Monolithic Power Systems, Inc. · NASDAQ:MPWR

Monolithic Power Systems — Technical Presentation (September 2023)

31 slides from Monolithic Power Systems's technical presentation, September 2023

1. Slide 1: Choosing the Right Stepper Motor Driver

   Choosing the Right Stepper Motor Driver Pete Millett Staff Technical Marketing Engineer September 2023

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

   Pete Millett – Staff Technical Marketing Engineer 2014–Present • MPS Staff 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 sys

3. Slide 3: Stepper Motor Basics – Operational Review

   Stepper Motor Back EMF Stepper Motor Basics – Operational Review Stepper Motor Driver Datasheet Specs Finding the Right Stepper Motor Driver Summary / Q&A

4. Slide 4: Stepper Motor Basics

   Stepper Motor Basics mrs

5. Slide 5: Stepper Motor Construction

   Stepper Motor Construction Images from www.allaboutcircuits.com Permanent Magnet Stepper Motor Hybrid Stepper Motor

6. Slide 6: Driving a Stepper Motor

   Driving a Stepper Motor VSUPPLY ao . Qf ae my iz la ———<—n) Ai}—_{ & ga fal 4 came lone 7 1 mmm fagaa! Phase A 2 s _ Q2 Winding 1 | al [96 Winding 2 ooh 3 é © | [B1 4 = = rt B2|| & < i 7 N a ta BG y N a € o +P 5 3 8 é — e 2 Stator ASF 1 C1 = c2 Stator B D1 D2 Phase B mrs

7. Slide 7: Step Modes and Microstepping

   Step Modes and Microstepping Full Step Half-Step +70.7% IA -70.7% +70.7% IB -70.7% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Non-Circular Half-Step (1-2 Phase) Quarter-Step

8. Slide 8: Stepper Motor Driver ICs

   Stepper Motor Driver ICs mrs

9. Slide 9: Stepper Driver ICs: What’s Inside (Simple)

   Stepper Driver ICs: What’s Inside (Simple) Gate Drivers VIN VIN MP6500 VCP VIN Internal Charge Pump CPA Power VG VREF Int. VCC UVLO CPB OVP LS Gate OTS Drive V Gate AOUT1 Driver nFAULT AOUT2 STEP Curr. DIR nENBL Reg. ISENSE Power µC MS1 MS2 FETs Control VIN nSLEEP Logic BOUT1 Gate Driver Motor ROSC

10. Slide 10: Stepper Driver ICs: What’s Inside (Advanced)

    Stepper Driver ICs: What’s Inside (Advanced) VIN VIN MP6602 VCP VIN Gate VCC Drive Reg VCC Internal Supplies VG GND & Ref. AOUT1 Gate nFAULT Driver AOUT2 nRESET STEP PGND DIR ENBL Curr. ISENSE SLEEP Reg. µC nSCS Stall SCLK SPI Det. SDATI I/F VIN SDATO Control BOUT1 Logic SPI OSC Gate Driver BOUT2 Mo

11. Slide 11: Stepper Driver ICs: Basic Features

    Stepper Driver ICs: Basic Features MP6500 CPA 100nF nFAULT CPB STEP VCP VIN DIR 1uF VIN µC nENBL MS1 VG 220 MS2 nF nSLEEP AOUT1 AOUT2 ISET BOUT1 ROSC Step BOUT2 Motor GND

12. Slide 12: Voltage and Current Ratings

    Voltage and Current Ratings This is the input power supply voltage range that drives the motor. This current rating is the amount of current that the driver is capable of driving into the windings. It can be very misleading! This is the internal resistance of the MOSFETs in the H-bridge. It is usual

13. Slide 13: Driver Features

    Driver Features Older stepper motor drivers use an external shunt to regulate current. Different drivers support different step modes or degrees of microstepping. https://www.monolithicpower.com/en/why-microstepping-isnt-as-good-as-you-think Accurate current control requires consideration of current

