The adjustable version of the LMS3635-Q1 and LMS3655-Q1 devices regulate output voltage to a level that results in the FB node being VREF, which is approximately 1 V (seeElectrical Characteristics). Output voltage given a specific feedback divider can be calculated using Equation 3:
To ensure proper behavior for all modes of operation, a 50-kΩ resistor is recommended for RFBT. RFBB can then be determined using Equation 4:
In addition, a feed-forward capacitor CFF may be required to optimize the transient response. For output voltages greater than 6 V, the WEBENCH Design Tool can be used to optimize the design.