WEBENCH® Power Designer & Power Architect Basics

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Walkthrough of WEBENCH Power Designer

Electrical and Thermal Simulation

Build it and Reporting

Objectives

WEBENCH Overview

WEBENCH Tools

Power Designer Power supply and system architect design

LED driver design

Sensor analog front end design

Filter design and simulation

PLL implementation

LED Designer

Sensor Designer

Active Filter Designer

PLL Designer

Op amp design and simulationAmplifier Designer

WEBENCH Supports Broad Portfolio 12 Years Of Modeling And Verification

• LM258x

• LM259x

• LM267x

• LM557x, LM2557x

• LM2267x, LM22680

• LM315x

• LMZ1050x

• LMZ1420x/200x

• LM201xx/3x3

• LM(2)5005/07/10/(11)

• LM5001/02/08/09

• LM(2)5085/88

• LM2734/35/36

• LM2743

• LM2830/31/32

• LM2852/53/54

• LM3100/02/03

• LM3478/88

• LM34910/17/19/30

• LM3668

• LM3670/71/73/74

Circuit Calc & Sim model CC but no Sim WebTHERM /Build It

• LM2700

• LM2622

• LM3481

• LM3224

• LM258x

• LM259x

• LM267x

• LM557x, LM2557x

• LM2267x, LM22680

• LM315x

• LM5118

Switchers/Controllers/LED Drivers: 162 base part numbers in WEBENCH

Supported Topologies: Buck (over 60% of total designs), Boost, Flyback and SEPIC (newest)

• 1.0V: LM2743

• 2.5V: LM3670/1

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• 40A-60A: LM(2)5119, LMZ22010 (interleaved)

• 30A: LM27402

• 20A: LM2743, LM5116

• 0.6V: LM283x, LM2743, LM3150, etc.

• 100V: LM5116

• 95V: LM5008/9Vin Max

Vin Min

Coverage of WEBENCH Enabled Parts (Buck Switchers)

Vout Min

Iout

Multilingual capability

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• Chinese• simplified• traditional

• Japanese• Korean• Russian• Portuguese• German (coming soon)

Distributor & vendor versions

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And more…

• >110 component manufacturers & distributors• >21,000 components• Price and availability electronically updated hourly

• Avago exampleAvago example• Only contains Avago LEDsOnly contains Avago LEDs

WEBENCH® Tool Suite

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WEBENCH Power Designer

WEBENCH Visualizer

FPGA/Power Architect

AlteraPowerPlay

Power Architect & FPGAs

From optimized design to prototype

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2. Create design

Custom prototypeovernight

Custom prototypeovernight

PrototypePrototype

4. Build It!

Generate schematic& electrical analysis

Generate schematic& electrical analysis

Generate layout &thermal analysis

Generate layout &thermal analysis

3. Analyze design

Select designSelect design

Enter requirementsEnter requirements

1. Enter reqs

Optimize for:Optimize for:

Use graphs to visualize design

Use graphs to visualize design

• Footprint• Efficiency

• Footprint• Efficiency

Access WEBENCH tools from homepage or product folder

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WEBENCH Visualizer:Calculates 50 Designs in 2 Seconds

ChartsCharts Recommended SolutionsRecommended Solutions

WEBENCH Dashboard

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Power Power TopologyTopology

BOMBOM

Optimization Optimization GraphsGraphsChartsCharts

OptimizerOptimizer

Share DesignShare Design

System System SummarySummary

SystemSystemOp ValuesOp Values

PrototypingPrototyping& Reports& Reports

CircuitsCircuits

DesignDesignReqsReqs

WEBENCH® Tool Suite

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WEBENCH Power Designer

WEBENCH Visualizer

Power Architect & FPGAs

WEBENCH Optimization Tuning

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WEBENCH Design Optimization

Optimization Setting

FrequencyComponent

SelectionSummary

1 – Smallest footprint Highest

• Smallest footprint• Don’t care about cost

Smallest size but lowest efficiency

2 – Lowest cost High • Lowest costHigh frequency means

smaller / cheaper components

3 – Balanced Medium• In stock• Low cost

Balanced approach using IC’s middle frequency

4 – High efficiency Low

• Low DCR, ESR, Vf• Low cost

Higher efficiency, with low cost but larger parts

5 – Highest efficiency Lowest

• Low DCR, ESR, Vf• Don’t care about cost

Highest efficiency but largest parts

Key Optimization Parameters Graphed

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Power DissipationBy Component

