4501_M Datasheet, PDF (51/212 Pages) Renesas Technology Corp – 4-BIT CISC SINGLE-CHIP MICROCOMPUTER 4500 SERIES

4501 Group
HARDWARE
FUNCTION BLOCK OPERATIONS
(1) Power-on reset
Reset can be automatically performed at power on (power-on re-
set) by the built-in power-on reset circuit. When the built-in
power-on reset circuit is used, the time for the supply voltage to
rise from 0 V to 2.0 V must be set to 100 µs or less. If the rising
time exceeds 100 µs, connect a capacitor between the RESET pin
and VSS at the shortest distance, and input “L” level to RESET pin
until the value of supply voltage reaches the minimum operating
voltage.
(Note 1)
(Note 2)
RESET pin
(Note 1)
Pull-up transistor
100 µs or less
VDD (Note 3)
Power-on reset circuit output
Internal reset signal
Power-on reset circuit
Volgate drop detection circuit
Watchdog reset signal
Internal reset signal
WEF
Reset
state
Power-on Reset released
Notes 1:
This symbol represents a parasitic diode.
2: Applied potential to RESET pin must be VDD or less.
3: Keep the value of supply voltage to the minimum value
or more of the recommended operating conditions.
Fig. 35 Structure of reset pin and its peripherals, and power-on reset operation
Table 14 Port state at reset
Name
D0, D1
D2/C, D3/K
P00, P01, P02, P03
P10, P11, P12/CNTR, P13/INT
P20/AIN0, P21/AIN1
Notes 1: Output latch is set to “1.”
2: Pull-up transistor is turned OFF.
Function
D0, D1
D2, D3
P00–P03
P10–P13
P20, P21
State
High-impedance (Note 1)
High-impedance (Notes 1, 2)
High-impedance (Notes 1, 2)
High-impedance (Notes 1, 2)
High-impedance (Notes 1, 2)
Rev.2.01 Feb 07, 2005
REJ09B0192-0201
1-39