10k Thermistor Look Up Tables for a 7716, 7718, 7728 and a 7756 (upper board)

Issue

Tables needed for linearizing a 10K thermistors for an I/Net 7716, 7718, 7728 and 7756 (upper board)

Product Line

TAC I/NET

Environment

7716, 7718, 7728 and 7756

Cause

Thermistors require the use of a look up table to linearize the data.

Resolution

Thermistor Inputs on PCU's 7716, 7718, 7728 and the upperboard of a 7756

  1. Enter the Temperature data in °C (First Column - 31 entries)
  2. Enter the corresponding resistance data in Ohms (Second column - 31 entries)
  3. Enter the dissipation constant in milliwatts per °C: 2
  4. Low Temperature :     -22.11°F       -30.06°C
  5. High Temperature:    247.92°F      119.95°C
  6. Point Value in °F:   M=0.065942      b=-22.11377
  7. Point Value in °C:  M=0.03663447  b=-30.063207

Look Up Table:

°C Ohms Current Self Htg Adj °C Adj °F VDC Counts Adj Cts
120 389 0.000481 0.045052 119.95 247.92 0.1872172 153 4095
100 680 0.000468 0.074521 99.93 211.87 0.3183521 261 3548
90 917 0.000458 0.096177 89.90 193.83 0.4199872 344 3275
80 1258 0.000444 0.12407 79.88 175.78 0.5587138 458 3001
70 1753 0.000425 0.158633 69.84 157.71 0.745767 611 2727
60 2489 0.0004 0.199471 59.80 139.64 0.9964769 816 2453
55 3045 0.000383 0.223671 54.78 130.60 1.1671138 956 2316
50 3602 0.000368 0.243359 49.76 121.56 1.32407 1084 2179
45 4368 0.000348 0.264484 44.74 112.52 1.5200445 1245 2042
40 5326 0.000326 0.283435 39.72 103.49 1.7375701 1423 1905
35 6691 0.0003 0.300218 34.70 94.46 2.0043736 1642 1768
30 8056 0.000277 0.308878 29.69 85.44 2.2308374 1827 1631
28 8777 0.000266 0.311174 27.69 81.84 2.3371678 1914 1576
26 9572 0.000255 0.312351 25.69 78.24 2.4453301 2003 1522
25 10000 0.00025 0.3125 24.69 76.44 2.5 2048 1495
24 10450 0.000244 0.312349 23.69 74.64 2.5550122 2093 1467
22 11420 0.000233 0.311127 21.69 71.04 2.665733 2183 1413
20 12490 0.000222 0.308669 19.69 67.44 2.7767897 2274 1358
18 13680 0.000211 0.304953 17.70 63.85 2.8885135 2366 1304
16 15000 0.0002 0.3 15.70 60.26 3 2457 1249
14 16470 0.000189 0.29383 13.71 56.67 3.1110691 2548 1195
12 18090 0.000178 0.286579 11.71 53.08 3.2200071 2637 1140
10 19900 0.000167 0.278241 9.72 49.50 3.3277592 2725 1086
8 21920 0.000157 0.268921 7.73 45.92 3.433584 2812 1032
6 24180 0.000146 0.258715 5.74 42.33 3.5371562 2897 977
0 32660 0.000117 0.224329 -0.22 31.60 3.8279419 3135 815
-4 36200 0.000108 0.211999 -4.21 24.42 3.9177486 3209 706
-10 55340 0.0000765 0.162028 -10.16 13.71 4.234772 3468 543
-14 69000 0.0000633 0.138199 -14.14 6.55 4.3670886 3577 435
-20 97130 0.0000467 0.105789 -20.11 -4.19 4.5332773 3713 272
-30 177200 0.0000267 0.063207 -30.06 -22.11 4.732906 3876 0

This spreadsheet is for a thermistor rated at 10,000 ohms at 25°C.

  1. Install a 10K Ohm Resistor in the "B" terminal (consult the TCON for the controller you are using for details)
  2. This look up table program is based on using 31 entries
  3. The data points do not have to be evenly spaced

Click here to download this in pdf format.

For the look up table to the 7756 lower board, see Lessons Learned Article #7212.