Monolithic Power Systems, Inc. · NASDAQ:MPWR
Monolithic Power Systems — Technical Presentation (March 2023)
21 slides from Monolithic Power Systems's technical presentation, March 2023
Slide 1: Motor Drivers: Thermal Management
Motor Drivers: Thermal Management Christophe Vaucourt – Sr. Technical Marketing Engineer Yunping Lang – Motor & Audio Application Engineering Manager Tommy (Qi) Tang – Thermal Modeling Engineer
Slide 2: Thermal Resistance and Electrical Analogy
Thermal Resistance and Electrical Analogy Thermal resistance is a heat property and a measurement of a temperature difference by which material resists a heatflow 1. The contents of this table are from Technische Temperaturmessung: Volume I, Frank Bernhard, ISBN 978-3-642-62344-8. 2. el refers to el
Slide 3: Thermal Theory
Thermal Theory Heat Transfer Paths Conduction Heat transfer mechanisms: Convection 𝑘 ∙ 𝐴 ∙ ∆𝑇 • Conduction: 𝑄 = Die 𝐿 EP Radiation • Convection: 𝑄 = 𝑘 ∙ 𝐴 ∙ ∆𝑇 PCB • Radiation: 𝑄 = ε ∙ 𝜎 ∙ 𝐴 ∙ (𝑇𝑃𝐶𝐵 4 − 𝑇𝐴𝑀𝐵 4 ) Where: 𝑄 = ℎ𝑒𝑎𝑡 ℎ = 𝑐𝑜𝑛𝑣𝑒𝑐𝑡𝑖𝑜𝑛 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡…
Slide 4: Thermal Resistance Definitions
Thermal Resistance Definitions (1) RθJA junction-to-ambient thermal resistance: (2) RθJB junction-to-board thermal resistance: RθJA = (TJ – TA) / PH RθJB = (TJ – TB) / PHB Where RθJA = thermal resistance from junction-to-ambient (°C/W) Where RθJB = thermal resistance from junction-to-board (°C/W) TJ
Slide 5: JESD51 Test Setup (RθJA, ΨJT, ΨJB)
JESD51 Test Setup (RθJA, JT, JB) RθJA, JT, and JB thermal resistances are based on The PCB board (high-K) has 4 metal layers, 1.6mm JESD51-2 (Integrated Circuits Thermal Test Method thickness. Environment Conditions - Natural Convection (Still Air)). The device is attached to the PCB and placed
Slide 6: PSI Junction-Top (ΨJT) vs. Theta Junction-Case (θJC)
PSI Junction-Top (ΨJT) vs. Theta Junction-Case (JC) Power Cu plate to Package Top 25°C constant temp. Power to Package Lead PD Die Die EP EP Power into PCB PCB PCB TC(TOP) TC(TOP) TJ TC(BOT) TPCB TA TJ TPCB TA Ambient temp. Ambient temp. PD PD 𝑇𝐽 − 𝑇𝐶(𝑇𝑂𝑃) 𝑇𝐽 − 𝑇𝐶(𝑇𝑂𝑃) Ψ𝐽𝑇 = 𝜃𝐽𝐶…
Slide 7: PSI Junction-Board (ΨJB) vs. Theta Junction-Board (θJB)
PSI Junction-Board (ΨJB) vs. Theta Junction-Board (JB) Cool plate Power to Package Top Power to Package Lead Coolant in Coolant out Die Die EP PD Power into PCB PCB PCB TC(TOP) Lead thermocouple TJ TC(BOT) TPCB TA TJ TC(BOT) TPCB TA Ambient temp. Ambient temp. PD PD 𝑇𝐽 − 𝑇𝑃𝐶𝐵 𝑇𝐽 − 𝑇𝑃𝐶𝐵…
Slide 8: MPQ6612 Simulated Thermal Parameters
MPQ6612 Simulated Thermal Parameters Theta JA (Junction-to-Air) Theta JC_TOP (Junction-to-Case Top) RθJA = (TJ – TA) / PH RθJC_TOP = (TJ – TC) / PH TJ = 91.5°C, TA = 25.1°C TJ = 56.2°C, TC_TOP = RθJA = 44.3°C/W 0°C RθJC_TOP = 37.5°C/W Theta JB (Junction-to-Coard) Theta JC_BOT (Junction-to-Case Botto
Slide 9: How To Use Thermal Resistance Parameters
How To Use Thermal Resistance Parameters • JA: Thermal resistance of the entire system from the die • ΨJB: Characteristic thermal resistance allowing system to the ambient air. It is a measure of the device’s ability designers to calculate the device’s junction temperature to dissipate heat into th
Slide 10: Pulsed Operation
Pulsed Operation When a motor driver is subjected to a pulsed load, higher peak power dissipation must be tolerable. The materials in power packages have a definite thermal capacity; thus the critical junction temperature is not reached instantaneously, even when excessive power is being dissipated
