MITSUBISHI MICROCOMPUTERS
3827 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
RESET CIRCUIT
Poweron
To reset the microcomputer, RESET pin should be held at an “L”
level for 2 µs or more. Then the RESET pin is returned to an “H”
level (the power source voltage should be between VCC(min.) and
5.5 V, and the oscillation should be stable), reset is released. After
the reset is completed, the program starts from the address con-
tained in address FFFD16 (high-order byte) and address FFFC16
(low-order byte). Make sure that the reset input voltage is less
than 0.2 VCC for VCC of VCC (min.).
(Note)
Power source
voltage
RESET
VCC
0V
Reset input
voltage
0V
0.2VCC
Note : Reset release voltage ; VCC=VCC(min.)
RESET
VCC
Power source
voltage detection
circuit
Fig. 48 Reset Circuit Example
XIN
φ
RESET
Internal
reset
Reset address from
vector table
Address
Data
?
?
?
?
FFFC
FFFD
ADH, ADL
ADL
ADH
SYNC
XIN : about 8200 cycles
Notes 1: The frequency relation of f(XIN) and f(φ) is f(XIN) = 8 • f(φ).
2: The question marks (?) indicate an undefined state that
depends on the previous state.
Fig. 49 Reset Sequence
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MITSUBISHI [ Mitsubishi Group ]
