First ..this is an usb disk ..and usually it does not need an external power supply but in special cases when it is plugged in something it can not sustain it ..i understood it does have a power supply plug ..but ..I repeat ..it should work on the usb alone ..and get the power from it ..
If you experience some issues and need to know if ti will work when you power it external ..the values are written on the back of teh drive ..or near the plug ..You will only need to have the right jack ..and the voltage to match ..beware of any higher voltage ..it may damage it right the way ..