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S1220PBID Datasheet, PDF (10/18 Pages) ON Semiconductor – Universal Voltage Monitors
◁
MC34161, MC33161, NCV33161
Input VS
CH2 V4
V3
CH1
V2
V1
VHys2
VHys1
Output
Voltage
Pins 5, 6
GND
VCC
`ON'
GND
LED `OFF'
LED `ON' `OFF' LED `ON'
VCC
8
VS 1
2.54V
Reference
-
R3
7
++
+
2.8V
2+ -
6
R2
1.27V
-
++
+
0.6V
R1
3+ -
1.27V
5
4
The above figure shows the MC34161 configured as a positive voltage window detector. This is accomplished by connecting channel 1 as an undervoltage detector,
and channel 2 as an overvoltage detector. When the input voltage VS falls out of the window established by V1 and V4, the LED will turn ‘ON’. As the input voltage
falls within the window, VS increasing from ground and exceeding V2, or VS decreasing from the peak towards ground and falling below V3, the LED will turn ‘OFF’.
With the dashed line output connection, the LED will turn ‘ON’ when the input voltage VS is within the window.
For known resistor values, the voltage trip points are:
ǒ Ǔ ǒ Ǔ V1 + (Vth1 * VH1)
R1
R3
)
R2
)
1
V3 + (Vth2 * VH2)
R2
)
R1
R3
)
1
For a specific trip voltage, the required resistor ratio is:
R2
R1
+
V3(Vth2
V1(Vth1
*
*
VH2)
VH1)
*
1
R3
R1
+
V3(V1 * Vth1
V1(Vth2 *
) VH1)
VH2)
ǒ Ǔ V2 + Vth1
R1
R3
)
R2
)
1
ǒ Ǔ V4 + Vth2
R2
)
R1
R3
)
1
R2
R1
+
V4
V2
x
x
Vth1
Vth2
*
1
R3
R1
+
V4(V2 * Vth1)
V2 x Vth2
Figure 20. Positive Voltage Window Detector
VCC
8
2.54V
GND
1
Reference
CH2 V1
Input -VS
V2
CH1 V3
V4
VHys2
VHys1
-
R3
7
++
+
2.8V
2+ -
6
R2
1.27V
-
++
Output
Voltage
Pins 5, 6
VCC
`ON'
GND
LED `OFF'
LED `ON' `OFF' LED `ON'
+
0.6V
R1
3+ -
1.27V
5
-VS
4
The above figure shows the MC34161 configured as a negative voltage window detector. When the input voltage −VS falls out of the window established by V1
and V4, the LED will turn ‘ON’. As the input voltage falls within the window, −VS increasing from ground and exceeding V2, or −VS decreasing from the peak towards
ground and falling below V3, the LED will turn ‘OFF’. With the dashed line output connection, the LED will turn ‘ON’ when the input voltage −VS is within the window.
For known resistor values, the voltage trip points are:
For a specific trip voltage, the required resistor ratio is:
V1
+
R1(Vth2 * Vref)
R2 ) R3
)
Vth2
V2
+
R1(Vth2 * VH2 *
R2 ) R3
Vref)
)
Vth2
*
VH2
V3
+
(R1
)
R2)(Vth1
R3
*
Vref)
)
Vth1
V4
+
(R1
)
R2)(Vth1 *
R3
VH1
*
Vref)
)
Vth1
*
VH1
R2
R1
)
R3
+
V1 * Vth2
Vth2 * Vref
R2
R1
)
R3
+
V2 * Vth2 ) VH2
Vth2 * VH2 * Vref
R1
R3
)
R2
+
Vth1 * Vref
V3 * Vth1
R1
R3
)
R2
+
Vth1 * VH1 * Vref
V4 ) VH1 * Vth1
Figure 21. Negative Voltage Window Detector
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