VHYST sets the value of the transition voltage required to switch the comparator output by increasing the

threshold region, thereby reducing sensitivity to noise.

8.2 Typical Application

8.2.1 Under Voltage Detection

Under-voltage detection is frequently required to alert the system that a battery voltage has dropped below the

usable voltage level.Figure 8-3 shows a simple under-voltage detection circuit using the TLV3012-EP which is

configured as a non-inverting comparator with the integrated 1.242 V reference is externally connected to the

inverting input pin (IN-).

+

–

1.242 V

ALERT

Micro-

Controller

V+

R1

R2

VBATT

TLV3012-EP

Figure 8-3. Under-Voltage Detection

8.2.1.1 Design Requirements

For this design, follow these design requirements:

• Operate from power supply that powers the microcontroller.

• Under-voltage alert is active low.

• Logic low output when VBAT is less than 2.0V.

8.2.1.2 Detailed Design Procedure

Configure the circuit as shown in Figure 8-3. Connect (V+) to VBAT which also powers the microcontroller.

Resistors R1 and R2 create the under-voltage alert level of 2.0 V. When the battery voltage sags down to 2.0

V, the resistor divider voltage crosses VREF, the 1.242 V reference threshold of the TLV3012-EP. This causes

the comparator output to transition from a logic high to a logic low. The push-pull output of the TLV3012-EP

is selected since the comparator operating voltage is shared with the microcontroller which is receiving the

under-voltage alert signal.

Equation 1 is derived from the analysis of Figure 8-3.

(1)

where

• R1 and R2 are the resistor values for the resistor divider connected to IN+

• VBAT is the voltage source that is being monitored for an undervoltage condition.

• VREF is the falling edge threshold where the comparator output changes state from high to low

Rearranging Equation 1 and solving for R1 yields Equation 2.

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TLV3011-EP, TLV3012-EP

SGLS349A – OCTOBER 2006 – REVISED MAY 2023

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