this is the maximum electrical current the device can draw by design. To properly operate a certain drive, a power supply unit capable of delivering these currents at all given voltages is needed.
In case of the Plextor you mentioned, the power supply unit must be able to deliver 2.5A@12V PLUS 1.5A@5V.
Thank you for your helpful reply!
That is sort of what I was thinking it meant. So looking at external cases, I notice this one by cooldrives http://www.cooldrives.com/alpo5inexfia.html has an AC adapter that outputs DC 5V-1.5A / 12V-1.8A. Similarly, this enclosure from OWC http://eshop.macsales.com/item/OWC/MRSFW8U3/ lists an output supply of DC 12V-2.5A.
Based on my understanding of the listed Plextor power rating, these enclosures would not be able to power the Plextor optical drive as they don’t provide enough current (not to mention the bridge chipset + fan must require some current as well). The strange thing is that I contacted both these companies and was told by their tecnical support that their enclosures would work with all SATA Plextor and Lite-On drives.
So maybe I don’t understand the enclosure AC adapter power rating?
What am I missing here?