Monolithic Power Systems, Inc. · NASDAQ:MPWR

Monolithic Power Systems — Technical Presentation (March 2021)

21 slides from Monolithic Power Systems's technical presentation, Mar 23, 2021

  1. Slide 1: Motor Driver ICs: Faults and Protection

    Motor Driver ICs Faults and Protection Pete Millett Senior Technical Marketing Engineer March 2021

  2. Slide 2: Pete Millett – Senior Technical Marketing Engineer

    Pete Millett – Senior Technical Marketing Engineer 2014–Present • MPS Senior Technical Marketing Engineer for motor driver ICs • Responsible for new product definitions as well as application engineering 2005–2013 • Systems Engineer and Systems Manager at Texas Instruments • Product definition and s

  3. Slide 3: Agenda

    Motor Drivers – Power Dissipation and PCB Design DC Motor Basics Starting, Stopping, and Reversing Motors Abnormal Stresses – Shorts, Overvoltage Motor Driver Protection Features Summary / Q&A

  4. Slide 4: DC Motor Basics

    DC Motor Basics Series Resistance RS Power Source VSRC Back EMF VBEMF

  5. Slide 5: Torque and Current

    Torque and Current mrS

  6. Slide 6: DC Motor Specs and Ratings

    DC Motor Specs and Ratings Output Power 15 Watts Nominal Voltage (VSRC) 24 Volts No Load Speed 4000 RPM No Load Current 0.11 Amps Full Load Speed 2920 RPM Full Load Continuous Torque 50 mNm Full Load Continuous Current 1 A Stall Torque 190 nMn Stall Current 3.6 Amps Resistance (RS) 6.7 Ω

  7. Slide 7: Startup of a DC Motor

    Startup of a DC Motor Electrical energy Kinetic energy Series Resistance RS Current Power Source VSRC Rotation Torque Back EMF 0V When speed = 0: I = VSRC / RS

  8. Slide 8: Managing Startup Current

    Managing Startup Current 3.6A 1A 60mS 120mS

  9. Slide 9: Stopping the Motor: Coasting

    Stopping the Motor: Coasting Kinetic energy Series Resistance RS Rotation Torque Back EMF VBEMF Heat Coast I=0

  10. Slide 10: Stopping the Motor: Braking

    Stopping the Motor: Braking Electrical energy Kinetic energy Series Resistance Heat RS Rotation Torque Current Back EMF VBEMF Heat Short Brake I = VSRC / RS

  11. Slide 11: Reversing the Motor

    Reversing the Motor Electrical energy Kinetic energy Series Resistance RS Current Power Source VSRC Back EMF VBEMF Reverse I = (VBEMF + VSRC) / RS = ~ 2 * VSRC / RS

  12. Slide 12: Short Circuits

    Short Circuits Fault Signal Output Voltage 38A! Output Current

  13. Slide 13: Voltage Stresses

    Voltage Stresses Current Driver

  14. Slide 14: Voltage Rise due to Deceleration

    Voltage Rise due to Deceleration Electrical energy Kinetic energy Voltage! Current Current Rotation Torque H-Bridge

  15. Slide 15: Thermal Stresses

    Thermal Stresses Resistive Losses PR = I2R VIN

  16. Slide 16: Motor Driver Protection Features: Overcurrent / Short Circuit

    Motor Driver Protection Features: Overcurrent / Short Circuit VIN HS Gate Timing and VCP Driver Control OUT1 Logic LS Gate OUT2 VG Driver `` OC_REF OCP Comparator VIN Fault nFAULT Handling UVLO_REF UVLO Comparator OVP_REF TSD VIN OVP Comparator

  17. Slide 17: False Overcurrent Trips

    False Overcurrent Trips VIN VIN OUT1 OUT2 GND

  18. Slide 18: Motor Driver Protection Features: Over/Under Voltage

    Motor Driver Protection Features: Over/Under Voltage VIN HS Gate Timing and VCP Driver Control OUT1 Logic LS Gate OUT2 VG Driver `` OC_REF OCP Comparator VIN Fault nFAULT Handling UVLO_REF UVLO Comparator OVP_REF TSD VIN OVP Comparator

  19. Slide 19: Motor Driver Protection Features: Thermal Protection

    Motor Driver Protection Features: Thermal Protection VIN HS Gate Timing and VCP Driver Control OUT1 Logic LS Gate OUT2 VG Driver `` OC_REF OCP Comparator VIN Fault nFAULT Handling UVLO_REF UVLO Comparator OVP_REF TSD VIN OVP Comparator

  20. Slide 20: Summary

    Summary • Consider the stresses in a motor drive circuit when starting, stopping, and reversing the motor • Minimize power supply inductance • Add clamp circuits and large bulk capacitors to mitigate voltage transients • Be aware of heat dissipated in a motor driver, especially during abnormal condi

  21. Slide 21: Q&A

    Q&A Please submit questions through the “Q&A” menu option in the Zoom app This webinar and others will be available for on-demand streaming at: MonolithicPower.com/webinars

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