6-2. Reset Circuit
The reset circuit initializes the microcomputer prog ram when Power is ÒONÓ from ÒOFFÓ.
Low voltage at pin
48
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
48
of microcomputer is set to Hi .
Reset voltage will be hold ÒHiÓ until the 12V line voltage drops to 9.90V even though the power shuts
down.
Fig. 6-7
Fig. 6-8
−
MAIN P.W.B.
Microcomputer
RESET OUT.
RESET
56
48
C204
0V
R252
1
0V
8
2
3
IC5(1/2)
+
5V
D208
R287
C215
R284
R286
C225
R285
C226
R292
R289
R288
0V 0V 0V 0V
12V
12V line
12V line
5V line
5V line
Reset volage
Reset volage
Time
Time
10.9V
9.9V
12
6
0
12
6
0
Power is ON
Voltage (V)
Power is OFF
Voltage (V)
– 59 –
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