10.2.1.2 Detailed Design Procedure

Configure the circuit as shown in Figure 10-3. 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-Q1. This causes

the comparator output to transition from a logic high to a logic low. The push-pull output of the TLV3012-Q1

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

under-voltage alert signal.

Equation 2 is derived from the analysis of Figure 10-3.

(2)

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 2 and solving for R1 yields Equation 3.

(3)

For the specific undervoltage detection of 2.0 V using the TLV3012-Q1, the following results are calculated.

(4)

where

• R2 is set to 1 MΩ

• VBAT is set to 2.0 V

• VREF is set to1.242 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.

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TLV3011-Q1, TLV3012-Q1, TLV3011B-Q1, TLV3012B-Q1

SBOS551C – MARCH 2011 – REVISED APRIL 2023

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