TLV4021 datasheet(23/38 Pages) TI

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Under-Voltage

Alert

Normal Operating

Voltage

Normal Operating

Voltage

OUT

3.3V

2.03V

TLV4021, TLV4031, TLV4041, TLV4051

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SNVSB04B – MARCH 2019 – REVISED JUNE 2020

Product Folder Links: TLV4021 TLV4031 TLV4041 TLV4051

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Typical Application (continued)

(2)

For the specific undervoltage detection of 2.0 V using the TLV4041R1, the following results are calculated.

(3)

where

•

R2 is set to 1 MΩ

•

VBAT is set to 2.0 V

•

VIT- is set to1.18 V

Choose RTOTAL (R1 + R2) such that the current through the divider is at least 100 times higher than the input bias

current (IBIAS). The resistors can have high values to minimize current consumption in the circuit without adding

significant error to the resistive divider.

8.2.1.3 Application Curve

Figure 45. Under-Voltage Detection

8.2.2 Additional Application Information

8.2.2.1 Pull-up Resistor Selection

For the TLV4021 (open-drain output versions of the TLV40x1 family), care should be taken in selecting the pull-

up resistor (RPU) value to ensure proper output voltage levels. First, consider the required output high logic level

requirement of the logic device that is being driven by the comparator when calculating the maximum RPU value.

When in a logic high output state, the output impedance of the comparator is very high but there is a finite

amount of leakage current that needs to be accounted for. Use IO-LKG from the EC Table and the VIH minimum

from the logic device being driven to determine RPU maximum using Equation 4.

(4)

Next, determine the minimum value for RPU by using the VIL maximum from the logic device being driven. In

order for the comparator output to be recognized as a logic low, VIL maximum is used to determine the upper

boundary of the comparator's VOL. VOL maximum for the comparator is available in the EC Table for specific sink

current levels and can also be found from the VOUT versus ISINK curve in the Typical Application curves. A good

design practice is to choose a value for VOL maximum that is 1/2 the value of VIL maximum for the input logic

device. The corresponding sink current and VOL maximum value will be needed to calculate the minimum RPU.

This method will ensure enough noise margin for the logic low level. With VOL maximum determined and the

corresponding ISINK obtained, the minimum RPU value is calculated with Equation 5.

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