MB3771PF データシートの表示（PDF） - Fujitsu

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MB3771PF

BIPOLAR Power Supply Monitor

Fujitsu 

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

11

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