FrequencyIC Temperature

FootprintEfficiency BOM Cost

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Schematic – Buck Converter

Input Load

Current Path with Switch On

Current Path with Switch Off

Components: Input Capacitor Regulator with integrated FET Inductor Catch Diode Output Capacitor Feedback Network Feature Controls

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Visualize Behavior – Power Dissipation

Diode:Isw*Vf *(1-DutyC)

Inductor:ILRMS

2 * DCRCin:ICinRMS

2 * ESR

Cout:ICoutRMS

2 * ESR

Switch: DC: IswRMS

2 * Rsw * DutyC AC: ½ * Vin * Isw * (Trise + Tfall)/TswQuiescent: Iq * Vin

Efficiency = Pout / PinPin = Vout * Iout + Pdiss

FET Selection: AC Loss

• PswAC = ½ * Vdsoff * Idson * (trise + tfall)/Tsw

Vsw = -VdsIsw

TriseTfall

Regions of power loss (V*I)

Vg

Vth

Miller Plateau

Vth

Miller Plateau

Vdriver

Vsw

Switch Off On Off

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FET Selection: AC Loss

• PswAC = ½ * Vdsoff * Idson * (trise + tfall)/Tsw

Vsw = -VdsIsw

Trise Tfall

Regions of power loss (V*I)

Vg

Vth

Miller Plateau

Vth

Miller Plateau

Vdriver

Vsw

Switch Off On Off

Low Freq = Low LossHigh Freq = High Loss

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How To Reduce FET Power Loss

• Choose a FET with low RdsOn

• Choose a FET with low capacitance

• Lower the switching frequency

BUT

• Lowering frequency affects the inductor selection

• We want to keep the inductor ripple current constant– Because this changes the peak switch current and the Vout ripple

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Inductor Current vs Switch Voltage

Inductor Current

Switch Voltage

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Inductor Ripple Current

Voltage applied

Inductor Ripple Current (also determines peak switch current and Vout ripple)

dI = (1/L)*V*dt

OnTime

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Inductor Selection – Lower Frequency

Voltage applied

Inductor Ripple Current (also determines peak switch current and Vout ripple)

Lower Frequency =Increased On Time = Increased Inductor Ripple Current = Increased Peak Switch Current and Increased Vout Ripple

Higher frequency:

If L is kept constant, ILpp increases

Lower frequency:

dI = (1/L)*V*dt

OnTime

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Inductor Selection – Raise Inductance

Voltage applied

Inductor Ripple Current (also determines peak switch current and Vout ripple)

Higher frequency:

If L is kept constant, ILpp increases

Lower frequency:

dI = (1/L)*V*dt

OnTime

So we need to increase L

Lower frequency with higher inductance:

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Effect Of Lower Frequency On Inductor

• If we keep the inductor ripple current constant by increasing the inductance:– The inductor gets larger (more turns)

– The inductor power dissipation goes up (longer wire)

Optimization – efficiency vs footprint

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Left SideHigher frequencySmaller footprint

Right SideLower frequencyLower resistance

small inductor large inductor

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Optimization Summary

• To get high efficiency– Decrease frequency to reduce AC losses– Choose components with low resistance

• To get small footprint– Increase frequency to reduce inductor size– Choose components with small footprint

• Cost

• These parameters are at odds with each other and need to be balanced for a designer’s needs

• Tools are available to visualize tradeoffs and make it easier to get to the best solution for your design requirements

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• Design has been configured for stable operation BUT

• May want to verify under dynamic conditions

• Improve line/load transient response

• Minimize output voltage ripple

• Modify control loop

• Interactive waveform viewer allows detailed analysis of results

Why Do Electrical Simulation?

