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

[Product_Support]

Issue

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

Product Line

TAC INET

Environment

• 7716
• 7718
• 7728
• 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 upper board 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

For the look up table to the 7756 lower board, see 10k Thermistor Look Up Table for an I/Net 7756 (lower board).