AMIS-30623 Datasheet, PDF (34/65 Pages) AMI SEMICONDUCTOR – LIN Microstepping Motordriver

AMIS-30623
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. To reduce the current ripple, a
higher PWM frequency should be selectable. The RAM register PWMfreq is used for this (Bit 0 in Data 8 of SetMotorParam).
Table 22: PWM Frequency Selection
PWMfreq
Applied PWM Frequency
0
22.8 kHz
1
45.6 kHz
14.3.3. 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. (Bit 0 in Data 8 of SetStallParam). Readout with GetFullStatus (Bit 0 Data 8 IFR 2).
Table 23: PWM Jitter Selection
PWMJEn
Status
0
Single PWM frequency
1
Added jitter to PWM frequency
14.3.4. Motor Starting Phase
At motion start, the currents in the coils are directly switched from Ihold to Irun with a new sine/cosine ratio corresponding to the first
half (or micro) step of the motion.
14.3.5. Motor Stopping Phase
At the end of the deceleration phase, the currents are maintained in the coils at their actual DC level (hence keeping the sine/cosine
ratio between coils) during the stabilization time t_stab(see AC Table). The currents are then set to the hold values,
respectively Ihold x sin(TagPos) and Ihold x cos(TagPos) as illustrated below. A new positioning order can then be executed.
Ix
Iy
t
Figure 22: Motor Stopping Phase
t_stab
PC20051123.5
14.3.6. Charge Pump Monitoring
If the charge pump voltage is not sufficient for driving the high side transistors (due to a failure), an internal HardStop command is
issued. This is acknowledged to the master by raising flag <CPFail> (available with command GetFullStatus).
In case this failure occurs while a motion is ongoing, the flag <StepLoss> is also raised.
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