SMARTEC B.V.
Humidity sensor : SMTHS10
Version : 1.0
Date : September 2000
- 1 -
Preliminary Specifications
MOST IMPORTANT FEATURES
*
Linear 0 - 100 % RH
*
High Performance
*
Long Term Stability
*
Close tolerances
*
Reliable construction
and
*
Very low cost
TYPICAL APPLICATIONS
*
Airconditioners
*
Climate control for green houses
*
Storage and warehouses
*
Meteorological applications
*
Food processing
*
Room comfort control
*
Medical applications
*
and many more
PRODUCT HIGHLIGHTS
1
The Smartec capacitance humidity sensor measures from 0 to 100 % RH. In many
applications 100 % RH and condensation may occur. This condensation has no effect on
the performance of the Smartec humidity sensor.
2
Linearity. The Smartec humidity sensors has a linear capacitance change from 0 % to
100% RH within a band of 2%.
3
Due to this and the production technology on silicon substrate we can offer now a
humidity sensor at a price level that will allow measurement of humidity where the
traditional humidity sensors are to expensive or to unreliable.
4
Due to its robust construction the response time is a little slower as should be. Therefor
we do not recommend the use of the sensor for applications where a very high
speed of response is required.
PRODUCT DESCRIPTION
The Smartec humidity sensor is a two terminal capacitor which increase in value as water
molecules are absorbed into its active polymer dielectric. The capacitor plates consists of a
base plate and a water permeable platinum top plate. The sensor will be delivered with gold-
plated lead wires attached. Besides the active dielectric, polymers give protection to the base
plate, prevent polarisation and pinholing and generally ruggedise the sensor so that it can be used
in a wide range of hostile environments
SMARTEC B.V.
Humidity sensor : SMTHS10
Version : 1.0
Date : September 2000
- 2 -
SPECIFICATION
Electrical:
Operating humidity range
0 - 100 %RH noncondensing
Operating temperature range
-40 120 C
Capacitance value @ 25 C, 60 %RH, 100 KC
240 pF 15 %
Capacitance range over 0-100 % RH
40 pF 10 %
Advised frequency range
10-100 Kc
Temperature dependency
-0.15% RH/C
Response time top 90 %
60 s. typ.
Linearity
2% RH
Stability over time(12 month)
3 % RH
Maximum Voltage(no DC!)
5 V AC
Storage
Humidity range
0 100 %RH
Temperature
-20 85 C
UNDERSTANDING THE SPECIFICATIONS
The measuring of humidity is difficult. Generally the humidity in air is measured as the fraction
of the maximum amount of water that air can absorbed at a certain temperature. At
atmospheric conditions and a given temperature this fraction can vary between 0 (absolute dry)
and 100% (the point where condensation will begin to form). This relative humidity is only valid
at a certain temperature and atmospheric pressure. Therefor it is important that a humidity sensor
should not be affected by either temperature or pressure. Many sensing techniques, such as
mechanical devices and resistive type sensors are temperature dependent and even the wet and
dry bulb is pressure dependent.
TOLERANCE.
The specified tolerance is the tolerance of the capacitor at 60% RH. This tolerance can be
considered as an effect of the production technology. When the capacitor is f.i. 2 % to high
(@ 0% RH) also the sensitivity will be around 2% to high.
LINEARITY.
The linearity is considered as the maximum deviation from a straight line between 0% RH and
100% RH. In the condensing area some drift can be expected; but this drift is reversible. The
device is resistant against submerge in water.
SMARTEC B.V.
Humidity sensor : SMTHS10
Version : 1.0
Date : September 2000
- 3 -
PACKAGE OUTLINE AND SOLDERING PRECAUTIONS.
Soldering.
The products is special suited for soldering by hand. Special precautions has to be taken:
-
a heat dissipater(pincers) has to be placed between pins during operation,
-
soldering temperature must be below 350 C
-
soldering time must be below 3 seconds.
Outline drawing
Ordering information
SMTHS10
Smartec Humidity sensor
0.5
1.0
2.80
3.6
22.5
15.5
3.0
Humidity Sensor type SMTHS10
All sizes in mm
Leads : gold pleated
Thickness 0.4 mm
0.7
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