Alarm Delay Circuit; Application Circuit; Manufacturing Process; Handling And Storage Of Sensors - Figaro TGS2611 Application Notes

1-8 Alarm delay circuit

To prevent false alarms caused by transient
interference gases such as alcohol in cooking
vapors, a delay circuit modification such as that
shown in Figure 7 can be used. The alarm signal
generated by this circuit should be connected to
the comparator in the basic circuit (see Figure
1). The recommended timer period for alarm
delay is 15 seconds--the timer function should
be created by selecting the proper combination
of C and R .
4 15

1-9 Application circuit

An application circuit which incorporates all of
the advice included in Secs. 1-1 through 1-8 can
be seen in Appendix 1.
2. Manufacturing Process (see Fig. 8)

2-1 Handling and storage of sensors

Prior to usage, sensors should be stored at room
temperature in a sealed bag containing normal
clean air. During manufacturing, sensors should
be handled in a clean air environment and at
room temperature. Clean air refers to air free of
contaminants, excessive dust, solvent vapors,
etc. Room temperature should be 20~25˚C.
2-2 R selection
L
Choose the proper resistor for R
the ID number of the sensor and Table 1.

2-3 PCB assembly

Flux should be sufficiently dried before sensors
are assembled onto the PCB to avoid any
contamination of the sensor by flux vapors.

2-4 Sensor assembly

Manual soldering of the sensor to the PCB is
strongly advised. Solders composed of
Sn63:Pb37 or Sn60:Pb40 with non-chloric resin
flux (MIL: RMA Grade; for example, Almit KR-
19) are recommended for usage.
2-5 Final assembly
Avoid any shock or vibration which may be
caused by air driven tools. This may cause
breakage of the sensor's lead wires or other
physical damage to the sensor.
Revised 08/03
APPLICATION NOTES FOR TGS2611
V
C
Alarm signal
(Active = 'L')
by referring to
L
Investigation
15 sec. time delay circuit
R
8
D
6
R
15
R
12
R
14
Tr
+
C
4
R
13
Figure 7 - Alarm delay circuit
Acceptance of components
Acceptance of
classified sensor
PCB Assembly
RL selection
PCB Test
OK
Sensor and R Assembly
L
(manual soldering)
Final Assembly
(PCB, casing etc.)
Preheating
(≥48 hours)
NG
Gas Test
OK
Packing
Storage
Shipping
Figure 8 - Manufacturing process flowchart
R
9
Delayed alarm
signal
IC
3
(Active = 'L')
+
-
R
10
GND
Repair
*3
NG
Quality control sampling
*Alarm concentration
*Long term stability
5