After the motor is confirmed to be stationary and after completing the motor initialization, the DRV10974 device begins to accelerate the motor. This acceleration is accomplished by applying a voltage to the motor at the appropriate drive state and increasing the rate of commutation without regard to the actual 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 drive the motor accurately.

The motor start-up profile can be configured using an external resistor to set the acceleration profile before transitioning to closed-loop operation. #T4509467-64 shows this acceleration profile. During closed-loop operation the RMP pin controls the closed-loop acceleration and deceleration. Table 7-2 lists the selectable acceleration parameters.

Figure 7-14 Start-Up Profile