Datasheet

Revised 08/12
2
TECHNICAL INFORMATION FOR TGS3870
Sensing
Element
Heater coil
Lead wire
Charcoal filter
Stainless steel gauze
Lead pin
Overhead view
of sensor base
Base
VH .9V
.2V
Vc 5V
0V
(Microprocessor
ports)
RL-CH4 H
L
RL-CO H
L
VRL CH4-IN
CO-IN
5 sec.
15 sec.
10 ms
(Operating
conditions)
0V
5 sec.
15 sec.
(1 cycle = 20 sec.)
5 ms
10 ms
5 ms
10 ms
5 ms
10 ms
5 ms
10 ms
5 ms
1. Specications
1-1 Features
* Miniature size and low power consumption
* High sensitivity and selectivity to both methane
and carbon monoxide (CO)
* Low sensitivity to alcohol vapor
* Long life and low cost
1-2 Applications
* Combination methane and CO detectors
1-3 Structure
Figure 1 shows the structure of TGS3870. A heater
coil and an electrode are embedded in a small bead
of SnO2 sensing material. The heater is connected
to pin Nos. 1 and 3 while the electrode is connected
to pin No. 2. Both the heater and the electrode are
composed of Pt wire and are spot welded to sensor
pins (made of Ni-Fe 42% alloy).
The sensor base is made of PBT (poly butylene
terephthalate), and the sensor cap is made of
Figure 1 - Sensor structure
Figure 2 - Timing chart
nickel-plated steel. The upper opening in the cap is
covered with a double layer of 100-mesh stainless
steel gauze (SUS316) and the sensor cap also has an
activated charcoal lter for reducing the inuence of
interference gases.