MB3771PF-G-BND-JNE1 Datasheet, PDF (11/21 Pages) Fujitsu Component Limited. – ASSP For power supply applications BIPOLAR Power Supply Monitor

MB3771
9. Dual (Positive/Negative) Power Supply Voltage Monitoring (VCC = 5 V, VEE = Negative Power
Supply)
Monitors a 5 V and a negative (any given level) power supply. R1, R2, and R3 should be the same value.
Detection Voltage = VSB − VSB × R4/R3
Example if VEE = −5 V, R4 = 91 kΩ
Then the detected voltage = −4.37 V
In cases where VEE may be output when VCC is not output, it is necessary to use a Schottky barrier diode (SBD).
VCC
R5 : 5.1 kΩ
MB3771
R4
VEE
1
8
R3 :
2
7
20 kΩ
3
6
0.22 µF
CT
SBD
4
5
RESET
R1 : 20 kΩ
R2 : 20 kΩ
10. Reference Voltage Generation and Voltage Sagging Detection
(1) 9V Reference Voltage Generation and 5V/9V Monitoring
Detection Voltage = 7.2 V
In the above examples, the output voltage and the detection voltage are determined by the following equations:
Detection Voltage = (R1 + R2) × VSB/R2
15 V
V CC : 5 V
CT
0.47 µF
R 5 : 3 kΩ
MB3771
1
8
2
7
3
6
4
5
R3 :
7.5 kΩ
R4 :
1.2 kΩ
RESET
9 V (≅ 50 mA)
R 1: 300 kΩ
R 2: 62 kΩ
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