
Rev.2.10
2005.11.14
page 36 of 86
REJ03B0093-0210
3850 Group (Spec.A)
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. 40 Reset sequence
Fig. 39 Reset circuit example
(Note)
0.2VCC
0V
Poweron
VCC
RESET
VCC
RESET
Power source
voltage detection
circuit
Power source
voltage
Reset input
voltage
Note : Reset release voltage; Vcc = 2.7 V
RESET
Data
φ
Address
SYNC
XIN: 8 to 13 clock cycles
XIN
?
FFFCFFFD
ADH,L
?
ADL
ADH
1: The frequency relation of f(XIN) and f(
φ) is f(XIN) = 2 f(φ).
2: The question marks (?) indicate an undefined state that depends on the previous state.
3: All signals except XIN and RESET are internals.
Reset address from the vector table.
Notes
RESETOUT