AMIS-30621 Datasheet, PDF (34/43 Pages) AMI SEMICONDUCTOR – LIN Microstepping Motordriver

AMIS-30621 LIN Microstepping Motordriver
9.2.3 Motordriver
9.2.3.1 Current Waveforms in the Coils
The figure below illustrates the current fed to the motor
coils by the motordriver in half-step mode.
Data Sheet
Whereas the figure below shows the current fed to one coil
in 1/16^th microstepping (1 electrical period).
9.2.3.2 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 zoom over one micro-step in the figure above shows
how the PWM circuit performs this regulation.
9.2.3.3 Motor Starting Phase
At motion start, the currents in the coils are directly
switched from Ihold to Irun with a new sine/cos ratio
corresponding to the first half (or micro) step of the motion.
AMI Semiconductor- Rev. 1.4
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