MB3773 Datasheet, PDF (18/31 Pages) Fujitsu Component Limited. – Power Supply Monitor with Watch-Dog Timer

MB3773
EXAMPLE 6: Monitoring Low voltage and Overvoltage Monitoring (with hysteresis)
V_CC (5
MB3773
1
8
2
7
C_T
3
6
4
5
20 kΩ
R₆
30 kΩ
R₃
Diode
Logic circuit
RESET
RESET
CK
GND
1.2 kΩ
R₁
180 kΩ
R₄
+
_
Comp. 1
_
+
Comp. 2
5.6 kΩ
R₆
4.7 kΩ
R₅
Example : Comp. 1, Comp. 2
: MB4204, MB47393
RESET
0
V_1L V_1H
V_2L V_2H
V_CC
Notes :
• Comp. 1 and Comp. 2 are used to monitor for overvoltage while the MB3773 is used to monitor for low voltage.
Detection voltages V_1L/V_1H at the time of low voltage are approximately 4.2 V/4.3 V. Detection voltages V_2L/V_2H at
the time of overvoltage are approximately 6.0 V/6.1 V.For the formulas for finding hysteresis width and detection
voltage, see EXAMPLE 4.
• Use V_CC ( = 5 V) to power the comparators (Comp. 1 and Comp. 2) in the external circuit shown above.
Document Number: 002-08513 Rev. *A
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