– 115 –
6-2. Reset Circuit
The reset circuit initializes the microcomputer program when Power is “ON” from “OFF”
Low voltage at pin
resets the microcomputer, and HI activates the microcomputer
Fig. 6-7 shows the reset circuit and Fig. 6-8 shows waveform at each point when power is turned on and
off.
When power is turned on, 12V line and 5V line voltages rise and 12V line voltage reaches 10.9V an
reset voltage input to pin
of microcomputer is set to Hi.
Reset voltage will be hold “Hi” until the 12V line voltage drops to 9.90V even though the power shuts
down.
Fig. 6-7
Fig. 6-8
48
48
12V line
Power is ON
Voltage (V)
Power is OFF
Voltage (V)
5V line
10.9V
Time
Time
9.9V
Reset voltage
Reset voltage
12V line
5V line
12
6
0
12
6
0
0V
RESET
12V
MAIN P.W.B.
R252
R284
R288
IC5(1/2)
R292
R286
R289
R285
C204
C226
C225
C215
0V
0V
0V
0V
5V
D208
R287
0V
48
RESET OUT.
56
2
8
1
3
Microcomputer
+
-