Looking for buck voltage regulator

I am looking for a step up/down voltage regulator that will engage at 3 volts i have only found ones that engage at 4.5 or higher. Any help is appreciated

Hello,
Welcome to the DigiKey TechForum. Are you looking for something similar to this group of regulators? Please explain your application in detail so we can narrow down some options. Do you have an example part number for the 4.5 volt version we can use as reference? What is the voltage output you are looking for?