The LMZ3 power modules have exceptional voltage reference tolerance of 1%. Check the device datasheet for more details, as usually the front page of the datasheet shows the initial accuracy, which is room temperature performance. To get a better idea of the full temperature accuracy performance, the specification table of the datasheet will reveal the information. The example shown here shows that the 0.6 V reference is 1% accurate over the entire input voltage range and temperature range. The 1% full temperature reference accuracy indicates very good performance, comparatively speaking. A more accurate reference will help the power solution to meet the total regulation accuracy requirement. Choosing a tighter tolerance resistor dividers will also help improve the accuracy of the regulator. The 0.1% resistors will cost more than 1% resistors. Resistor networks have even higher accuracy by trimming and matching temperature characteristics, but may require a special order. Improvement in voltage accuracy may bring peace of mind and the cost delta is low compared to the total cost of the DC/DC converter solution.