MC34161, MC33161

http://onsemi.com

8

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:

Figure 17. Dual Negative Overvoltage Detector

V

R

1

R

2

(V

V

R

1

R

2

(V

R

1

R

2

+

V

V

R

1

R

2

+

V

V

+

1.27V

+

1.27V

+

2.8V

+

0.6V

+

–

2.54V

Reference

–

+

–

+

+

–

4

1

7

2

3

5

6

R1

–VS1

R1

–VS2

R2

R2

8

VCC

Input –VS

Output

Voltage

Pins 5, 6

Gnd

V1

V2

VCC

LED ‘ON’

VHys

Gnd

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:

Figure 18. Dual Negative Undervoltage Detector

V

R

1

R

2

(V

V

R

1

R

2

(V

R

1

R

2

+

V

V

R

1

R

2

+

V

V

+

1.27V

+

1.27V

+

2.8V

+

0.6V

+

–

8

–

+

–

+

+

–

4

1

7

2

3

5

6

R1

–VS1

R1

–VS2

2.54V

Reference

R2

R2

VCC

VHys

Input –VS

Output

Voltage

Pins 5, 6

Gnd

V1

V2

VCC

LED ‘ON’

Gnd