SLVSE57C June 2017 – April 2018 TPS2595
The undervoltage lockout (UVLO) trip point is adjusted using the external voltage divider network of R1 and R2 as connected between IN, EN/UVLO and GND pins of the device. The values required for setting the undervoltage are calculated solving Equation 7.
Where VUVLO(R) is UVLO rising threshold (1.2 V). Because R1 and R2 leak the current from input supply VIN, these resistors must be selected based on the acceptable leakage current from input power supply VIN.
The current drawn by R1 and R2 from the power supply is IR12 = VIN / (R1 + R2).
However, leakage currents due to external active components connected to the resistor string can add error to these calculations. So, the resistor string current, IR12 must be chosen to be 20 times greater than the leakage current expected.
To set the UVLO at VUVR = 4.3 V, select R2 = 387 kΩ, and R1 = 1 MΩ.