If input voltage (VIN) has noise such as ripples, it is advisable to select an LDO regulator with a high ripple rejection ratio (R.R.).
R.R. is a figure of merit that represents the capability of an LDO regulator to filter out the ripples superimposed on VIN from the output.
Use R.R. as a guide when using an LDO regulator in analog and other highly noise-sensitive circuits. In cases where an LDO regulator is preceded by a DC-DC converter, an LDO regulator with a higher R.R. is more suitable for CMOS sensor and other high-precision analog circuits because a high-R.R. LDO regulator provides an excellent noise suppression capability. The ripple rejection ratio is calculated as follows: