AMIS-30624 Datasheet, PDF (31/56 Pages) AMI SEMICONDUCTOR – I2C Microstepping Motordriver

AMIS-30624
14.3 Motor Driver
14.3.1. Current Waveforms in the Coils
Figure 18 illustrates the current fed to the motor coils by the motor driver in half step mode.
Ix
Iy
Coil X
t
Coil Y
PC20051205.1
Figure 18: Current Waveforms in Motorcoils X and Y in Halfstep Mode
Whereas Figure 19 below shows the current fed to one coil in 1/16^th micro stepping (one electrical period).
Ix
Iy
Coil X
t
Coil Y
PC20051123.4
Figure 19: Current Waveforms in Motorcoils X and Y in 1/16^th Microstep mode
14.3.2. PWM Regulation
In order to force a given current (determined by Irun or Ihold and the current position of the rotor) through the motor coil while ensuring
high energy transfer efficiency, a regulation based on PWM principle is used. The regulation loop performs a comparison of the sensed
output current to an internal reference, and features a digital regulation generating the PWM signal that drives the output switches. The
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