SLLSFU1A December   2023  – July 2024 MCF8315C

PRODMIX  

  1.   1
  2. Features
  3. Applications
  4. Description
  5. Pin Configuration and Functions
  6. Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Characteristics of the SDA and SCL bus for Standard and Fast mode
  7. Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Output Stage
      2. 6.3.2  Device Interface
        1. 6.3.2.1 Interface - Control and Monitoring
        2. 6.3.2.2 I2C Interface
      3. 6.3.3  Step-Down Mixed-Mode Buck Regulator
        1. 6.3.3.1 Buck in Inductor Mode
        2. 6.3.3.2 Buck in Resistor mode
        3. 6.3.3.3 Buck Regulator with External LDO
        4. 6.3.3.4 AVDD Power Sequencing from Buck Regulator
        5. 6.3.3.5 Mixed Mode Buck Operation and Control
        6. 6.3.3.6 Buck Under Voltage Protection
        7. 6.3.3.7 Buck Over Current Protection
      4. 6.3.4  AVDD Linear Voltage Regulator
      5. 6.3.5  Charge Pump
      6. 6.3.6  Slew Rate Control
      7. 6.3.7  Cross Conduction (Dead Time)
      8. 6.3.8  Motor Control Input Sources
        1. 6.3.8.1 Analog Mode Motor Control
        2. 6.3.8.2 PWM Mode Motor Control
        3. 6.3.8.3 I2C based Motor Control
        4. 6.3.8.4 Frequency Mode Motor Control
        5. 6.3.8.5 Speed Profiles
          1. 6.3.8.5.1 Linear Reference Profiles
          2. 6.3.8.5.2 Staircase Reference Profiles
          3. 6.3.8.5.3 Forward-Reverse Reference Profiles
      9. 6.3.9  Starting the Motor Under Different Initial Conditions
        1. 6.3.9.1 Case 1 – Motor is Stationary
        2. 6.3.9.2 Case 2 – Motor is Spinning in the Forward Direction
        3. 6.3.9.3 Case 3 – Motor is Spinning in the Reverse Direction
      10. 6.3.10 Motor Start Sequence (MSS)
        1. 6.3.10.1 Initial Speed Detect (ISD)
        2. 6.3.10.2 Motor Resynchronization
        3. 6.3.10.3 Reverse Drive
          1. 6.3.10.3.1 Reverse Drive Tuning
      11. 6.3.11 Motor Start-up
        1. 6.3.11.1 Align
        2. 6.3.11.2 Double Align
        3. 6.3.11.3 Initial Position Detection (IPD)
          1. 6.3.11.3.1 IPD Operation
          2. 6.3.11.3.2 IPD Release Mode
          3. 6.3.11.3.3 IPD Advance Angle
        4. 6.3.11.4 Slow First Cycle Start-up
        5. 6.3.11.5 Open loop
        6. 6.3.11.6 Transition from Open to Closed Loop
      12. 6.3.12 Closed Loop Operation
        1. 6.3.12.1 Closed Loop Acceleration/Deceleration Slew Rate
        2. 6.3.12.2 Speed PI Control
        3. 6.3.12.3 Current PI Control
        4. 6.3.12.4 Torque Mode
        5. 6.3.12.5 Overmodulation
      13. 6.3.13 Motor Parameters
        1. 6.3.13.1 Motor Resistance
        2. 6.3.13.2 Motor Inductance
        3. 6.3.13.3 Motor Back-EMF constant
      14. 6.3.14 Motor Parameter Extraction Tool (MPET)
      15. 6.3.15 Anti-Voltage Surge (AVS)
      16. 6.3.16 Active Braking
      17. 6.3.17 Output PWM Switching Frequency
      18. 6.3.18 PWM Modulation Schemes
      19. 6.3.19 Dead Time Compensation
      20. 6.3.20 Motor Stop Options
        1. 6.3.20.1 Coast (Hi-Z) Mode
        2. 6.3.20.2 Low-Side Braking
        3. 6.3.20.3 Active Spin-Down
      21. 6.3.21 FG Configuration
        1. 6.3.21.1 FG Output Frequency
        2. 6.3.21.2 FG during open loop
        3. 6.3.21.3 FG during idle and fault
      22. 6.3.22 DC Bus Current Limit
      23. 6.3.23 Protections
        1. 6.3.23.1  VM Supply Undervoltage Lockout
        2. 6.3.23.2  AVDD Undervoltage Lockout (AVDD_UV)
