AMIS-30511 Datasheet, PDF (15/28 Pages) ON Semiconductor – Micro-Stepping Motor Driver

AMIS−30511
Change from lower to higher resolution
Iy
Iy
DIR
endpos
NXT2
DIR
NXT3 ^NXT1
NXT4
startpos
Ix
Ix
Change from higher to lower resolution
Iy
DIR
endpos
Iy
NXT1 _startpos ^DIR
NXT2
Ix
Ix
NXT3
Halfstep
1/4^th step
1/8^th step
Halfstep
Left: Change from lower to higher resolution. The left−hand side depicts the ending half−step position during which a new step mode
resolution was programmed. The right−hand side diagram shows the effect of subsequent NXT commands on the micro−step position.
Right: Change from higher to lower resolution. The left−hand side depicts the ending micro−step position during which a new step mode
resolution was programmed. The right−hand side diagram shows the effect of subsequent NXT commands on the half−step position.
Figure 9. NXT−Step Mode Synchronization
NOTE: It is advised to reduce the micro−stepping resolution only at micro−step positions that overlap with desired micro−step positions of
the new resolution.
Programmable Peak−Current
The amplitude of the current waveform in the motor coils
(coil peak current = Imax) is adjusted by means of an SPI
parameter “CUR[4:0]” (Table 11: SPI Control Register 0).
Whenever this parameter is changed, the coil−currents will
be updated immediately at the next PWM period. The
impedance of the bottom drivers is adapted with the current
range: See Table 4: DC Parameters.
Table 10. Programmable Peak Current CUR[4:0]
Current Range CUR[4:0] Index
Current (mA)
0
0
15
1
30
2
45
3
50
4
55
5
61
6
67
7
74
8
82
1
9
91
10
100
11
110
12
122
13
135
14
149
15
164
Current Range
2
3
CUR[4:0] Index
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
NOTE: Changing the current over different current ranges might lead to false over current triggering.
Current (mA)
181
200
221
244
269
297
328
362
400
441
487
538
594
656
724
800
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