MB3771_06 Datasheet, PDF (12/21 Pages) Fujitsu Component Limited. – Power Supply Monitor

MB3771
(2) 5 V Reference Voltage Generation and 5V Monitoring (No.1)
Detection Voltage = 4.2 V
In the above examples, the output voltage and the detection voltage are determined by the following equations:
Output Voltage = (R3 + R4) × VSC/R4
15 V
CT
0.47 µF
R5 : 3 kΩ
MB3771
1
8
2
7
3
6
4
5
RESET
5 V(≅ 50 mA)
R3 : 3.6 kΩ
R4 : 1.2 kΩ
(3) 5 V Reference Voltage Generation and 5 V Monitoring (No. 2)
The value of R1 should be calculated from the current consumption of the MB3771, the current flowing at R2 and
R3, and the 5 V output current. The table below provides sample resistance values for reference.
VCC (V)
R1 (kΩ)
Output Current (mA)
40
11
< 1.6
24
6.2
< 1.4
15
4.7
< 0.6
VCC
CT
GND
1
2
3
4
R2 :
100 kΩ
R3 : 33 kΩ
R1
8
7
6
5
0.47 µF
RESET
5V
(4) 1.245 V Reference Voltage Generation and 5 V Monitoring
Resistor R1 determines Reference current. Using 1.2 kΩ as R1, reference current is about 2 mA.
VCC
(5 V)
CT
0.47 µF
GND
R1 : 10 kΩ
1
8
2
7
3
6
4
5
RESET
Reference Voltage
1.245 V Typ
12