UT01VS33D Datasheet, PDF (10/15 Pages) Aeroflex Circuit Technology – UT01VS33D Voltage Supervisor

VDD 3.3V
R1
VTH_OV= (R1+R2)/R2 ) * VPFI
VPFI=0.6V +/‐ 25mV
R2
1 MR
WDO 8
2 VDD RESET_OD 7
3 GND
4 PFI
WDI 6
PFO 5
UT01VS33D
UNDER VOLTAGE
MONITOR
RPU1
RPU2
VDD
IN1 uP
RESETB
I/O
3.3V INV
GATE
R3
VTH_OV= (R3+R4)/R4 ) * VPFI
VPFI=0.6V +/‐ 25mV
R4
1 MR
WDO 8
2 VDD RESET_OD 7
3 GND
4 PFI
WDI 6
PFO 5
UT01VS33D
OVER VOLTAGE
MONITOR
RESETB
I/O
Figure 8. UT01VS33D Under Voltage and Over Voltage Power Supply Monitoring and Reset
Shown in Figure 8 is an application using two UT01VS33D Voltage Supervisors to monitor both under voltage and over voltage of
a power supply. In this application the top Voltage Supervisor monitors the under-voltage of a 3.3V power supply while the bottom
Voltage Supervisor monitors the over voltage of the same 3.3V power supply.
The 3.3Vsupply is monitored through the PFI input of both Voltage Supervisors. Resistor values for both under voltage and over
voltage monitoring can be set to accommodate a range of power supply voltages.
During normal operation where VDD is within the allowed range (VDD_UND < VDD < VDD_OV), RESET_OD of both Voltage
Supervisors will be at logic high level. The Table 1 below shows the truth table for functional, under voltage detection and over
voltage detection.
10