What is the under voltage lockout (UVLO) function of eFuse IC (electronic fuses) intended to do? And how does it works?

If the input-voltage VIN drops, the subsequent circuitry may malfunction. Therefore, when VIN of eFuse IC falls below the UVLO voltage, the output of eFuse IC turnes off to prevent the subsequent circuitry from malfunctioning. The operating voltage of UVLO is set internally in the IC. In addition, hysteresis is set in UVLO to prevent chattering, etc.
However, TCKE8 series can be adjusted by connecting two resistors. 

Figure 1. Low-voltage malfunction prevention function (TCKE800/ 805/ 812 examples)
Figure 1. Low-voltage malfunction prevention function (TCKE800/ 805/ 812 examples)