Monolithic Power Systems, Inc. · NASDAQ:MPWR

Monolithic Power Systems — Technical Presentation (May 2020)

22 slides from Monolithic Power Systems's technical presentation, May 2020

1. Slide 1: Motor Driver ICs: Power Dissipation and PCB Layout

   Motor Driver ICs Power Dissipation and PCB Layout Pete Millett Senior Technical Marketing Engineer May 2020

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: Motor Drivers – Power Dissipation and PCB Design

   Motor Drivers – Power Dissipation and PCB Design Introduction to Motor Driver ICs Power Dissipation in Drivers PCB Design for Power Dissipation Summary / Q&A

4. Slide 4: An Introduction to Motor Driver ICs

   An Introduction to Motor Driver ICs Brushed DC Motor Brushless DC Motor Stepper Motor

5. Slide 5: Inside a DC Motor Driver IC

   Inside a DC Motor Driver IC Internal Power Power FETs VIN UVLO VIN OTS Charge nFAULT Pump IN1 OUT1 EN1 Control Logic Gate IN2 Drivers EN2 OUT2 µC Curr. Limit CM1 CM2 GND SR REF Gate Logic Drivers

6. Slide 6: 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 tR tF Total Power P = PR + PS + PQ

7. Slide 7: Power Dissipation in Stepper Motor Driver ICs

   Power Dissipation in Stepper Motor Driver ICs Internal VIN Power VIN MP6500 VCP Charge VIN IA CPA Pump VREF CPB UVLO VG Int. VCC OVP LS Gate OTS Drive V Power IB FETs Gate AOUT1 Driver 8 Segments nFAULT AOUT2 Half-Step STEP Curr. DIR Reg. ISENSE nENBL µC MS1 MS2 IA Control VIN nSLEEP Logic BOUT1 Gat

8. Slide 8: Brushless Motor Drivers

   Brushless Motor Drivers Gate Internal Drivers Power VIN Logic CP1 CP2 VCP VIN VG Power Charge Pump VCP LDO VG FETs nSLEEP ENA/LSA ENB/LSB Timing and SA ENC/LSC Control HS Gate SB Logic VCP Driver PWMA/HSA SC PWMB/HSB LS Gate PWMC/HSC VG Driver OC_REF LSS Fault OCP Comparator nFAULT Handling VIN SOC

9. Slide 9: Power Dissipation Example

   Power Dissipation Example Using the MP6550 IC as an example: Let’s assume you are driving a load with 5V, 2A output current with a PWM frequency of: • Using the RDS(ON), we will dissipate (5A)2 x 0.1Ω = 0.25W in the high side, and (5A)2 x 0.1Ω = 0.25W in the low side • Static power will be 5V x 1.2m

10. Slide 10: A Problem: RDS(ON) vs. Temperature

    A Problem: RDS(ON) vs. Temperature

11. Slide 11: Peak vs. Average and RMS Load Current

    Peak vs. Average and RMS Load Current DC Motor Start-Up Current Stepper Motor RMS Current 3.6A Peak for ~20ms 2A peak ≈ 1.4A RMS

12. Slide 12: Thermal Resistance & Models

    Thermal Resistance & Models Simple Estimation: Die temperature = ambient temp + (P x ΘJA)

13. Slide 13: Temperature Rise Example

    Temperature Rise Example Using the MP6550 IC as an example: Total power dissipation is 560mW: • Temperature rise is P x ΘJA, so 0.56 x 80 = 44.8°C • Junction temperature is TA + TR. If we assume room temperature of 25°C, then the junction is at 25 + 44.8 = 69.8°C. If the ambient is 70°C, then the ju

14. Slide 14: Temperature Rise vs. Output Current

    Temperature Rise vs. Output Current Bigger Package = Better Thermals Temp Rise MP6600 QFN Temp Rise MP6500 TSSOP 120 120 100 100 80 80 60 60 Temp Rise Temp Rise 40 40 20 20 0 0 0 0.5 1 1.5 2 2.5 0 0.5 1 1.5 2 2.5 3

15. Slide 15: PCB Design for Power Dissipation

    PCB Design for Power Dissipation

16. Slide 16: Effect of Layer Count & Planes

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

17. Slide 17: Exposed Pads on TSSOP & QFN

    Exposed Pads on TSSOP & QFN O000000 OO000000 |~ o000000 |0 ¢ mrS

18. Slide 18: Flip-Chip QFN and LGA Packages

    Flip-Chip QFN and LGA Packages Mold Compound Die Leadframe Bump(Copper) Bump(Solder) Lead Finish

19. Slide 19: Thermal Vias

    Thermal Vias Traces 1oz Copper Pad Traces FR-4 1.6mm Copper Hole Plating 1oz Copper Plane 0.3mm Finished Via 1mm Finished Via 218ºC/W 49ºC/W Solid Connection Thermal Relief YES! NO!

20. Slide 20: What Happens if the Exposed Pad isn't Soldered?

    What Happens if the Exposed Pad isn’t Soldered? MP6500 Driving 2A Peak Stepper Motor 4-Layer PCB Exposed Pad Soldered Exposed Pad Not Soldered

21. Slide 21: Summary

    Summary • Calculate the power dissipated in your motor driver IC • Or work backwards and calculate maximum current from thermal conditions • Minimize thermal resistance • Bigger is always better • Multi-layer boards work best • Use thermal vias to spread heat • ALWAYS solder the exposed pad

22. Slide 22: 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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