Figaro TGS2442-B00 TGS 2442 Gas Sensor For Carbon Monoxide Carbon monoxide (Ø x H) 9.2 mm x 12.7 mm TGS2442-B00 データシート
製品コード
TGS2442-B00
Revised 07/07
4
TECHNICAL INFORMATION FOR TGS2442
0
50
100
150
200
250
300
350
400
0
5
10
15
20
Temperature (˚C)
VH pulse width (msec)
Figure 6b - Surface temperature of sensing element
during V
H
pulse cycle
(0msec = start of V
H
pulse cycle)
0.1
1
10
100
0
200
400
600
800
1000
Rs/Ro
Time (msec)
Air
CO 30ppm
CO 300ppm
CO 100ppm
Detection point
(997.5 msec)
14ms VH pulse
10
100
1000
0
200
400
600
800
1000
Temp (˚C)
Time (msec)
14ms VH pulse
Detection point
(997.5 msec.)
All sensor characteristics shown in this bro-
chure represent typical characteristics. Actual
characteristics vary from sensor to sensor and
from production lot to production lot. The only
characteristics warranted are those shown in
the Specification on Page 3.
2. Operation Principle
The optimum conditions of sensitivity and selectivity
The optimum conditions of sensitivity and selectivity
to CO of the TGS2442 occurs at sensor temperatures
less than 100˚C. However, at these lower temp-
eratures, the sensing element may be influenced by
humidity and other contaminants, so the sensing
element requires periodic heat cleaning at more
than 300˚C. As a result, the TGS2442 is pulse heated
to achieve optimal sensing characteristics at low
temperatures.
Figure 6a shows the pattern of resistance change
ratio (Rs/Ro) for various CO concentrations which
occurs during the 1 second heater pulse cycle, starting
with application of the 14ms V
H
pulse. During the
V
H
pulse, initially sensor resistance drops quickly
and then returns to a higher value. After the V
H
pulse concludes and the sensing element’s surface
temperature begins to decrease (Fig. 6b), sensor
resistance reaches to its maximum value and then
begins to decline. Note that the shape of the response
pattern varies according to the concentration of
CO--higher CO concentrations result in a minimum
Rs/Ro value which occurs more quickly and has a
lower value. In addition, shortly after the V
H
pulse,
the Rs/Ro value also trends downwards at a greater
rate for higher CO concentrations after reaching its
maximum value.
A signal detection point of 997.5ms into the V
H
pulse
cycle (ref. timing chart in Fig. 3) is used to obtain the
optimum combination of gas sensitivity performance
and minimized ambient humidity effect.
Figure 5 - Relationship of sensor temperature and
V
H
pulse width (V
H
=4.8V, R
H
=17Ω)
Figure 6a - Sensitivity characteristics during the V
H
pulse cycle
(Ro = Rs in 100ppm CO at 997.5ms of V
H
cycle)