JAJSM96 may 2023 DRV8849
PRODUCTION DATA
Built-in indexer logic in the DRV8849 allows a number of different step modes. The MODE0 and MODE1 pins are used to configure the step mode as shown in Table 8-2. The settings can be changed on the fly.
| MODE0x | MODE1x | STEP MODE |
|---|---|---|
| 0 | 0 | Full step (2-phase excitation) with 100% current |
| 0 | 330 kΩ to GND | Full step (2-phase excitation) with 71% current |
| 1 | 0 | Non-circular 1/2 step |
| Hi-Z | 0 | 1/2 step |
| 0 | 1 | 1/4 step |
| 1 | 1 | 1/8 step |
| Hi-Z | 1 | 1/16 step |
| 0 | Hi-Z | 1/32 step |
| Hi-Z | 330 kΩ to GND | 1/64 step |
| Hi-Z | Hi-Z | 1/128 step |
| 1 | Hi-Z | 1/256 step |
Table 8-3 shows the relative current and step directions for full-step (71% current), 1/2 step, 1/4 step and 1/8 step operation. Higher microstepping resolutions follow the same pattern. The OUTxA current is the sine of the electrical angle and the OUTxB current is the cosine of the electrical angle. Positive current is defined as current flowing from the OUTxA pin to the OUTxB pin while driving.
At each rising edge of the STEP input the indexer travels to the next state in the table. The direction is shown with the DIR pin logic high. If the DIR pin is logic low, the sequence is reversed.
If the step mode is changed on the fly while stepping, the indexer advances to the next valid state for the new step mode setting at the rising edge of STEP.
The initial excitation state is an electrical angle of 45°, corresponding to 71% of full-scale current in both coils. This state is entered after power-up, after exiting logic undervoltage lockout, or after exiting sleep mode.
| 1/8 STEP | 1/4 STEP | 1/2 STEP | FULL STEP 71% | OUTxA CURRENT (% FULL-SCALE) | OUTxB CURRENT (% FULL-SCALE) | ELECTRICAL ANGLE (DEGREES) |
|---|---|---|---|---|---|---|
| 1 | 1 | 1 | 0% | 100% | 0.00 | |
| 2 | 20% | 98% | 11.25 | |||
| 3 | 2 | 38% | 92% | 22.50 | ||
| 4 | 56% | 83% | 33.75 | |||
| 5 | 3 | 2 | 1 | 71% | 71% | 45.00 |
| 6 | 83% | 56% | 56.25 | |||
| 7 | 4 | 92% | 38% | 67.50 | ||
| 8 | 98% | 20% | 78.75 | |||
| 9 | 5 | 3 | 100% | 0% | 90.00 | |
| 10 | 98% | -20% | 101.25 | |||
| 11 | 6 | 92% | -38% | 112.50 | ||
| 12 | 83% | -56% | 123.75 | |||
| 13 | 7 | 4 | 2 | 71% | -71% | 135.00 |
| 14 | 56% | -83% | 146.25 | |||
| 15 | 8 | 38% | -92% | 157.50 | ||
| 16 | 20% | -98% | 168.75 | |||
| 17 | 9 | 5 | 0% | -100% | 180.00 | |
| 18 | -20% | -98% | 191.25 | |||
| 19 | 10 | -38% | -92% | 202.50 | ||
| 20 | -56% | -83% | 213.75 | |||
| 21 | 11 | 6 | 3 | -71% | -71% | 225.00 |
| 22 | -83% | -56% | 236.25 | |||
| 23 | 12 | -92% | -38% | 247.50 | ||
| 24 | -98% | -20% | 258.75 | |||
| 25 | 13 | 7 | -100% | 0% | 270.00 | |
| 26 | -98% | 20% | 281.25 | |||
| 27 | 14 | -92% | 38% | 292.50 | ||
| 28 | -83% | 56% | 303.75 | |||
| 29 | 15 | 8 | 4 | -71% | 71% | 315.00 |
| 30 | -56% | 83% | 326.25 | |||
| 31 | 16 | -38% | 92% | 337.50 | ||
| 32 | -20% | 98% | 348.75 |
Table 8-4 shows the full step operation with 100% full-scale current. This stepping mode consumes more power than full-step mode with 71% current, but provides a higher torque at high motor RPM.
| FULL STEP 100% | OUTxA CURRENT (% FULL-SCALE) | OUTxB CURRENT (% FULL-SCALE) | ELECTRICAL ANGLE (DEGREES) |
|---|---|---|---|
| 1 | 100 | 100 | 45 |
| 2 | 100 | -100 | 135 |
| 3 | -100 | -100 | 225 |
| 4 | -100 | 100 | 315 |
Table 8-5 shows the noncircular 1/2–step operation. This stepping mode consumes more power than circular 1/2-step operation, but provides a higher torque at high motor RPM.
| NON-CIRCULAR 1/2-STEP | OUTxA CURRENT (% FULL-SCALE) | OUTxB CURRENT (% FULL-SCALE) | ELECTRICAL ANGLE (DEGREES) |
|---|---|---|---|
| 1 | 0 | 100 | 0 |
| 2 | 100 | 100 | 45 |
| 3 | 100 | 0 | 90 |
| 4 | 100 | –100 | 135 |
| 5 | 0 | –100 | 180 |
| 6 | –100 | –100 | 225 |
| 7 | –100 | 0 | 270 |
| 8 | –100 | 100 | 315 |