Slide 11: First Order Transient Thermal Model
First Order Transient Thermal Model (SI) (PKG) (PCB) TJ TPCB TA Ambient temp. PD CTH (SI) CTH (PKG) CTH (PCB) Package specific Not part of the package The first cell represents the thermal characteristics of the silicon itself, and is characterized by the small volume with a correspondingly low t
Slide 12: Thermally Enhanced PCB: Basic Rules
Thermally Enhanced PCB: Basic Rules • Copper is nearly perfect in perpendicular direction — thickness is irrelevant! • It is more efficient to conduct heat through the plane rather than along its length. • Thicker copper layers improve the heat transfer along the PCB. • FR4 is a poor conductor along
Slide 13: MPQ6612: 4-Layer Evaluation Board
MPQ6612: 4-Layer Evaluation Board PCB Characteristics: OUT2 - 4-layer board (63.5mmx63.5mm) GND OUT1 - 70µm copper on all layers - 1.6mm total thickness VIN GND GND Top Layer Mid-Layer 1 VIN OUT2 OUT1 VIN GND GND Mid-Layer 2 Bottom Layer
Slide 14: Monitoring IC Junction Temperature
Monitoring IC Junction Temperature Temp. sense VIN VPOSBIAS VHSD OFF VHSD HSD HSD PWMHS1 PWMHS2 One method to measure the temperature of the power FETs is PWMHS2 1.5mA Gate Driver Control to employ the junction itself as a temperature sensor, since OUT1 there is a strong correlation between the forw
Slide 15: Monitoring IC Junction Temperature (contd.)
Monitoring IC Junction Temperature (contd.) IN1 pad IN1 pad IN1 pad Output 1 (3.3W, t = 10s) Output 1 (3.3W, t = 60s) Output 1 (3.3W, t = 1000s) Input Logic Input Buffer Port Temperature gradient across the power stage (ca. 2000µm): ca. 30°C Temperature gradient power stage to I/O pad: ca. 10°C 100µ
Slide 16: Characteristic Thermal Impedance
Characteristic Thermal Impedance The transient thermal impedance is measured using the same MOSFET body diode for heating and monitoring the temperature. A pulsed current (ISENSE, IDRIVE) is applied to the device. The change in the diode’s forward voltage is monitored before and after the pulse…
Slide 17: High-Side Diode Output 1 Power Dissipation (EVQ6612A-L-00A)
High-Side Diode Output 1 Power Dissipation (EVQ6612A-L-00A) Single-Pulse (20s) Thermal Response (Heating, Cooling) Large thermal gradient over the chip area The junction temperature can be estimated accurately based on a package case temperature measurements Thermal steady state is reached after sev
Slide 18: High-Side Diode Output 1+2 Power Dissipation (EVQ6612A-L-00A)
High-Side Diode Output 1+2 Power Dissipation (EVQ6612A-L-00A) Single-Pulse (10s) Thermal Response (Heating, Cooling) The IC’s thermal performance is significantly better on an application board vs. a JEDEC board
Slide 19: Conclusion
Conclusion Maximize PCB Thermal Performance • Consider using thick copper for high power designs • Use multiple layers for ICs in small packages • Make the PCB as thin as possible by reducing FR4 thickness • Optimize top layer power trace design • Use vias in power lines, placed as close as possible
Slide 20: Complementary Material
COMPLEMENTARY MATERIAL mMmPS
Slide 21: How to Generate Power Dissipation
How to Generate Power Dissipation VIN nSLEEP VHSD VHSD IN1 HSD HSD IN2 PWMHS1 PWMHS2 PWMHS2 Gate Driver Control OUT1 Parasitic BJT OUT2 PWMLS2 Current limited voltage source VLSD VLSD VF (ILIM) LSD LSD PWMLS1 PWMLS2 GND
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