Datasheet
Revised 10/12
2
TECHNICAL INFORMATION FOR TGS2620
1. Basic Information and Specications
1-1 Features
* High selectivity to volatile organic vapors
* Low power consumption
* Small size
* Long life
1-2 Applications
* Alcohol testers
* Organic vapor detectors/alarms
* Solvent detectors for factories, dry cleaners, and
semiconductor industries
1-3 Structure
Figure 1 shows the structure of TGS2620. Using thick
lm techniques, the sensor material is printed on
electrodes (noble metal) which have been printed onto
an alumina substrate. One electrode is connected to
pin No.2 and the other is connected to pin No.3. The
sensor element is heated by RuO2 material printed
onto the reverse side of the substrate and connected
to pins No.1 and No.4.
Lead wires are Pt-W alloy and are connected to sensor
pins which are made of Ni-plated Ni-Fe 50%.
The sensor base is made of Ni-plated steel. The sensor
cap is made of stainless steel. The upper opening in
the cap is covered with a double layer of 100 mesh
stainless steel gauze (SUS316).
1-4 Basic measuring circuit
Figure 2 shows the basic measuring circuit. Circuit
voltage (Vc) is applied across the sensor element
which has a resistance (Rs) between the sensor’s two
electrodes and the load resistor (RL) connected in
series. When DC is used for Vc, the polarity shown in
Figure 2 must be maintained. The Vc may be applied
intermittently. The sensor signal (VRL) is measured
indirectly as a change in voltage across the RL. The
Rs is obtained from the formula shown at the right.
Vc - VRL
VRL
Rs = x RL
Formula to determine Rs
Fig. 1 - Sensor structure
Fig. 2 - Basic measuring circuit
NOTE: In the case of VH, there is no polarity, so pins 1 and 4 can
be considered interchangable. However, in the case of VC, when
used with DC power, pins 2 and 3 must be used as shown in the
Figure above.
Electrodes
Heater
Sensing material
Lead wire
1.5mm
Substrate
1.5mm
(Reverse side)
Lead wire
Stainless steel gauze
Lead pin
Metal cap
Sensor element