MB3771 데이터 시트보기 (PDF) - Fujitsu

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MB3771

BIPOLAR Power Supply Monitor

Fujitsu 

MB3771

4. 5 V and 12 V Power Supply Monitor (2 types of power supply monitor VCC1 = 5 V, VCC2 =12 V)

• 5 V is monitored by VSA. Detection voltage is about 4.2 V

• 12 V is monitored by VSB. When R1 = 390 kΩ and R2 = 62 kΩ, Detection voltage is about 9.0 V.Generally the

detection voltage is determined by the following equation.

Detection Voltage = (R1 + R2) × VSB/R2

VCC2

VCC1

CT

MB3771

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R1: 390 kΩ

R2: 62 kΩ

RESET

Logic

circuit

5. 5 V and 12 V Power Supply Monitor (RESET signal is generated by 5 V, VCC1 = 5 V, VCC2 = 12 V)

• 5 V is monitored by VSA, and generates RESET signal when VSA detects voltage sagging.

• 12 V is monitored by VSC, and generates its detection signal at OUTC.

• The detection voltage of 12 V monitoring and its hysteresis is determined by the following equations.

Detection voltage =

R1 + R2 + R3

R2 + R3

× VSC

(8.95 V in the circuit above)

R1 (R3 − R3 // R4)

Hysteresis width =

× VSC

(R2 + R3) (R2 + R3 // R4)

(200 mV in the circuit above)

VCC2

VCC1

R L: 10 kΩ

R1: 390 kΩ

R5: 100 kΩ

R2: 33 kΩ

R4: 510 kΩ

CT

R3: 30 kΩ

MB3771

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RESET

IRQ or

Port Logic Circuit

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