#FIG_CYS_5BP_BSB shows the motor-start sequence implemented in the MCT8329A device.
Figure 7-16 Motor Starting-Up Flow
Power-On StateThis is the initial state of the Motor Start Sequence (MSS). The MSS starts in this state on initial power-up or whenever the MCT8329A device comes out of standby or sleep mode.
DIR Change JudgementIn MCT8329A, if direction change command is detected at start of MSS, the motor direction detected in ISD is assumed to be opposite to commanded direction and reverse drive is performed if RVS_DR_EN is set to 1b.
ISD_EN JudgementAfter power-on, the MCT8329A MSS enters the ISD_EN judgement where it checks to see if the initial speed detect (ISD) function is enabled (ISD_EN = 1b). If ISD is disabled, the MSS proceeds directly to the BRAKE_EN judgement. If ISD is enabled, MSS advances to the ISD (Is Motor Stationary) state.
ISD StateThe MSS determines the initial condition (speed, direction of spin) of the motor (see GUID-A7E6B9C4-BDB0-4CDB-9AE2-3322EC883456.html#TITLE-SLVSEX6SLVSCP23770). If motor is deemed to be stationary (motor BEMF < STAT_DETECT_THR), the MSS proceeds to STAT_BRK_EN judgement. If the motor is not stationary, MSS proceeds to verify the direction of spin.
STAT_BRK_EN JudgementThe MSS checks if the stationary brake function is enabled (STAT_BRK_EN =1b). If the stationary brake function is enabled, the MSS advances to the stationary brake routine. If the stationary brake function is disabled, the MSS advances to motor start-up state (see GUID-BABD1783-A1AD-45CB-ADFE-A0F8976C50BA.html).
Stationary Brake RoutineThe stationary brake routine can be used to ensure the motor is completely stationary before attempting to start the motor. The stationary brake is applied by turning on all three low-side driver MOSFETs for a time configured by STARTUP_BRK_TIME.
Direction of Spin JudgementThe MSS determines whether the motor is spinning in the forward or the reverse direction. If the motor is spinning in the forward direction, the MCT8329A proceeds to the RESYNC_EN judgement. If the motor is spinning in the reverse direction, the MSS proceeds to the RVS_DR_EN judgement.
RESYNC_EN JudgementIf RESYNC_EN is set to 1b, MCT8329A proceeds to BEMF > RESYNC_MIN_THRESHOLD judgement. If RESYNC_EN is set to 0b, MSS proceeds to HIZ_EN judgement.
BEMF > RESYNC_MIN_THRESHOLD JudgementIf motor speed is such that BEMF > RESYNC_MIN_THRESHOLD, MCT8329A uses the speed and position information from the ISD state to transition to the closed loop state (see GUID-74941E73-0BD9-4B9A-8B2B-D1495192FD6B.html#TITLE-SLVSEX6SLVSCP23552 ) directly. If BEMF < RESYNC_MIN_THRESHOLD, MCT8329A proceeds to STAT_BRK_EN judgement.
RVS_DR_EN JudgementThe MSS checks to see if the reverse drive function is enabled (RVS_DR_EN = 1). If it is enabled, the MSS transitions to check speed of the motor in reverse direction. If the reverse drive function is not enabled, the MSS advances to the HIZ_EN judgement.
Speed > Open to Closed Loop Handoff JudgementThe MSS checks to see if the reverse speed is high enough for MCT8329A to decelerate in closed loop. Till the speed (in reverse direction) is high enough, MSS stays in reverse closed loop deceleration. If speed is too low, then the MSS transitions to reverse open loop deceleration.
Reverse Closed Loop, Open Loop Deceleration and Zero Speed CrossoverThe MCT8329A resynchronizes in the reverse direction, decelerates the motor in closed loop till motor speed falls below the handoff threshold. (see GUID-08DD7074-E931-4A8E-83FE-B4529D528406.html#TITLE-SLVSEX6SLVSCP2836). When motor speed in reverse direction is too low, the MCT8329A switches to open-loop, decelerates the motor in open-loop, crosses zero speed, and accelerates in the forward direction in open-loop before entering closed loop operation after motor speed is sufficiently high.
HIZ_EN JudgementThe MSS checks to determine whether the coast (Hi-Z) function is enabled (HIZ_EN =1). If the coast function is enabled, the MSS advances to the coast routine. If the coast function is disabled, the MSS advances to the BRAKE_EN judgement.
Coast (Hi-Z) RoutineThe device coasts the motor by turning OFF all six MOSFETs for a certain time configured by HIZ_TIME.
BRAKE_EN JudgementThe MSS checks to determine whether the brake function is enabled (BRAKE_EN =1). If the brake function is enabled, the MSS advances to the brake routine. If the brake function is disabled, the MSS advances to the motor start-up state (see GUID-BABD1783-A1AD-45CB-ADFE-A0F8976C50BA.html).
Brake Routine Brake is applied either using high-side or low-side MOSFETs based on BRK_MODE configuration.
Closed Loop StateIn this state, the MCT8329A drives the motor with trapezoidal control.