+

±

+

±

RX

100 NŸ

RY

100 NŸ

RH

576 NŸ

5 V

VOUT

5 V

VIN

21

TLV1805

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SNOSD50A – DECEMBER 2018 – REVISED JANUARY 2020

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8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The TLV1805 family of devices can be used in a wide variety of applications, such as MOSFET gate drivers,

zero crossing detectors, window comparators, over and undervoltage detectors, and high-side voltage sense

circuits.

8.2 Typical Applications

Comparators are used to differentiate between two different signal levels. For example, a comparator

differentiates between an over-temperature and normal-temperature condition. However, noise or signal variation

at the comparison threshold causes multiple transitions. This application example sets upper and lower

hysteresis thresholds to eliminate the multiple transitions caused by noise.

Figure 66. Comparator with Hysteresis

8.2.1 Design Requirements

The design requirements are as follows:

•

Supply voltage: 5 V

•

Input: 0 V to 5 V

•

Lower threshold (VL) = 2.3 V ±0.1 V

•

Upper threshold (VH) = 2.7 V ±0.1 V

•

VH – VL = 2.4 V ±0.1 V

•

Low-power consumption

8.2.2 Detailed Design Procedure

A small change to the comparator circuit can be made to add hysteresis. Hysteresis uses two different threshold

voltages to avoid the multiple transitions introduced in the previous circuit. The input signal must exceed the

upper threshold (VH) to transition low, or below the lower threshold (VL) to transition high.

Figure 66 illustrates hysteresis on a comparator. Resistor RH sets the hysteresis level.

When the output is at a logic high (5 V), RH is in parallel with RX. This configuration drives more current into Ry,

and raises the threshold voltage (VH) to 2.7 V. The input signal must drive above VH = 2.7 V to cause the output

to transition to logic low (0 V).