3807_03 Datasheet, PDF (68/247 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

HARDWARE
FUNCTIONAL DESCRIPTION
Reset Circuit
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To reset the microcomputer, RESET pin should be held at an "L"
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level for 2 µs or more. Then the RESET pin is returned to an "H" level
(the power source voltage should be between 2.7 V and 5.5 V, and
the oscillation should 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.
RESET
Power source
VCC ^voltage
0V
Reset input
voltage
0V
Poweron
(Note)
0.2VCC
Note : Reset release voltage ; Vcc=2.7 V
RESET
VCC
Power source
voltage detection
circuit
Fig. 54. Reset circuit example
XIN
φ
RESET
Internal
reset
Address
Data
SYNC
?
?
?
?
FFFC FFFD ADH,L
Reset address from the vector table.
?
?
?
?
ADL
ADH
XIN: 10.5 to 18.5 clock 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. 55. Reset sequence
1-52
3807 GROUP USER’S MANUAL