Note: This can be done with multiple power pellets and cubes as long as it's still active from the first power pellet.This achievement ain't bad as it seems, I find it best to stay on one side and go for ghosts on your side while leading yourself to the nearest power pellet (Sphere shape). It will max out the meter again whereas the cubes will only add a fraction, and eating ghosts will also add a little.
@Ham Salad - "when you first eat a power pellet (sphere), any other power up on the stage turns into a power pellet (cube), giving you more chances to extend your time. It's also a good idea to wait to start this until you start having Sue (purple) and Funky (green) ghosts appear, as Sue appears in groups of three, and Funkys appear in fours."
Sometimes its best to avoid ghosts that seem close but you wanna focus on moving up the field to pick up the pellets.
It's a little luck based to find a bunch of ghosts in one area, but you should eventually get it while working towards fully upgrading all power ups.
Here is a link of me getting 19 for this achievement.