RMS Technologies R256 CONTROLLER/DRIVER - Manual (Page 25)

Peak current versus Amps/Phase
Where does the 1.4 times come from? Current is continuously changing when a
motor steps. If the motor is rated for 1.0 A/Ph, it may receive 0 Amps, 1 Amp, 1.4
Amps, or anything in between if you are microstepping. For ease of explanation, we
will look at the current waveform when we half step, or set the driver/controller to 2x
microstepping.
If we take a look at both the A and B phases, and plot on an X-Y chart of when each
phase receives current, and how much it receives, it will look like the chart below.
Beginning at position 1, Phase A receives negative current, and Phase B receives
positive current. Let’s assume it is at coordinate (-1, 1).
The position versus time graph just above, plots only the A Phase, following the eight
different steps the motor will make. Current is changing with each position. Recall
that a negative in electronics simply means reverse direction of current flow.
RMS Technologies Page 25 Version 1.05
R256 Controller Manual 4/3/2009