Why won't the MAX40088 output a rail-to-rail voltage in voltage follower configuration?
The MAX40088 has a rail to rail output stage, but the input common mode range is limited to VDD - 1.5V. Therefore, if the input voltage nears the upper rail, then the output will clip or distort. In order to utilize the full range of the rail to rail output stage, the op amp must be configured with higher gain, such that an input within the specified common mode range will produce the maximum output voltage swing.
