AMIS30421C4211G ONSEMI [ON Semiconductor], AMIS30421C4211G Datasheet - Page 14

• Manufacturer Part Number: AMIS30421C4211G
• Description: Micro-Stepping Stepper Motor Bridge Controller
• Manufacturer: ONSEMI [ON Semiconductor]

PWM Current Control
winding current (measured over the external sense resistor)
with the requested current and feeds back the information to
a digital regulation loop. This loop then generates a PWM
signal, which turns on/off the current sources (I
switches (SW
duty−cycle are synchronized to the on−chip PWM clock.
The frequency of the PWM controller is fixed and will not
vary with changes in the supply voltage. Also variations in
motor−speed or load−conditions of the motor have no effect.
There are no external components required to adjust the
PWM frequency.
means of the <PWMJ> bit.
Step Translator and Step Mode
means of the stepmode SPI bits <SM[2:0]>, the enable SPI
bit <MOTEN>, the direction SPI bit <DIRCTRL> and input
Remark:
DIR−pin = high
A PWM comparator compares continuously the actual
For EMC reasons it’s possible to add jitter to the PWM by
The step translator provides the control of the motor by
♦
♦
Figure 12. Circular representation Half−step
Figure 14. Square Representation Half−step
DIR−pin = high
Positive coil current flows from MOTXP to MOTXN and MOTYP to MOTYN.
In above figures SPI bit <DIRCTRL> is set to ‘0’. When set to ‘1’, rotation will be reversed.
Step 6
Step5
Step7
Step 6
on
Step 7
Step5
, SW
Uncompensated
off
Compensated
Start = 0
). The switching points of the PWM
Start= 0
I
I
Y
Y
Step 4
Step4
Step 1
Step 3
Step2
DIR−pin = low
Step2
Step 1
Step 3
I
I
X
X
DIR−pin = low
on
, I
off
http://onsemi.com
) and
14
DIR−pin = high
pins DIR and NXT. It is translating consecutive steps in
corresponding currents in both motor coils for a given step
mode. One out of 8 possible stepping modes can be selected
through SPI bits <SM[2:0]>.
translator is set to position 0. For all stepping modes except
full step this means that the coil current is maximum in the
Y−coil and zero in the X−coil (see Table 7). If NXT pulses
are applied when the DIR−pin is pulled low, SPI bit
<DIRCTRL> is zero and SPI bit <MOTEN> is one, the coil
current translator will step through Table 7 from top till
bottom. If DIR−pin is pulled high or SPI bit <DIRCTRL> is
set to ‘1’, the coil current translator will step in opposite
direction through the table.
stepping modes. The Y−coil current is plotted on the
Y−axes, the X−coil current on the X−axes. Notice that all
stepping modes from Table 7 can be plotted on a circle with
the exception of half step uncompensated and full step.
These are plotted on a square.
DIR−pin = high
After power−up or clear (CLR−pin) the coil current
Figures 12 up to 15 gives another view on the different
Figure 13. Circular representation 1/4
Start= 0
Step12
Step3
Step 11
Figure 15. Square Representation
Step13
Step 14
Step 10
Step 15
Step 9
Microstepping
Start = 0
Full−step
I
I
Y
Y
Step 8
Step 1
Step7
Step 2
Step 6
Step 3
Step5
Step2
Step 4
Step 1
DIR−pin = low
I
I
X
DIR−pin = low
X