FUJITSU MB3773 - Manual (Page 13)

MB3773
13
■ ■ ■ ■ APPLICATION CIRCUIT
EXAMPLE 1: Monitoring 5V Supply Voltage and Watchdog Timer
VCC (5V)
MB3773
RESET
RESET
CK
GND
Logic circuit
Notes :
•
Supply voltage is monitored using V
S
.
•
Detection voltage are V
SH
and V
SL
.
C
T
1
2
3
4
8
7
6
5
EXAMPLE 2: 5V Supply Voltage Monitoring (external fine-tuning type)
V
CC
(5V)
1
2
3
4
8
7
6
5
MB3773
RESET
RESET
CK
GND
Logic circuit
Notes :
•
Vs detection voltage can be adjusted externally.
•
Based on selecting R
1
and R
2
values that are sufficiently lower than the resistance of the IC’s
internal voltage divider, the detection voltage can be set according to the resistance ratio of
R
1
and R
2
(See the table below.)
R
1
R
2
C
T
R
1
(k
Ω Ω Ω Ω
) R
2
(k
Ω Ω Ω Ω
) Detection voltage: V
SL
(V) Detection voltage: V
SH
(V)
10 3.9 4.4 4.5
9.1 3.9 4.1 4.2