TPS621x0A-Q1 supports 0.9 V as a minimum output with a 1.8% Vout accuracy combined with the accuracy of the two feedback resistors used. This covers a lot of use cases, however not all. There are applications that require lower than a 0.9-V output voltage, or a tighter spec for Vout accuracy and have previously been unable to use the TPS621x0A-Q1 because of these requirements. TPS629xx-Q1 opens up the opportunity for these applications to take advantage of its high-performance feature set by supporting as low as 0.4 V output voltage when using VSET and as low as 0.6 V using the feedback resistor option with a 1.25% FB accuracy across full temperature range. If VSET option is selected, the external resistors are not needed and thus the total system accuracy is improved for the fact that the external feedback resistor accuracy is no longer added to the feedback loop.