+

±

Micro-

Controller

+

3.3 V

Sensor

R1

10 0Ÿ

RPU

UV_OV

±

Open Drain Output Only!

VTH-

VTH+

VIN

Low when VIN < VTH-

Open Drain Output Only!

Output high

when VIN is

within window

R3

10 0Ÿ

R2

10 0Ÿ

Low when VIN > VTH+

Figure 6-7. Window Comparator

6.2.1.1 Design Requirements

For this design, follow these design requirements:

• Alert (logic low output) when an input signal is less than 1.1V

• Alert (logic low output) when an input signal is greater than 2.2V

• Alert signal is active low

• Operate from a 3.3V power supply

6.2.1.2 Detailed Design Procedure

Configure the circuit as shown in Figure 6-7. Connect VCC to a 3.3V power supply and VEE to ground. Make R1,

R2 and R3 each 10MΩ resistors. These three resistors are used to create the positive and negative thresholds

for the window comparator (VTH+ and VTH–).

With each resistor being equal, VTH+ is 2.2V and VTH- is 1.1V. Large resistor values such as 10MΩ are used to

minimize power consumption. The resistor values can be recalculated to provide the desired trip point values.

The sensor output voltage is applied to the inverting and noninverting inputs of the two comparators. Using two

open-drain output comparators allows the two comparator outputs to be Wire-OR'ed together.

The respective comparator outputs will be low when the sensor is less than 1.1V or greater than 2.2V. The

respective comparator outputs will be high when the sensor is in the range of 1.1V to 2.2V (within the "window"),

as shown in Figure 6-8.

6.2.1.3 Application Curve

VTH+ = 2.2 V

VTH± = 1.1 V

VIN

OUT

Figure 6-8. Window Comparator Results

For more information, see the Window comparator circuit application note.

TLV1812-EP, TLV1822-EP

SNOSDJ3 – MAY 2024

www.ti.com

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