14. Slide 14: Stepper Driver Current Ratings

    Stepper Driver Current Ratings Maximum Current Highest permitted instantaneous current before OCP Peak -or- highest normal winding current Maximum Highest normal winding current Highest continuous winding current Continuous -or- highest normal winding current Average Highest average winding current

15. Slide 15: Power Dissipation

    Power Dissipation mrs

16. Slide 16: RDS(ON) Specifications

    RDS(ON) Specifications VIN RDS(ON) HS #1 RDS(ON) HS #2 MP6500: Total Effective Resistance = ~353mΩ RDS(ON) LS #1 RDS(ON) LS #2 Competitor: Total Effective Resistance = ~900mΩ

17. Slide 17: A Problem: RDS(ON) vs. Temperature

    A Problem: RDS(ON) vs. Temperature RDS(ON) vs. Temperature

18. Slide 18: Power Dissipation in Motor Drivers

    Power Dissipation in Motor Drivers Resistive Losses Switching Losses Static Losses PR = I2R PS ≈ ½ x V x I x fsw x tR PQ = VIN x IQ + ½ x V x I x fsw x tF VIN 2 IR I2R I2R I2R tR tF Total Power P = PR + PS + PQ

19. Slide 19: MP6500 Total Power Dissipation Calculation

    MP6500 Total Power Dissipation Calculation Resistive Losses: PR = 1.41A2 x 353mΩ = 705mW per H-bridge Switching Losses: Estimated PSW = ~70mW per H-bridge Static Losses: PQ = 24V x 1.5mA = 36mW Total Power: 2 x 755mW + 2 x 70mW + 36mW = 1.58W

20. Slide 20: Thermal Resistance & Models

    Thermal Resistance & Models Simple Estimation: Die Temperature = Ambient Temperature + (P x ΘJA)

21. Slide 21: PCB Design for Power Dissipation

    PCB Design for Power Dissipation

22. Slide 22: Effect of Layer Count & Planes

    Effect of Layer Count & Planes MP6500 Driving a 2A Peak Stepper Motor 2 Layers 4 Layers (2 Planes)

23. Slide 23: Current Ratings Revisited

    Current Ratings Revisited mrs

24. Slide 24: Datasheet Current Ratings Are Almost Meaningless!

    Datasheet Current Ratings Are Almost Meaningless! MP6500 – Current rating is “2.5A maximum” Effective RDS(ON) is 380mΩ Competitor – Current rating is “2.4A peak, 1.5A full scale” Effective RDS(ON) is 900mΩ

25. Slide 25: Competitor Total Power Dissipation Calculation

    Competitor Total Power Dissipation Calculation Resistive Losses: PR = 1.41A2 x 900mΩ = 1.79W Switching Losses: Estimated PSW = ~70mW Static Losses: PQ = 24V x 5mA = 120mW Total Power: 2 x 1.79W + 2 x 70mW + 120mW = 3.83W

26. Slide 26: Temperature Rise

    Temperature Rise MP6500 (TSSOP) – 1.58W x 32°C/W = 51°C temperature rise TJ = 150°C when TA = 99°C Competitor (TSSOP) – 3.83W x 30.9°C/W = 118°C temperature rise TJ = 150°C when TA = 32°C

27. Slide 27: How Much Current Can These Parts Really Drive?

    How Much Current Can These Parts Really Drive? At Room Temperature (25°C): MP6500 (TSSOP) – Max Power = (150° - 25°) / 32°C/W = 3.9W Maximum Current per Winding = 2.3A RMS (3.2A peak) Competitor (TSSOP) – Max Power = (150° - 25°) / 30.9°C/W = 4W Maximum Current per Winding = 1.4A RMS (2A peak) At Hi

28. Slide 28: …And It May Be Even Worse!

    ...And It May Be Even Worse! mrs

29. Slide 29: Datasheet Specifications

    Datasheet Specifications Image from www.dilbert.com

30. Slide 30: Summary

    Summary • Don’t take all the information on a stepper driver datasheet at face value! (Not even mine!) • Do your own calculations when it comes to the current rating needed • Take into account PCB construction and ambient temperature

31. Slide 31: 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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