CR - the rev 1 540's needed 5v+ and didn't do spindle VFD, the rev 3 540's don't need 5v - its internally generated and now do the spindle control!
And whats this 'auto motor temp control' ? there is no feed back from the motors to the controller - motors will get as hot they like given the restricted ampage being pushed through them! The 3.5A limit was only a nominal level to save on higher capacity components being needed on the boards - it is a 'budget' controller after all!
Sorry to thread jack
