UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
Configure the circuit as shown in Figure 44. Connect (V+) to 3.3 V which also powers the micro-controller. 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 the (VIT-) threshold of the TLV4041R1. This causes the comparator output 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 the circuit. Error at the falling edge threshold of (VIT-) is amplified by the inverse of the resistor divider ratio. So minimizing the resistor divider ratio is a way of optimizing voltage monitoring accuracy.
For the specific undervoltage detection of 2.0 V using the TLV4041R1, the following results are calculated.
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.