While the front page of the datasheet (Doc Id. 19-2438; Rev 8; 4/15) indicates the input voltage range is +2.25V to +5.5V, the actual guaranteed minimum operational input voltage is +2.5V per the Electrical Characteristics Table, page 2.
History:
The datasheet Rev 8; 4/15 updated the front page Benefits and Features section, and the operating voltage was incorrectly changed from 2.5V to 5.5V to 2.25V to 5.5V.