SLLSFT3 November 2025 MC121-Q1
ADVANCE INFORMATION
MC121-Q1 provides the option of compensating the offset between Hall sensor and BEMF zero cross due to the relative location of the Hall sensor (in MC121-Q1) with respect to the BEMF zero cross. HALL_OS_ANGLE can be used to set the magnitude of the Hall offset angle ranging from 0o to 43.6o in steps of 1.4o. The polarity of this offset with respect to zero cross (lead or lag) can be set using HALL_ANGLE_MODE.
A lead or lag time with respect to the Hall sensor output is needed to maximize the motor efficiency across speeds by aligning the motor phase current with BEMF. The lead/lag time (tHALL_OS_TIME) can be set by HALL_OS_TIME from 0 to 2.55ms in steps of 10µs; the polarity of this time (lead or lag) can be set using HALL_TIME_MODE.
MC121-Q1 aggregates the total lead or lag time that needs to be applied as per HALL_OS_ANGLE, HALL_ANGLE_MODE, HALL_OS_TIME and HALL_TIME_MODE and applies the computed lead or lag time around commutation region. For example, when HALL_OS_ANGLE is set to -15.4o, HALL_OS_TIME is set to 150µs, motor is operating at 500Hz, the applied lead time is approximately 64µs. 15.4o at 500Hz corresponds to 85.5µs, so effective lead/lag time is (150-85.5)µs = ~64µs.