MB3773 Datasheet, PDF (16/29 Pages) Fujitsu Component Limited. – Power Supply Monitor with Watch-Dog Timer

MB3773
EXAMPLE 5: Monitoring Two Supply Voltages (with hysteresis and reset output)
VCC2 (12 V)
VCC1 (5 V)
CT
MB3773
1
8
2
7
3
6
4
5
1.2 kΩ
R1
20 kΩ
R6
30 kΩ
R3
Diode
180 kΩ
R4
+
_
Comp. 1
+
_
Comp. 2
5.1 kΩ
R2
4.7 kΩ
R5
Logic circuit
RESET
RESET
CK
GND
Example : Comp. 1, Comp. 2
: MB4204, MB47393
Notes : • When either 5 V or 12 V supply voltage decreases below its detection voltage (VSL),
the MB3773 RESET terminal is set to High and the MB3773 RESET terminal is set to Low.
• Use VCC1 ( = 5 V) to power the comparators (Comp. 1 and Comp. 2) in the external circuit shown
above.
• The detection voltage of the VCC2 ( = 12 V) supply voltage is approximately 9.2 V/9.4 V and has a
hysteresis width of approximately 0.2 V. For the formulas for finding hysteresis width and detection
voltage, refer to section 4.
16