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AMIS30623C623BRG Datasheet, PDF (31/61 Pages) ON Semiconductor – Micro-stepping Motor Driver | |||
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AMISâ30623
Motordriver
Current Waveforms in the Coils
Figure 17 below illustrates the current fed to the motor coils by the motordriver in halfâstep mode.
Ix
Coil X
Iy
t
Coil Y
Figure 17. Current Waveforms in Motor Coils X and Y in Halfstep Mode
Whereas Figure 18 below shows the current fed to the coils in 1/16th micro stepping (1 electrical period).
Coil X
Iy
Ix
t
Coil Y
Figure 18. Current Waveforms in Motor Coils X and Y in 1/16th MicroâStep Mode
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 microâstep in the Figure 18
above shows how the PWM circuit performs this regulation.
To reduce the current ripple, a higher PWM frequency is
selectable. The RAM register PWMfreq is used for this.
Table 22. PWM FREQUENCY SELECTION
PWMfreq
Applied PWM Frequency
0
22,8 kHz
1
45,6 kHz
PWM Jitter
To lower the power spectrum for the fundamental and
higher harmonics of the PWM frequency, jitter can be added
to the PWM clock. The RAM register <PWMJEn> is used
for this.
Table 23. PWM JITTER SELECTION
PWMJEn
Status
0
Single PWM frequency
1
Added jitter to PWM frequency
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