Datasheet

Revised 08/12
5
TECHNICAL INFORMATION FOR TGS3870
0.1
1
10
-20 -10 0 10 20 30 40 50 60
Methane 1000ppm
Methane 3000ppm
Methane 9000ppm
Rs/Ro
Temperature (˚C)
65% RH
good. In comparison to CO, sensitivity to hydrogen
is very low as indicated by the extremely high
concentrations of hydrogen required to approximate
very low CO levels. Cross-sensitivity to methane is
very low according to its high resistance values.
2-2 Temperature dependency
Figures 6a and 6b show the temperature dependency
of TGS3870. The Y-axis shows the ratio of sensor
resistance for gas concentrations under various
atmospheric conditions (Rs) to the sensor resistance
at 20˚C and 65%RH (Ro) for 3000ppm of methane
(Fig. 6a) and for 100ppm of CO (Fig. 6b).
An inexpensive way to compensate for temperature
dependency would be to incorporate a thermistor in
the detection circuit. Separate compensation circuits
should be prepared for CO and methane sensing.
Figure 6a - Temperature dependency for methane sensing
(Ro = Rs in 3000ppm of CH4 at 20˚C/65%RH, VH =0.9)
Figure 6b - Temperature dependency for CO sensing
(Ro = Rs in 100ppm of CO at 20˚C/65%RH, VH =0.2)
0.01
0.1
1
10
100
1000
10000
-20 -10 0 10 20 30 40 50 60
CO 30ppm
CO 100ppm
CO 300ppm
CO 900ppm
Rs/Ro
Temperature (˚C)
65% RH
Rs/Ro Rs/Ro