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OM-USB-5203 User's Guide
Specifications
24
Thermistor measurement accuracy
The error shown in Table 7 below does not include errors of the sensor itself. The sensor linearization is
performed using a Steinhart-Hart linearization algorithm. These specs are for one year while operating the
device between 15 °C and 35 °C. The specification does not include lead resistance errors for 2-wire thermistor
connections. Please contact your sensor supplier for details on the actual sensor error limitations.
Total thermistor resistance on any given channel pair must not exceed 180
kΩ (refer to Table 8 below).
Table 7. Thermistor measurement accuracy specifications
Thermistor
Temperature Range (°C)
Maximum Accuracy Error (°C)
I
x+
= 10 µA
2252
Ω
–40 to120
±0.05
3000
Ω
–40 to120
±0.05
5000
Ω
–35 to120
±0.05
10000
Ω
–25 to120
±0.05
30000
Ω
–10 to120
±0.05
Typical resistance values at various temperatures for supported thermistors are shown in Table 8 below.
The device cannot measure resistance values
greater than 180 kΩ in thermistor mode. The 180 kΩ resistance
limit includes the total resistance across the current excitation (Ix+/Ix–) pins, which is the sum of the thermistor
resistance and the lead resistances.
For accurate three-wire compensation, the individual lead resistances connected to the Ix+/Ix– pins must be of
equal value.
Table 8. Typical thermistor resistance specifications
Temp
(°C)
2252 Ω
thermistor
3000 Ω thermistor 5 kΩ thermistor 10 kΩ thermistor 30 kΩ thermistor
–40
76 kΩ
101 kΩ
168 kΩ
240 kΩ
885 kΩ
–35
55 kΩ
73 kΩ
121 kΩ
179 kΩ
649 kΩ
–30
40 kΩ
53 kΩ
88 kΩ
135 kΩ
481 kΩ
–25
29 kΩ
39 kΩ
65 kΩ
103 kΩ
360 kΩ
–20
22 kΩ
29 kΩ
49 kΩ
79 kΩ
271 kΩ
–15
16 kΩ
22 kΩ
36 kΩ
61 kΩ
206 kΩ
–10
12 kΩ
17 kΩ
28 kΩ
48 kΩ
158 kΩ
–5
9.5 kΩ
13 kΩ
21 kΩ
37 kΩ
122 kΩ
0
7.4 kΩ
9.8 kΩ
16 kΩ
29 kΩ
95 kΩ