        3. 6.3.23.3  BUCK Under Voltage Lockout (BUCK_UV)
        4. 6.3.23.4  VCP Charge Pump Undervoltage Lockout (CPUV)
        5. 6.3.23.5  Overvoltage Protection (OVP)
        6. 6.3.23.6  Overcurrent Protection (OCP)
          1. 6.3.23.6.1 OCP Latched Shutdown (OCP_MODE = 00b)
          2. 6.3.23.6.2 OCP Automatic Retry (OCP_MODE = 01b)
        7. 6.3.23.7  Buck Overcurrent Protection
        8. 6.3.23.8  Hardware Lock Detection Current Limit (HW_LOCK_ILIMIT)
          1. 6.3.23.8.1 HW_LOCK_ILIMIT Latched Shutdown (HW_LOCK_ILIMIT_MODE = 00xxb)
          2. 6.3.23.8.2 HW_LOCK_ILIMIT Automatic recovery (HW_LOCK_ILIMIT_MODE = 01xxb)
          3. 6.3.23.8.3 HW_LOCK_ILIMIT Report Only (HW_LOCK_ILIMIT_MODE = 1000b)
          4. 6.3.23.8.4 HW_LOCK_ILIMIT Disabled (HW_LOCK_ILIMIT_MODE= 1xx1b)
        9. 6.3.23.9  Motor Lock (MTR_LCK)
          1. 6.3.23.9.1 MTR_LCK Latched Shutdown (MTR_LCK_MODE = 00xxb)
          2. 6.3.23.9.2 MTR_LCK Automatic Recovery (MTR_LCK_MODE= 01xxb)
          3. 6.3.23.9.3 MTR_LCK Report Only (MTR_LCK_MODE = 1000b)
          4. 6.3.23.9.4 MTR_LCK Disabled (MTR_LCK_MODE = 1xx1b)
        10. 6.3.23.10 Motor Lock Detection
          1. 6.3.23.10.1 Lock 1: Abnormal Speed (ABN_SPEED)
          2. 6.3.23.10.2 Lock 2: Abnormal BEMF (ABN_BEMF)
          3. 6.3.23.10.3 Lock3: No-Motor Fault (NO_MTR)
        11. 6.3.23.11 Minimum VM (undervoltage) Protection
        12. 6.3.23.12 Maximum VM (overvoltage) Protection
        13. 6.3.23.13 MPET Faults
        14. 6.3.23.14 IPD Faults
        15. 6.3.23.15 Thermal Warning (OTW)
        16. 6.3.23.16 Thermal Shutdown (TSD)
    4. 6.4 Device Functional Modes
      1. 6.4.1 Functional Modes
        1. 6.4.1.1 Sleep Mode
        2. 6.4.1.2 Standby Mode
        3. 6.4.1.3 Fault Reset (CLR_FLT)
    5. 6.5 External Interface
      1. 6.5.1 DRVOFF Functionality
      2. 6.5.2 DAC output
      3. 6.5.3 Oscillator Source
        1. 6.5.3.1 External Clock Source
      4. 6.5.4 External Watchdog
    6. 6.6 EEPROM access and I2C interface
      1. 6.6.1 EEPROM Access
        1. 6.6.1.1 EEPROM Write
        2. 6.6.1.2 EEPROM Read
      2. 6.6.2 I2C Serial Interface
        1. 6.6.2.1 I2C Data Word
        2. 6.6.2.2 I2C Write Transaction
        3. 6.6.2.3 I2C Read Transaction
        4. 6.6.2.4 I2C Communication Protocol Packet Examples
        5. 6.6.2.5 I2C Clock Stretching
        6. 6.6.2.6 CRC Byte Calculation
  8. EEPROM (Non-Volatile) Register Map
    1. 7.1 Algorithm_Configuration Registers
    2. 7.2 Fault_Configuration Registers
    3. 7.3 Hardware_Configuration Registers
    4. 7.4 Internal_Algorithm_Configuration Registers
  9. RAM (Volatile) Register Map
    1. 8.1 Fault_Status Registers
    2. 8.2 System_Status Registers
    3. 8.3 Device_Control Registers
    4. 8.4 Algorithm_Control Registers
    5. 8.5 Algorithm_Variables Registers
  10. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Application Curves
        1. 9.2.1.1 Motor startup
        2. 9.2.1.2 MPET
        3. 9.2.1.3 Dead time compensation
        4. 9.2.1.4 Auto handoff
        5. 9.2.1.5 Anti voltage surge (AVS)
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Bulk Capacitance
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Thermal Considerations
        1. 9.4.2.1 Power Dissipation
  11. 10Device and Documentation Support
    1. 10.1 Support Resources
    2. 10.2 Trademarks
    3. 10.3 Electrostatic Discharge Caution
    4. 10.4 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

