACC-021Brown
3,000ACC-002ACC-012ACC-022Red
5,000ACC-003ACC-013ACC-023Orange
10,000ACC-004ACC-014ACC-024Yellow
30,000ACW-005ACW-015ACW-025Green
50,000ACW-006ACW-016ACW-026Blue
100,000ACW-007ACW-017ACW-027Violet

ACCU-CURVE™Resistance/Temperature Table

TEMP (°C)“C” CURVES“W” CURVES
2,252
ohm s
@ 25°C
3,000
ohms
@ 25°C
5,000
ohm s
@ 25°C
10,000
ohm s
@ 25°C
30,000
ohm s
@ 25°C
50,000
ohm s
@ 25°C
100,000
ohms
@ 25°C
-4075,780100,950168,250336,5001,204,6002,007,7004,015,500
-3039,86053,10088,500177,000619,2001,032,0002,064,000
-2021,86029,12148,53597,070331,030551,720110,3400
-1012,46016,59927,66555,330183,560305,940611,870
07,352.89,795.016,32532,650105,310175,510351,020
104,481.55,970.09,950.019,90062,354103,920207,850
202,812.83,747.06,245.012,49038,02263,370126,740
252,252.03,000.05,000.010,00030,00050,000100,000
301,814.42,417.14,028.58,057.023,82739,71179,422
401,199.61,598.12,663.35,327.015,31425,52451,048
50811.401,080.91,801.53,603.010,07716,79533,591
60560.30746.401,244.02,488.06,777.111,29522,590
70394.55525.60876.001,752.04,650.57,750.915,502
80282.63376.50627.501,255.03,251.25,418.710,837
90206.13274.59457.65915.302,312.33,853.97,707.7
100152.75203.49339.15678.301,670.82,784.65,569.3
110114.92153.09255.15510.301,224.92,041.54,082.9
12087.671116.79194.65389.30909.991,516.73,033.3
13067.77090.279150.47300.93684.311,140.52,281.0
14052.98370.581117.64235.27520.30867.161,734.3
15041.88155.79192.985185.97399.56665.941,331.9
 
The ACCU-CURVE™ device can also be supplied with 32 AWG solid Teflon insulated leads of 3, 6, 9 and 12 inches in length. contact Ametherm applications engineering for additional information. Warning: Use Heat sinks when soldering to Thermistor Leads.
 
ACCU-CURVE™Resistance/Temperature Conversion Tables
ACCX-0XX
“C” CURVE
ACWX-0XX
“W” CURVE
TEMP. °CRT/R25
03.265
13.103
22.950
32.805
42.669
52.539
62.417
72.301
82.192
92.088
101.990
111.897
121.809
131.725
141.646
151.571
161.500
171.432
181.368
191.307
201.249
211.194
221.142
231.092
241.045
251.000
260.9573
270.9167
280.8777
290.8407
300.8057
310.7723
320.7403
330.7097
340.6807
350.6530
TEMP. °CRT/R25
360.6267
370.6017
380.5777
390.5547
400.5327
410.5117
420.4917
430.4727
440.4543
450.4370
460.4200
470.4040
480.3890
490.3743
500.3603
510.3467
520.3340
530.3217
540.3099
550.2986
560.2878
570.2774
580.2675
590.2579
600.2488
610.2400
620.2316
630.2235
640.2157
650.2083
660.2011
670.1942
680.1876
690.1813
700.1752
  
TEMP. °CRT/R25
03.5102
13.3264
23.1532
32.9899
42.8360
52.6908
62.5539
72.4246
82.3026
92.1873
102.0785
111.9756
121.8784
131.7865
141.6995
151.6173
161.5395
171.4658
181.3961
191.3300
201.2674
211.2081
221.1519
231.0985
241.0480
251.0000
260.9545
270.9113
280.8702
290.8313
300.7942
310.7590
320.7256
330.6938
340.6636
350.6348
TEMP. °CRT/R25
360.6074
370.5814
380.5566
390.5330
400.5105
410.4891
420.4686
430.4492
440.4306
450.4129
460.3961
470.3800
480.3646
490.3499
500.3359
510.3225
520.3098
530.2976
540.2859
550.2748
560.2641
570.2539
580.2442
590.2348
600.2259
610.2174
620.2092
630.2014
640.1939
650.1867
660.1798
670.1732
680.1669
690.1608
700.1550
  
To determine the nominal resisteance value of a thermistor at a specified temperature, multiply its RT/R25value for the desired temperature and R-T curve from the table above by its nominal resistance at 25 °C.
 

 

 More Information:

 What is an NTC thermistor?

ACCU-Curve Thermistors for Temperature Measurement and Control