Si7005
4.2. Relative Humidity Sensor Accuracy
To determine the accuracy of a relative humidity sensor, it is placed in a temperature and humidity controlled
chamber. The temperature is set to a convenient fixed value (typically 30 °C) and the relative humidity is swept
from 20 to 80% and back to 20% in the following steps: 20% – 40% – 60% – 80% – 80% – 60% – 40% – 20%. At
each set-point, the chamber is allowed to settle for a period of 30 minutes before a reading is taken from the
sensor. Prior to the sweep, the device is allowed to stabilize to 50%RH. The solid top and bottom trace in Figure 7,
“Measuring Sensor Accuracy Including Hysteresis,” shows the result of a typical sweep after non-linearity
compensation.
RHAccuracyvs.RHSetͲPoint
5
4
3
Hysteresis
2
1
0
Ͳ1
10
20
30
40
50
60
70
80
90
Ͳ2
Ͳ3
Ͳ4
Ͳ5
%RHSetͲpoint
Figure 7. Measuring Sensor Accuracy Including Hysteresis
Rev. 1.3
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