Linear voltage regulators, including LDO (Low Drop Out) types, are used to provide a stable output voltage that is nominally invariant with respect to changes in load current, input voltage, or environmental factors. Their operating principle requires that the input voltage be maintained above the desired output voltage by some minimum amount, and function on the basis of converting whatever excess voltage is present at the input to heat. While this renders them less efficient than switch-mode voltage regulators for most applications, they are often better suited for applications with high sensitivity to noise.