M i c r o C h e m i c a l S y s t e m s
P R O D U C T D A T A S H E E T
MiCS-5131 Product Data Sheet
Page 2 of 5
Doc NO: 0178 Rev. B
S e n s o r C h a r a c t e r i s t i c s
Important Precautions:
Please read the following instructions carefully before using the MiCS-5131 sensor described in this
document to avoid erroneous readings and to prevent the device from permanent damage.
•
The sensor must not be wave soldered without protection or exposed to high concentrations of organic solvents,
ammonia, or silicone vapors in order to avoid poisoning the sensitive layer.
•
Heating powers above the specified maximum rating of 120mW can destroy the sensor due to overheating.
•
This sensor is to be placed in a filtered package that protects it against any water or dust projection.
•
For any additional questions, please contact us at:
apps@microchemical.com
Operating Mode:
The recommended mode of operation is a constant power
mode. A heater power of PH = 102 mW is applied. This
causes the temperature of the sensing resistor (RS) to
reach about 450°C.
Detection of ethanol is achieved by measuring the sensing
resistor RS during operation.
Sensor Response:
The sensor response to ethanol in air is represented in
Figure 1. The sensor resistance RS is normalized to the
resistance under air (R0).
Measurement Circuit:
Figure 2 shows the pin connections of the MiCS-5131 gas
sensor. A simple circuit to measure the ethanol level is
proposed in Figure 3. The heating voltage VH is applied to
pins 3 and 1. A load resistor RL is connected in series with
RS to convert the resistance RS to a voltage VS between
pins 2 and 4. RS can then be calculated by the following
expression:
RS = RL /(VCC - VS
)
⋅ VS
RS
1
4
2
3
RH
Pin Number
1
Heater Ground
2
Sensor Pin
3
Heater Power
4
Sensor Pin
Figure 2: Equivalent circuit (top view) of MiCS 5131.
Figure 3: Measurement circuit for ethanol detection.
VS
VCC
VH
Gas
Sensor
RL
GND
1
4
3 2
0.1
1
10
100
1000
Figure 1: RS / R0 as a function of gas concentration
at 50% RH and 25°C.
Ethanol [ppm]
RS/R0
Russian ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
