DRV8818_15 Datasheet, PDF (14/31 Pages) Texas Instruments – DRV8818 Stepper Motor Controller IC

DRV8818
SLVSAX9D – SEPTEMBER 2011 – REVISED JANUARY 2015
www.ti.com
FULL STEP
USM = 00
1/2 STEP
USM = 01
1
1
2
3
2
4
5
3
6
7
4
8
Table 2. Microstepping Indexer
1/4 STEP
USM = 10
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1/8 STEP
USM = 11
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
AOUTx
BOUTx
CURRENT
CURRENT
(% FULL-SCALE) (% FULL-SCALE)
100
0
98
20
92
38
83
56
71
71
56
83
38
92
20
98
0
100
–20
98
–38
92
–56
83
–71
71
–83
56
–92
38
–98
20
–100
0
–98
–20
–92
–38
–83
–56
–71
–71
–56
–83
–38
–92
–20
–98
0
–100
20
–98
38
–92
56
–83
71
–71
83
–56
92
–38
98
–20
STEP ANGLE
(°)
0
11.325
22.5
33.75
45 (home state)
56.25
67.5
78.75
90
101.25
112.5
123.75
135
146.25
157.5
168.75
180
191.25
202.5
213.75
225
236.25
247.5
258.75
270
281.25
292.5
303.75
315
326.25
337.5
348.75
8.3.5 Protection Circuits
8.3.5.1 Overcurrent Protection (OCP)
If the current through any FET exceeds the preset overcurrent threshold, all FETs in the H-bridge will be disabled
for a period of approximately 800 µs, or until the ENABLEn pin has been brought inactive high and then back
low, or power is removed and re-applied. Overcurrent conditions are sensed in both directions; i.e., a short to
ground, supply, or across the motor winding will all result in an overcurrent shutdown.
Note that overcurrent protection does not use the current sense circuitry used for PWM current control and is
independent of the Isense resistor value or VREF voltage. Additionally, in the case of an overcurrent event, the
microstepping indexer will be reset to the home state.
8.3.5.2 Thermal Shutdown (TSD)
If the die temperature exceeds safe limits, all drivers in the device are shut down and the indexer is reset to the
home state. Once the die temperature has fallen to a safe level operation resumes.
14
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