SLLA663 March   2025 MCF8315A , MCF8315C , MCF8315C-Q1 , MCF8315D , MCF8316A , MCF8316C-Q1 , MCF8316D , MCF8329A , MCT8315A , MCT8316A , MCT8329A

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2End Application Configuration Recommendation
    1. 2.1 Resynchronization
    2. 2.2 Reverse Drive
    3. 2.3 Coasting (Hi-Z)
    4. 2.4 Startup Brake
    5. 2.5 Direction Change Mode
  6. 3Tuning Guidance
    1. 3.1 Initial Speed Detection Module
      1. 3.1.1 Initial Speed Detection
      2. 3.1.2 ISD Times
      3. 3.1.3 Stationary Detect Threshold
    2. 3.2 Resynchronization
      1. 3.2.1 Forward Drive Resync Threshold
      2. 3.2.2 Reverse Drive
      3. 3.2.3 Reverse Acceleration Parameters
      4. 3.2.4 Reverse Drive Current Limits
      5. 3.2.5 Reverse Drive Handoff Threshold
      6. 3.2.6 Reverse Drive Open Loop Deceleration (REV_DRV_OPEN_LOOP _DEC)
    3. 3.3 Coasting (Hi-Z)
    4. 3.4 Brake
      1. 3.4.1 Brake Config (BRK_CONFIG)
  7. 4Feature Availability of MCx Devices
    1. 4.1 FOC Family (MCF83xx devices)
    2. 4.2 TRAP Family (MCT83xx devices)
  8. 5Summary
  9. 6References

3.4 Brake

Brake is enabled to bring the motor to a stationary state before motor startup for reliable spin-up.

Table 3-5 Brake Related Configurations
Configuration Sub-Feature Description Tuning Considerations
BRAKE_EN Enables brake to make the motor stationary before going to motor startup. Usually comes into effect when ISD is disabled or when sensed BEMF is less than STAT_DETECT _THR. Keep enabled to make sure motor startup with stationary rotor
BRK_MODE Selects between high-side braking and low-side braking. Can depend on the FETs used and the FET RDSon for thermals. Current sensing for current based brake only available for low side braking.
BRK_CONFIG Allows user to choose between brake time and brake current threshold to come out of brake state Current based braking is recommended to apply brake only for the time motor is spinning. Once motor slows down and brake current fall below configured threshold, brake is released. ** Current based brake is only available for low side brake. If current based brake is set with High side braking, then device defaults to time based brake.
BRK_TIME The maximum amount of time for which the device applies brake. BRK_TIME is the maximum brake time in current based brake even if current doesn’t fall below BRK_CURR_THR. For time-based brake, BRK_TIME defines the fixed time to exit brake state Set this to be the time to stop the motor from maximum safe speed to apply brake.
BRK_CURR_THR Current threshold till which the motor performs brake This is used to exit from brake if current based braking is enabled. There is importance to make sure that BRK_CURR_THR is low enough that motor is almost stopped before exiting brake for reliable startup. Too low setting can lead to motor state being stuck in ISD till ISD_TIMEOUT due to noise. Try with lowest setting and increase if unable to exit brake on time.
BRAKE_CURRENT_PERSIST Persistence time for current below threshold during current based ISD brake Keep the persistence time high enough to avoid mis-detection due to sinusoidal nature of brake current.