
Revised 06/04
9
TECHNICAL INFORMATION FOR FIC03272
Analog output (0~3V)
for CO
2
concentration
R91
FIC03272
1M
10k
10
μ
LM324N
6.2V
100
1M
22k
1
2
3
25
5-3
System reset circuit
Under normal operating conditions, an “H” signal is
continuously applied to the RESET port (Pin #3).
When an “L” signal is applied to the RESET port for
a period of one machine cycle or longer, the internal
logic circuit of FIC03272 and the micro-processor’s
program return to the same condition which exists
just after powering on the unit, effectively resetting
the system.
To perform the above described system reset function
automatically, a circuit such as that shown in Figure
6 is suggested. This kind of automatic system reset
circuit is useful in circumstances such as just after
powering on, after a momentary power interruption,
at the moment of recovery after a sudden drop of
voltage, etc. The microprocessor’s program some-
times does not run correctly in these cases due to a
malfunction of the internal logic circuit in the
processor. Manual resets help to assure normal
operation of the microprocessor’s program.
5-4
CO
2
concentration signal circuit
Port 91 (Pin No. 25) outputs a PWM signal which
represents a CO
2
concentration in the range between
400 and 3000ppm. Figure 7 illustrates a sample circuit
for converting a PWM signal to a linear output of 0~3V
DC. A delay of several seconds is anticipated in the
DC voltage concentration signal because a C-R
combination is used in the circuit. A 100
resistor is
connected in series to protect the external circuit from
excessive current.
5-5
Circuit for damper control signal
Figure 8 shows an example circuit in which an H/L
signal which is output from port R60 (Pin No. 16)
and converted to an On/Off signal for controlling
the opening/closing of a damper. A 100
resistor is
connected in series to protect the external circuit from
excessive current.
Figure 6 - Reset circuit
Figure 7 - CO
2
concentration signal circuit
1k
3.9k
4. 7k
103
2SA1015Y
104
14
28
3
+4.4V
FIC03272
V
DD
V
SS
RESET
16
10k
6. 2V
100
2SA1015Y
1k
10k
FIC03272
Damper control signal
R60
Figure 8 - Damper control circuit