ACCU-CURVE™ 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 and Temperature Coefficient
  • Review Power Dissipation
  • Select Temperature Range
  • Review Thermal Time Constant

 

 

accu curve

           

 

ACCU-CURVE™ Specifications

Part Number

R @ 25°C

Accuracy in °C

Beta 25/85

DC @ MW/OC

Time Constant

Coating

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ACC-001 2252 ± 0.2°C 3988 1 mw/°C 7 sec  Black Epoxy  ACC-001
ACC-011 2252 ± 0.5°C 3988 1 mw/°C 7 sec  Black Epoxy  ACC-011
ACC-021 2252 ± 1.0°C 3988 1 mw/°C 7 sec  Black Epoxy  ACC-021
ACC-004 10,000 ± 0.2°C 3988 1 mw/°C 7 sec  Black Epoxy  ACC-004
ACC-014 10,000 ± 0.5°C 3988 1 mw/°C 7 sec  Black Epoxy  ACC-014
ACC-024 10,000 ± 1.0°C 3988 1 mw/°C 7 sec  Black Epoxy  ACC-024
ACW-005 30,000 ± 0.2°C 4240 1 mw/°C 7 sec  Black Epoxy  ACW-005
ACW-015 30,000 ± 0.5°C 4240 1 mw/°C 7 sec  Black Epoxy  ACW-015
ACW-025 30,000 ± 1.0°C 4240 1 mw/°C 7 sec  Black Epoxy  ACW-025
ACW-007 100,000 ± 0.2°C 4240 1 mw/°C 7 sec  Black Epoxy  ACW-007
ACW-017 100,000 ± 0.5°C 4240 1 mw/°C 7 sec  Black Epoxy  ACW-017
ACW-027 100,000 ± 1.0°C 4240 1 mw/°C 7 sec  Black Epoxy  ACW-027

 

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Application 

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™.

ACCU-CURVE™Specifications

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

 

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
-40 75,780 100,950 168,250 336,500 1,204,600 2,007,700 4,015,500
-30 39,860 53,100 88,500 177,000 619,200 1,032,000 2,064,000
-20 21,860 29,121 48,535 97,070 331,030 551,720 110,3400
-10 12,460 16,599 27,665 55,330 183,560 305,940 611,870
0 7,352.8 9,795.0 16,325 32,650 105,310 175,510 351,020
10 4,481.5 5,970.0 9,950.0 19,900 62,354 103,920 207,850
20 2,812.8 3,747.0 6,245.0 12,490 38,022 63,370 126,740
25 2,252.0 3,000.0 5,000.0 10,000 30,000 50,000 100,000
30 1,814.4 2,417.1 4,028.5 8,057.0 23,827 39,711 79,422
40 1,199.6 1,598.1 2,663.3 5,327.0 15,314 25,524 51,048
50 811.40 1,080.9 1,801.5 3,603.0 10,077 16,795 33,591
60 560.30 746.40 1,244.0 2,488.0 6,777.1 11,295 22,590
70 394.55 525.60 876.00 1,752.0 4,650.5 7,750.9 15,502
80 282.63 376.50 627.50 1,255.0 3,251.2 5,418.7 10,837
90 206.13 274.59 457.65 915.30 2,312.3 3,853.9 7,707.7
100 152.75 203.49 339.15 678.30 1,670.8 2,784.6 5,569.3
110 114.92 153.09 255.15 510.30 1,224.9 2,041.5 4,082.9
120 87.671 116.79 194.65 389.30 909.99 1,516.7 3,033.3
130 67.770 90.279 150.47 300.93 684.31 1,140.5 2,281.0
140 52.983 70.581 117.64 235.27 520.30 867.16 1,734.3
150 41.881 55.791 92.985 185.97 399.56 665.94 1,331.9
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. °C RT/R25
0 3.265
1 3.103
2 2.950
3 2.805
4 2.669
5 2.539
6 2.417
7 2.301
8 2.192
9 2.088
10 1.990
11 1.897
12 1.809
13 1.725
14 1.646
15 1.571
16 1.500
17 1.432
18 1.368
19 1.307
20 1.249
21 1.194
22 1.142
23 1.092
24 1.045
25 1.000
26 0.9573
27 0.9167
28 0.8777
29 0.8407
30 0.8057
31 0.7723
32 0.7403
33 0.7097
34 0.6807
35 0.6530
TEMP. °C RT/R25
36 0.6267
37 0.6017
38 0.5777
39 0.5547
40 0.5327
41 0.5117
42 0.4917
43 0.4727
44 0.4543
45 0.4370
46 0.4200
47 0.4040
48 0.3890
49 0.3743
50 0.3603
51 0.3467
52 0.3340
53 0.3217
54 0.3099
55 0.2986
56 0.2878
57 0.2774
58 0.2675
59 0.2579
60 0.2488
61 0.2400
62 0.2316
63 0.2235
64 0.2157
65 0.2083
66 0.2011
67 0.1942
68 0.1876
69 0.1813
70 0.1752
   
TEMP. °C RT/R25
0 3.5102
1 3.3264
2 3.1532
3 2.9899
4 2.8360
5 2.6908
6 2.5539
7 2.4246
8 2.3026
9 2.1873
10 2.0785
11 1.9756
12 1.8784
13 1.7865
14 1.6995
15 1.6173
16 1.5395
17 1.4658
18 1.3961
19 1.3300
20 1.2674
21 1.2081
22 1.1519
23 1.0985
24 1.0480
25 1.0000
26 0.9545
27 0.9113
28 0.8702
29 0.8313
30 0.7942
31 0.7590
32 0.7256
33 0.6938
34 0.6636
35 0.6348
TEMP. °C RT/R25
36 0.6074
37 0.5814
38 0.5566
39 0.5330
40 0.5105
41 0.4891
42 0.4686
43 0.4492
44 0.4306
45 0.4129
46 0.3961
47 0.3800
48 0.3646
49 0.3499
50 0.3359
51 0.3225
52 0.3098
53 0.2976
54 0.2859
55 0.2748
56 0.2641
57 0.2539
58 0.2442
59 0.2348
60 0.2259
61 0.2174
62 0.2092
63 0.2014
64 0.1939
65 0.1867
66 0.1798
67 0.1732
68 0.1669
69 0.1608
70 0.1550
   
To determine the nominal resistance 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?