FIC98648 Datasheet, PDF (3/14 Pages) List of Unclassifed Manufacturers – Microprocessor for use with TGS4160 in automatic CO2 monitors

TECHNICAL INFORMATION FOR FIC98648
1-3 Two output signals
FIC98648 generates two separate output signals:
a) For calculating CO2 concentrations, a pulse width
modulated (PWM) signal is output.
b) An On/Off signal is generated as a control signal
for devices such as ventilation fans, dampers, etc.
4-1 Pins for the initial setting of operational conditions
To optimize sensor performance, the following pins
are provided for setting operational conditions at the
time of power-on. No change can be made to
operational conditions after the initial setting without
powering off and then repowering the device.
Notes:
1) The microprocessor is designed to assume the
highest value of EMF reading is representative of
400ppm of CO2 (ambient air levels). As a result, an
accurate reading cannot be expected if the sensor is
used in an environment where CO2 constantly exists
at higher concentrations than can be found in a
normal clean environment.
2) This device is not suitable for usage in life saving
equipment.
4-1-1 Input signal for setting the sensor’s initial warm-
up time (Pin No. 10)
Initial warm-up time, which is necessary to stabilize
the sensor’s output signal after an unpowered period,
is set by input of a signal to port R43 (see Table 2).
No signal can be taken from the microprocessor’s
output ports during initial warm-up time.
Setting
Signal Input
"H"
"L"
2. Basic Functions
2-1 Initial setting of operational conditions
In order to achieve optimal performance of the sensor,
manual preset of operational conditions is provided.
2-2 Automatic operation
Once power is supplied, an initial warm-up timer is
activated. When the initial warm-up time is finished,
the microprocessor will automatically begin
operation and commence generating the two output
signals mentioned above.
2-3 Line test
The microprocessor has the ability to perform a line
test for checking the functionality of the
microprocessor and the surrounding circuits. This
allows users to eliminate tool testing which is
normally done on the production line after assembly.
Initial warm-up
time (T1)
30 minutes
120 minutes
Table 2 - Initial warm-up time setting (AM-4 default = "L")
4-1-2 Input signals VL and TK for benchmark adjustment
(Pins No. 11 and 12)
The benchmark level is normally set at the lowest
value of the sensor’s signal (Vg), which is considered
as 400ppm of CO2 (ambient levels). The benchmark
level Vg is renewed whenever a lower signal voltage
than the present benchmark level is read from the
sensor (as described in Sec. 1-Automatic calibration).
If the benchmark level Vg is not renewed for a pre-
set period of time (TK), it is automatically adjusted
upward by a pre-set voltage (VL) which corresponds
to an equivalent concentration of CO2. Table 3 shows
the user-determined settings for VL and TK which
can be selected by applying a signal to Ports R50 and
R51 respectively.
3. Pin Arrangement
Pin arrangement of FIC98648 is shown in Figure 1.
4. Pin Functions
The basic pin functions of FIC98648 are shown in
Table 1 (shown on Page 4).
Setting
Benchmark
adjustment level
(VL)
Benchmark
adjustment time
(TK)
Terminal
Symbol Pin No.
Signal input
"H"
"L"
R50
11
5ppm
20ppm
equivalent equivalent
R51
12
1 day
7 days
Table 3 - Benchmark adjustment level and timer setting
(AM-4 default = 20ppm equiv. and 1 day)
Revised 08/03
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