S1220PBID Datasheet, PDF (8/18 Pages) ON Semiconductor – Universal Voltage Monitors

MC34161, MC33161, NCV33161
V₂
Input V_S
V₁
GND
Output V_CC
Voltage
Pins 5, 6 _GND
V_Hys
LED `ON'
V<sub>CC</sub>
8
2.54V
V<sub>S1</sub>
1
Reference
-
R<sub>2</sub> <sup>7</sup>
++
+
2.8V
V<sub>S2</sub>
R<sub>1</sub>
2+ <sub>-</sub>
1.27V
-
6
R<sub>2</sub>
++
+
0.6V
3+ <sub>-</sub>
5
R<sub>1</sub>
1.27V
4
The above figure shows the MC34161 configured as a dual positive overvoltage detector. As the input voltage increases from ground, the LED will turn ‘ON’ when
V<sub>S1</sub> or V<sub>S2</sub> exceeds V<sub>2</sub>. With the dashed line output connection, the circuit becomes a dual positive undervoltage detector. As the input voltage decreases from
the peak towards ground, the LED will turn ‘ON’ when V<sub>S1</sub> or V<sub>S2</sub> falls below V<sub>1</sub>.
For known resistor values, the voltage trip points are:
ǒ Ǔ V<sub>1</sub> + (V<sub>th</sub> * V<sub>H</sub>)
R<sub>2</sub>
R<sub>1</sub>
)
1
ǒ Ǔ V<sub>2</sub> + V<sub>th</sub>
R<sub>2</sub>
R<sub>1</sub>
)
1
For a specific trip voltage, the required resistor ratio is:
R<sub>2</sub>
R<sub>1</sub>
+
V<sub>th</sub>
V<sub>1</sub>
*
V<sub>H</sub>
*
1
R<sub>2</sub>
R<sub>1</sub>
+
V<sub>2</sub>
V<sub>th</sub>
*
1
Figure 16. Dual Positive Overvoltage Detector
V<sub>2</sub>
Input V<sub>S</sub>
V<sub>1</sub>
GND
Output V<sub>CC</sub>
Voltage
Pins 5, 6 <sub>GND</sub>
V<sub>Hys</sub>
LED `ON'
V_CC
8
2.54V
V_S1
1
Reference
-
7
R₂
+
V_S2
2+ _-
++
2.8V
6
R₁
1.27V
-
R₂
++
+
0.6V
3+ _-
5
R₁
1.27V
4
The above figure shows the MC34161 configured as a dual positive undervoltage detector. As the input voltage decreases towards ground, the LED will turn ‘ON’
when V_S1 or V_S2 falls below V₁. With the dashed line output connection, the circuit becomes a dual positive overvoltage detector. As the input voltage increases
from ground, the LED will turn ‘ON’ when V_S1 or V_S2 exceeds V₂.
For known resistor values, the voltage trip points are:
ǒ Ǔ V₁ + (V_th * V_H)
R₂
R₁
)
1
ǒ Ǔ V₂ + V_th
R₂
R₁
)
1
For a specific trip voltage, the required resistor ratio is:
R₂
R₁
+
V_th
V₁
*
V_H
*
1
R₂
R₁
+
V₂
V_th
*
1
Figure 17. Dual Positive Undervoltage Detector
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