Visualize Results

Try Solutions

Identify Problems

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Electrical Simulation

Specify simtype

Click start to initiate sim

• Bode Plot• Line Transient• Load Transient• Startup • Steady State

Esim page

Waveform viewer

Click to view waveforms

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Waveform Viewer

Click on a tile to add a waveform

Click and drag down and to the right to zoom in

Click and drag up and to the left to zoom out

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Evaluate Transient Response

• LM22680– Voltage mode pulse width modulation control scheme (PWM)

– Lower part count – SIMPLE SWITCHER®

• LM25576– Emulated current mode (ECM)

– Fast transient response

• Will evaluate:– How does ECM compare with PWM

– Vin: 14-22V, Vout: 3.3V, Iout: 2A

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Buck Schematics

LM22680 PWM

LM25576 ECM

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LM22680 vs LM25576Vout for Load Transient

LM22680

(Pulse Width Modulated)

LM25576

(Emulated Current Mode) has faster transient response recovery time

Load Transient: 0.2 – 2.0A

50 usec rise/fall time

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Overlay simulations

• Red: LM22680 (Pulse Width Modulated)

• Blue: LM25576 (Emulated Current Mode) has faster transient response recovery time

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© 2011 National Semiconductor Corporation.

• Co-heating of parts not accounted for with ThetaJA

• Change copper thickness, airflow, ambient temperature, voltage, current

• Color temperature plot across the board

• Adjustable scaling

Why Do Thermal Simulation?

Visualize Results

Try Solutions

Identify Problems

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Why Do Thermal Simulation?

• Identify and solve thermal issues– Co-heating of adjacent parts not taken into account with thetaJA

• Different ways to solve thermal problems:– Heat sink– Fan– Copper area/thickness

• Thermal simulation factors– Model Types:

• Physical geometry/materials modeled for regulator• Lumped cuboid models for passive components• Board modeled as a separate part, with traces modeled explicitly

– Simulation accuracy• 3D conduction• Radiation• Convection

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WebTHERM® – Board Layout

Thermal Sim Page

PC Board

Inputs:•Input voltage•Current•Top and bottom ambient temperature•Copper thickness•Airflow•Board orientation

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WebTHERM® Results

•View interactions between components

•Diode and IC both generate heat

•Effect of backside copper and vias

Top

Bottom

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LM3150 Controller

4oz copper thicknessLow side FET is 68C

.5oz copper thicknessLow side FET is 117C

Vin: 14-22VVout: 3.3VIout: 6A

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Order a Build It® kit

Build It PageBuild It Page

Order custom prototype kit:• Bare board and parts• Hourly pricing and inventory updates• Shipped overnight

WEBENCH Visualizer

optimized designsoptimized designs

Efficiency vs footprint vs BOM cost

mouseover detailmouseover detail

change axeschange axes

Why are solutions different?

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WEBENCH® Tool Suite

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WEBENCH Power Designer

WEBENCH Visualizer

Power Architect

Real system means many supplies

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Many Loads, Many Supplies

• Core Supply 1.25V @ 3.0A

• FPGA IO 3.3V @ 0.5A

• Vcca 3.3V @ 0.2A

• Flash 3.3V @ 2.0A

• SDRAM 1.8V @ 1.0A

• CCD 2.5V @ 0.2A

• PLL 1.25 @ 0.2A

• Motor Control 12V @ 2.0A

• Miscellaneous 3.3V @ 2.0A

9 Loads and 5 Voltages

WEBENCH® Processor Architect

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Includes TI processors!Includes TI processors!

Loads are pre-populatedLoads are pre-populated

Adding new/more loads

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WEBENCH optimized now for systems

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Analyze Performance, Cost, and Footprint for Selected Architecture

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Share design

Complete design report

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Your design• Inputs• Supplies• Schematics • BOMs• Local Languages

WEBENCH Power Designer

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Dynamic design optimization:Provides supply configuration/topology based on size, cost,

efficiency

WEBENCH Design Tools save you time

Other Features (Not discussed today): Visualizer, Power Architect, LED Designer, FPGA/uP

Architect

Thanks

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Appendix

LED Lighting Gadgets

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Phase (TRIAC) Dimmable LED Drivers

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LM3466 Multi-String LED Current Equalization

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