ZHCSH31B August 2017 – February 2018 DRV10987
PRODUCTION DATA.
After it is determined that the motor is stationary and after completing the motor initialization with either align or IPD, the DRV10987 device begins to accelerate the motor. This acceleration is accomplished by applying a voltage determined by the open-loop current setting (OpenLCurr[1:0]) to the appropriate drive state and by increasing the rate of commutation without regard to the real position of the motor (referred to as open-loop operation). The function of the open-loop operation is to drive the motor to a minimum speed so that the motor generates sufficient BEMF to allow the commutation control logic to accurately drive the motor.
Table 5 lists the configuration options that can be set in the register to optimize the initial motor acceleration stage for different applications.
| DESCRIPTION | REG. NAME | CONFIGURATION BITS | MIN. VALUE | MAX. VALUE |
|---|---|---|---|---|
| Open- to closed-loop threshold | CONFIG4 | Op2ClsThr[4:0] | 0.8 Hz | 204.8 Hz |
| Align time | CONFIG4 | AlignTime[2:0] | 40 ms | 5.3 s |
| First-order acceleration coefficient | CONFIG4 | StAccel[2:0] | 0.019 Hz/s | 76 Hz/s |
| Second-order acceleration coefficient | CONFIG4 | StAccel2[2:0] | 0.0026 Hz/s2 | 57 Hz/s2 |
| Open-loop current setting | CONFIG3 | OpenLCurr[1:0] | 200 mA | 1.6 A |
| Align current setting | 150 mA | 1.2 A | ||
| Open-loop current ramping | CONFIG3 | OpLCurrRt[2:0] | 0.023 VCC/s | 6 VCC/s |