The LMZM33602 implements internal UVLO circuitry on the VIN pin. The device is disabled when the VIN pin voltage falls below the internal VIN UVLO threshold. The internal VIN UVLO rising threshold is 3.9 V (maximum) with a typical hysteresis of 300 mV.

If an application requires a higher UVLO threshold, a resistor divider can be placed on the EN/SYNC pin as shown in Figure 7-13. Table 7-6 lists recommended resistor values for R_ENT and R_ENB to adjust the ULVO voltage.

To ensure proper start-up and reduce input current surges, the UVLO threshold must be set to at least (V_OUT + 1.5 V) for output voltages ≤ 5 V and at least (1.3 × V_OUT) for output voltages > 5 V. TI recommends to set the UVLO threshold to approximately 80% to 85% of the minimum expected input voltage.

Figure 7-13 Adjustable UVLO