MB3771 Datasheet: Bipolar Power Supply Monitor - Fujitsu

MB37714. 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 thedetection voltage is determined by the following equation.Detection Voltage = (R1 + R2) × VSB/R2VCC2VCC1MB3771CT12348765R1: 390 kΩR2: 62 kΩRESETLogiccircuit5. 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 hysterisis is determined by the following equations.Detection voltage =R1 + R2 + R3R2 + R3× VSC (8.95 V in the circuit above)Hysterisis width =R1 (R3 − R3 // R4)(R2 + R3) (R2 + R3 // R4)× VSC (200 mV in the circuit above)VCC2VCC1R L: 10 kΩR1: 390 kΩR2: 33 kΩR4: 510 kΩR5: 100 kΩCT1234MB37718765RESETIRQ orPort Logic CircuitR3: 30 kΩ9