M37517F8HP Datasheet, PDF (48/98 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

7517 Group
RESET CIRCUIT
To reset the microcomputer, RESET pin must be held at an “L”
level for 20 XIN cycles or more. Then the RESET pin is returned to
an “H” level (the power source voltage must be between 2.7 V and
3.6 V, and the oscillation must 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 0.54 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. 53 Reset circuit example
XIN
φ
RESET
RESETOUT
Address
Data
SYNC
?
?
?
?
FFFC FFFD ADH,L
Reset address from the vector table.
?
?
?
?
ADL
ADH
XIN: 8 to 13 clock cycles
Notes 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.
Fig. 54 Reset sequence
Rev.1.01 Aug 02, 2004 page 48 of 96