MB3773
EXAMPLE 6 : Montitoring Low voltage and Overvoltage Monitoring (with hysterisis)
VCC (5V)
20k
R6
MB3773
Logic circuit
1
2
3
4
8
7
6
5
RESET
RESET
CK
Diode
CT
30k
R3
GND
180k
R4
_
+
_
+
Comp. 1
1.2k
R1
Comp. 2
5.6k
R2
4.7k
R5
Example
: Comp. 1, Comp. 2
: MB4204, MB47393
RESET
VCC
0
V2L V2H
V1L V1H
• Comp. 1 and Comp. 2 are used to monitor for overvoltage while the MB3773 is used to monitor for low
voltage.
Detection voltages V1/V1H at the time of low voltage areappoximately 4.2V/4.3V. Detection voltages
V2L/V2H at the time of overvoltage are approximately 6.0V/6.1V.
For the formulas for finding hysterisis width and detection voltage, see section 4.
• Use VCC (=5V) to power the comparators (Comp. 1 and Comp. 2) in the external circuit shown above.
14
FUJITSU [ FUJITSU ]
