9.2 Typical Application

9.2.1 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 9-4 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.

V

BAT

IN

OUT

V+

s5

ALERT

3.3V

Micro-

controller

V+

1.2V

+

t

TLV4041R1

R

1

R

2

Figure 9-4. Under-Voltage Detection

9.2.1.1 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.

9.2.1.2 Detailed Design Procedure

Configure the circuit as shown in Figure 9-4. Connect (V+) to 3.3 V which also powers the micro-controller.

to 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

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

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TLV4021, TLV4031, TLV4041, TLV4051

SNVSB04C – MARCH 2019 – REVISED DECEMBER 2021

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