amis-30523 ON Semiconductor, amis-30523 Datasheet - Page 18

• Manufacturer Part Number: amis-30523
• Description: Amis-30523 Product Preview Can Micro-stepping Motor Driver
• Manufacturer: ON Semiconductor

Automatic Duty Cycle Adaptation
duty cycle of the PWM is adapted automatically to >50% to
maintain the requested average current in the coils. This
Step Translator and Step Mode
means of SPI register Stepmode: SM[2:0], SPI register
DIRCNTRL and input pins DIR and NXT. It is translating
consecutive steps in corresponding currents in both motor
coils for a given step mode.
through SPI−bits SM[2:0] (see Table 15 SPI Control
Parameter Overview ) After power−on or hard reset, the
coil−current translator is set to the default 1/32
micro−stepping at position ‘0’. Upon changing the step
mode, the translator jumps to position 0* of the
In case the supply voltage is lower than 2 * Bemf, then the
The step translator provides the control of the motor by
One out of seven possible stepping modes can be selected
Icoil
Duty Cycle
T
< 50%
PWM
Actual value
Figure 15. Automatic Duty Cycle Adaption
Duty Cycle >50%
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process is completely automatic and requires no additional
parameters for operation. The over−all current−ripple is
divided by two if PWM frequency is doubled (see Table 15
SPI Control Parameter Overview PWMF)
corresponding stepping mode. When remaining in the same
step mode, subsequent translator positions are all in the same
column and increased or decreased with 1. Table 12 lists the
output current vs. the translator position.
projected approximately on a circle in the (I
There are, however, two exceptions: uncompensated half
step and full step. In these step modes the currents are not
regulated to a fraction of I
regulated at 100%. In the (I
projected on a square. Table 11 lists the output current vs. the
translator position for these cases.
As shown in Figure 16 the output current−pairs can be
Duty Cycle < 50%
max
x
,I
but are in all intermediate steps
y
) plane the current−pairs are
Set value
x
t
,I
y
) plane.