Hitachi RAS-50FH5 - Page 80

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10. Reset Circuit
● The reset circuit initializes the microcomputer program when Power is ÒONÓ or ÒOFFÓ.
● Low voltage at pin
48
resets the microcomputer, and HI activates the microcomputer.
● Fig. 10-1 shows the reset circuit and Fig. 10-2 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 and
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.
Microcomputer
R252
R289
0V0V
R288
0V
5V
12V
HIC
R284
JW10
IC5 (1/2)
402C
48
RESET
Main
P. W. B
Fig. 10-1
512C
682R
522C
701C
622C 582R
0V
1
3
2
62
8
Ð
+
+
0V
0V
292R
12V line
12V line
5V line
5V line
Fig. 10-2
Reset voltage
Reset voltage
12
6
0
NO
sir
ew
oP
)V(
e
ga
t
l
o
V
12
6
0
F
F
Osir
ew
oP
)
V(
eg
atl
oV
Time
Time