Just to be completely sure - power supply size

Ok, I've manage to mis-remember this stuff before so I'd better
check.

Reading the Gecko stepper motor white paper, its says Bipolar motors
use 1/3 of their rated amperage. With this in mind, If I have three
2.5A motors, the power supply needs to be (minimum) 2.5A - not
3x2.5A. Is this correct?

If so, I'd likely go up to a 3A or 4A transformer just to be safe.

I'm converting my A3977 based 3 axis driver schematic to opto-
isolation. I'll post it for (brutal) scrutiny later today.