7641_06 Datasheet, PDF (265/385 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

7641 Group
APPLICATION
2.11 Reset
2.11 Reset
2.11.1 Connection example of reset IC
Figure 2.11.1 shows the system example which switches to the RAM backup mode by detecting a drop of
the system power source voltage with the INT interrupt.
System power
source voltage
+5 V
+
VC C1
RESET
VC C2
INT
V1 _GND Cd
VC C
RESET
INT
VSS
7641 Group
M62009L, M62009P, M62009FP
Fig. 2.11.1 RAM backup system
2.11.2 Notes on reset
(1) Connecting capacitor
In case where the RESET signal rise time is long, connect a ceramic capacitor or others across the
RESET pin and the VSS pin. Use a 1000 pF or more capacitor for high frequency use. When
connecting the capacitor, note the following :
• Make the length of the wiring which is connected to a capacitor as short as possible.
• Be sure to verify the operation of application products on the user side.
q Reason
If the several nanosecond or several ten nanosecond impulse noise enters the RESET pin, it may
cause a microcomputer failure.
Rev.2.00 Aug 28, 2006 page 134 of 148
REJ09B0336-0200