M38197MA Datasheet, PDF (45/60 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

RESET CIRCUIT
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 2.8 V and 5.5
V, and XIN oscillation is stable), reset is released. In order to give
the XIN clock time to stabilize, internal operation does not begin
until after about 4000 XIN clock cycles (256 cycles of f(XIN)/16) are
completed. After the reset is completed, the program starts from
the address contained in address FFFD16 (high-order) and ad-
dress FFFC16 (low-order). Make sure that the reset input voltage
is 0.5 V or less for 2.8 V of VCC.
MITSUBISHI MICROCOMPUTERS
3819 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
RESET
Poweron
Power source
voltage
VCC _{0 V}
(Note)
Reset input
voltage
0V
0.2VCC
Note : Reset release voltage : VCC = 2.8 V
RESET
VCC
Power source voltage
detection circuit
Fig. VB-2 Example of reset circuit
XIN
φ
RESET
Internal reset
Address
Data
SYNC
?
?
?
?
FFFC
FFFD ADH, ADL
?
?
?
?
ADL
ADH
Reset address from
vector table
about 4000
Notes 1 : f(XIN) and f(φ) are in the relationship : f(XIN) = 8•f(φ)
XIN clock cycles
2 : A question mark (?) indicates an undefined state that depends on the previous state.
Fig. VB-2 Reset sequence
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