Motor Parameter Extraction Tool (MPET)

The MCF8315C uses motor winding resistance, motor winding inductance and Back-EMF constant to estimate motor position in closed loop operation. The MCF8315C has capability of automatically measuring motor parameters in offline state, rather than having the user enter the values themselves. The MPET routine measures motor winding resistance, inductance, back EMF constant and mechanical load inertia and frictional coefficients. Offline measurement of parameters takes place before normal motor operation. TI recommends to estimate the motor parameters before motor start-up to minimize the impact caused due to possible parameter variations.

Figure 6-41 shows the sequence of operation in the MPET routine. The MPET routine is entered when either the MPET_CMD bit is set to 1b or a non-zero target speed is set. The MPET routine consists of four steps namely, IPD, Open Loop Acceleration, Current Ramp Down and Coasting. Each one of these steps are executed if the condition shown below the step evaluates to TRUE; if the condition evaluates to FALSE, the algorithm bypasses that particular step and moves on to the next step in the sequence. Once all the 4 steps are completed (or bypassed), the algorithm exits the MPET routine. If target speed is set to a non-zero value, the algorithm begins the start-up and acceleration sequence (to target speed reference) once MPET routine is exited.

MCF8315C MPET SequenceFigure 6-41 MPET Sequence

TI proprietary MPET routine includes following sequence of operation.

  • IPD: The MPET routine starts with IPD, if the user enables motor winding resistance or inductance measurement by setting MPET_R = 1b and MPET_L = 1b or if the user defines MOTOR_RES = 0 or MOTOR_IND = 0. The IPD during MPET can be configured using MPET specific configuration parameters or using the normal motor operation IPD configuration parameters. The IPD configuration selection is done using MPET_IPD_SELECT. With MPET_IPD_SELECT = 1b, the IPD current limit is configured using MPET_IPD_CURRENT_LIMIT and the IPD repeat number is configured using MPET_IPD_FREQ. With MPET_IPD_SELECT = 0b, the IPD current limit and the repeat number is configured using IPD_CURR_THR and IPD_REPEAT. The IPD timer over flow or the IPD current decay time more than three times the current ramp up time can result in MPET_IPD_FAULT. TI recommends to run the MPET multiple times to observe for consistent resistance and inductance reading.
  • Open loop Acceleration:

    After IPD, the MPET routine run align and then open loop acceleration if the back-EMF constant or mechanical parameter measurement are enabled by setting MPET_KE = 1b and MPET_MECH = 1b. The MPET routine incorporates the sequences for mechanical parameter measurement, if the speed loop PI constants are defined as zero, even if MPET_MECH = 0b. User can configure MPET specific open loop configuration parameters or use normal motor operation open loop configuration parameters. The open loop configuration selection is done using MPET_KE_MEAS_PARAMETER_SELECT. With MPET_KE_MEAS_PARAMETER_SELECT = 1b, the speed slew rate is defined using MPET_OPEN_LOOP_SLEW_RATE, the open loop current reference is defined using MPET_OPEN_LOOP_CURR_REF and the open loop speed reference is defined using MPET_OPEN_LOOP_SPEED_REF. With MPET_KE_MEAS_PARAMETER_SELECT = 0b, the speed slew rate is defined using OL_ACC_A1 and OL_ACC_A2, 80% of ILIMIT for current reference and 50% of MAX_SPEED for speed reference.

  • Current Ramp Down: After open loop acceleration, if the mechanical parameter measurement is enabled, then the MPET routine optimizes the motor current to lower value sufficient to support the load. If mechanical parameter measurement is disabled (MPET_MECH = 0b, or non-zero speed loop PI parameters) then the MPET will not have the current ramp down sequence.
  • Coasting: MPET routine completes the sequence by allowing the motor to coast by enabling Hi-Z. The motor back EMF and indicative values of mechanical parameters are measured during the motor coasting period. If the motor back EMF is lower than the threshold defined in STAT_DETECT_THR, the MPET_BEMF_FAULT is generated.

Selecting the parameters from EEPROM or MPET

The MPET estimated values are available in the MTR_PARAMS Register. Setting the MPET_WRITE_SHADOW bit to 1, writes the MPET estimated values to the shadow registers and the user-configured (from EEPROM) values in MOTOR_RES, MOTOR_IND, MOTOR_BEMF_CONST, CURR_LOOP_KP, CURR_LOOP_KI, SPD_LOOP_KP and SPD_LOOP_KI shadow registers will be overwritten by the estimated values from MPET. If any of the shadow registers are initialized to zero (from EEPROM registers), the MPET estimated values are used for those registers independent of the MPET_WRITE_SHADOW setting. The MPET calculates the current loop KP and KI by using the measured resistance and inductance. The MPET does an estimation of the mechanical parameters including the inertia and frictional coefficient at the shaft (includes both motor and shaft coupled load). These values are used to set an initial values speed loop KP and KI. The estimated speed loop KP and KI setting can be used as an initial setting only and TI recommends to tune these parameters on application by the user based on the performance requirement.

Note: Set VDC_FILT_DIS to 1b before running MPET.