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S1220PBID Datasheet, PDF (9/18 Pages) ON Semiconductor – Universal Voltage Monitors
◁
MC34161, MC33161, NCV33161
GND
V1
Input -VS
V2
Output VCC
Voltage
Pins 5, 6 GND
VHys
LED `ON'
VCC
8
2.54V
R2
1
Reference
-
R1
-VS1
7
+
2+ -
++
2.8V
6
R2
R1
1.27V
-
++
-VS2
+
0.6V
3+ -
5
1.27V
4
The above figure shows the MC34161 configured as a dual negative overvoltage detector. As the input voltage increases from ground, the LED will turn ‘ON’ when
−VS1 or −VS2 exceeds V2. With the dashed line output connection, the circuit becomes a dual negative undervoltage detector. As the input voltage decreases from
the peak towards ground, the LED will turn ‘ON’ when −VS1 or −VS2 falls below V1.
For known resistor values, the voltage trip points are:
For a specific trip voltage, the required resistor ratio is:
V1
+
R1
R2
(Vth
*
Vref)
)
Vth
V2
+
R1
R2
(Vth
*
VH
*
Vref)
)
Vth
*
VH
R1
R2
+
V1
Vth
*
*
Vth
Vref
R1
R2
+
V2
Vth
*
*
Vth
VH
) VH
* Vref
Figure 18. Dual Negative Overvoltage Detector
GND
V1
Input -VS
V2
Output VCC
Voltage
Pins 5, 6 GND
VHys
LED `ON'
VCC
8
2.54V
R2
1
Reference
-
R1
-VS1
7
+
2+ -
++
2.8V
6
R2
R1
1.27V
-
++
-VS2
+
0.6V
3+ -
5
1.27V
4
The above figure shows the MC34161 configured as a dual negative undervoltage detector. As the input voltage decreases towards ground, the LED will turn ‘ON’
when −VS1 or −VS2 falls below V1. With the dashed line output connection, the circuit becomes a dual negative overvoltage detector. As the input voltage increases
from ground, the LED will turn ‘ON’ when −VS1 or −VS2 exceeds V2.
For known resistor values, the voltage trip points are:
For a specific trip voltage, the required resistor ratio is:
V1
+
R1
R2
(Vth
*
Vref)
)
Vth
V2
+
R1
R2
(Vth
*
VH
*
Vref)
)
Vth
*
VH
R1
R2
+
V1
Vth
*
*
Vth
Vref
R1
R2
+
V2
Vth
*
*
Vth )
VH *
VH
Vref
Figure 19. Dual Negative Undervoltage Detector
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