LMD18245_06 Datasheet, PDF (19/21 Pages) National Semiconductor (TI) – 3A, 55V DMOS Full-Bridge Motor Driver

The Typical Application (Continued)
QUARTER STEP DRIVE WITH TORQUE
COMPENSATION
Figure 14 shows the winding currents and lookup table for a
quarter step drive (four microsteps per full step) with torque
compensation.
Top Trace: Phase A Winding Current at 1A/div
Bottom Trace: Phase B Winding Current at 1A/div
Horizontal: 2ms/div
*250 steps/second
01187826
90˚ ELECTRICAL/FULL STEP ÷ 4 MICROSTEPS/FULL STEP = 22.5˚ ELECTRICAL/MICROSTEP
α
|
0.0˚
FORWARD
22.5˚
↓
45.0˚
67.5˚
90.0˚
112.5˚
135.0˚
157.5˚
180.0˚
202.5˚
225.0˚
247.5˚
270.0˚
↑
292.5˚
REVERSE
315.0˚
|
337.5˚
REPEAT
BRAKE A = BRAKE B = 0
|cos(α)|
1
0.924
0.707
0.383
0
0.383
0.707
0.924
1
0.924
0.707
0.383
0
0.383
0.707
0.924
DA
DIRECTION A
15
1
14
1
11
1
6
1
0
0
6
0
11
0
14
0
15
0
14
0
11
0
6
0
0
1
6
1
11
1
14
1
|sin(α)|
0
0.383
0.707
0.924
1
0.924
0.707
0.383
0
0.383
0.707
0.924
1
0.924
0.707
0.383
DB
DIRECTION B
0
1
6
1
11
1
14
1
15
1
14
1
11
1
6
1
0
0
6
0
11
0
14
0
15
0
14
0
11
0
6
0
FIGURE 14. Winding Currents and Lookup Table for Quarter Step Drive with Torque Compensation
19
www.national.com