C1

100 pF

+

±

R1

100 kŸ

VCC

R2

100 kŸ

OUT

VA

VC

t1

t2

0

V

+

R3

100 kŸ

R4

100 kŸ

RPU

10 kŸ

V

+

OUT

16

LM393LV-Q1

SNOSDB3 – JUNE 2020

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Typical Applications (continued)

10.2.1.1 Design Requirements

For this design, follow these design requirements:

•

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

•

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

•

Alert signal is active low

•

Operate from a 3.3-V power supply

10.2.1.2 Detailed Design Procedure

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

minimize power consumption. The resistor values may 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 1.1 V or greater than 2.2 V. The

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

"window"), as shown in Figure 9.

10.2.1.3 Application Curve

Figure 9. Window Comparator Results

For more information, please see Application note SBOA221 "Window comparator circuit".

10.2.2 Square-Wave Oscillator

Square-wave oscillator can be used as low cost timing reference or system supervisory clock source.

Figure 10. Square-Wave Oscillator