V

BAT

IN

OUT

V+

s5

ALERT

3.3V

Micro-

controller

V+

1.2V

+

t

TLV4041R1

R

1

R

2

22

TLV4021, TLV4031, TLV4041, TLV4051

SNVSB04B – MARCH 2019 – REVISED JUNE 2020

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Product Folder Links: TLV4021 TLV4031 TLV4041 TLV4051

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Copyright © 2019–2020, Texas Instruments Incorporated

8.2 Typical Application

8.2.1 Under-Voltage Detection

Under-voltage detection is frequently required in battery-powered, portable electronics to alert the system that a

battery voltage has dropped below the usable voltage level. Figure 44 shows a simple under-voltage detection

circuit using the TLV4041R1 which is a non-inverting comparator with an integrated 1.2 V reference and a push-

pull output stage. The non-inverting TLV4041 option was selected in this example since the micro-controller

required an active low signal when an undervoltage level occurs. However, if an active high signal was required,

the TLV4051 option with an inverting input stage would be utilized.

Figure 44. Under-Voltage Detection

8.2.1.1 Design Requirements

For this design, follow these design requirements:

•

Operate from 3.3 V power supply that powers the microcontroller.

•

Under-voltage alert is active low.

•

8.2.1.2 Detailed Design Procedure

Configure the circuit as shown in Figure 44. Connect (V+) to 3.3 V which also powers the micro-controller.

transition from a logic high to a logic low. The push-pull option of the TLV40x1 family is selected since the

comparator operating voltage is shared with the microcontroller which is receiving the under-voltage alert signal.

The TLV4041 option with the 1.2 V internal reference is selected because it is the closest internal reference

option that is less than the critical under-voltage level of 2.0 V. Choosing the internal reference option that is

closest to the critical under-voltage level minimizes the resistor divider ratio which optimizes the accuracy of the

minimizing the resistor divider ratio is a way of optimizing voltage monitoring accuracy.

Equation 1 is derived from the analysis of Figure 44.

(1)

where

•

•

•