
35
3851 Group
(Built-in 16 KB ROM)
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
RESET CIRCUIT
To reset the microcomputer, RESET pin must be held at an “L”
level for 20 cycles or more of XIN. Then the RESET pin is returned
to an “H” level (the power source voltage must be between 2.7 V
and 5.5 V, and the oscillation must be stable), reset is released.
After the reset is completed, the program starts from the address
contained in address FFFD16 (high-order byte) and address
FFFC16 (low-order byte). Make sure that the reset input voltage is
less than 0.54 V for VCC of 2.7 V.
Fig. 42 Reset sequence
Fig. 41 Reset circuit example
(Note)
0.2V
CC
0V
0V
Poweron
V
CC
RESET
V
CC
RESET
Power source
voltage detection
circuit
Power source
voltage
Reset input
voltage
Note : Reset release voltage ; Vcc=2.7 V
RESET
D
a
t
a
φ
A
d
d
r
e
s
s
S
Y
N
C
X
I
N
:
1
0
.
5
t
o
1
8
.
5
c
l
o
c
k
c
y
c
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s
X
I
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?
?
??
?
FFFC F
F
F
D
AD
H
,
L
?
??
?
?
AD
L
A
D
H
1
:
T
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q
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l
a
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f
f
(
X
I
N
)
a
n
d
f
(φ)
i
s
f
(
X
I
N
)
=
8
•
f
(φ)
.
2
:
T
h
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q
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a
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(
?
)
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.
3
:
A
l
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a
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x
c
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a
b
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.
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R
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T
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