DC-DC Power Supply Design for the Computing Industry Presented by Ronil Patel 12/03/03 EE 136 - Power Electronics SJSU © 2003.

DC-DC Power Supply DC-DC Power Supply DesignDesign

for the Computing for the Computing IndustryIndustry

Presented byPresented by

Ronil PatelRonil Patel

12/03/0312/03/03

EE 136 - Power ElectronicsEE 136 - Power Electronics

SJSUSJSU

© 2003© 2003

AgendaAgenda

Design for?Design for? Topologies usedTopologies used A typical design cycleA typical design cycle

RequirementsRequirements Design processDesign process

Challenges common to the IndustryChallenges common to the Industry

The Market segmentThe Market segment

Computing

Telecomm

Other

Automotive

Computing SegmentComputing Segment

Desktop Enterprise Portable Hand-held

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Reference: Apple Computer

Commonly Used Commonly Used TopologiesTopologies

Buck ConvertersBuck Converters Boost ConvertersBoost Converters Linear RegulatorsLinear Regulators

<150mW - Portable designs<150mW - Portable designs 3W - Desktop designs3W - Desktop designs

Typical Notebook Typical Notebook PlatformPlatform

AC

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Battery Charger

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5V / System Rail

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LCD / Inverter

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Reference: Apple Computer

A product design cycleA product design cycle

Requirements

Design

Demo BoardTesting

I

Production

III

Schematic Entry

PCB Layout

Fabrication

Testing Stages

II

Requirements - Requirements - PowerPower

Static RequirementsStatic Requirements Vout / IoutVout / Iout

Dynamic requirementsDynamic requirements Transient loads (di/dt)Transient loads (di/dt) Voltage tolerances (Transient droop)Voltage tolerances (Transient droop)

Requirements - ProductRequirements - Product

$$$ - Design cost$$$ - Design cost Available Real EstateAvailable Real Estate Efficiency targetEfficiency target Design Reliability targetDesign Reliability target

Lifetime (MTBF) - ServersLifetime (MTBF) - Servers Safety (Single-fault / Safety (Single-fault /

Current-limit) Current-limit) Hand-held productsHand-held products PortablesPortables

Project Time lineProject Time line

Topology selection

DesignDesign Design calculations/simulationsDesign calculations/simulations

Switching FrequencySwitching Frequency Inductance, Input/Output capacitanceInductance, Input/Output capacitance No. of Phases/FETsNo. of Phases/FETs Power losses - FET, Capacitor, InductorPower losses - FET, Capacitor, Inductor

Reference: International Rectifier

Design (cont’d)Design (cont’d) Reliability Reliability

De-rating / SOA curvesDe-rating / SOA curves

Monte Carlo (Worst-case) analysisMonte Carlo (Worst-case) analysis Errors/Tolerances over time and temp. Errors/Tolerances over time and temp. RSS (Root Sum Square)RSS (Root Sum Square)

Reference: International Rectifier

Component SelectionComponent Selection

CostCost Package size Package size (typically smaller, more $$)(typically smaller, more $$)

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Reference: Rubycon Corporation

Aluminum ElectrolyticsPolymer Tantalum

Component Selection Component Selection (cont’d)(cont’d)

PerformancePerformance Variation over timeVariation over time

Derating Derating Voltage (Caps, FETs)Voltage (Caps, FETs) RMS current (Caps)RMS current (Caps)

Component Selection Component Selection (cont’d)(cont’d)

Vendor selection Vendor selection All the previous factors All the previous factors (Cost & (Cost &

performance)performance) Reliability and quality of componentsReliability and quality of components Business ReputationBusiness Reputation

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QuickTime™ and aTIFF (Uncompressed) decompressor

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Where are we?Where are we?

Preliminary design and component Preliminary design and component selection complete.selection complete.

Schematic is ready --> Layout & Schematic is ready --> Layout & FabricationFabrication

Reference: Linear Technology

Layout GuidelinesLayout Guidelines

Impedances for high current pathsImpedances for high current paths V = L * di/dtV = L * di/dt V = R * IV = R * I

Cu area for power dissipationCu area for power dissipation Number of viasNumber of vias Short Gate drive tracesShort Gate drive traces Compact layout to minimize ground Compact layout to minimize ground

loopsloops

Development/TestingDevelopment/Testing

3 - 6 development stages3 - 6 development stagesSchematic Entry

PCB Layout

Fabrication

Testing Stages

ProductionProduction

Yield issuesYield issues

Field failuresField failures

Failure Analysis Design fixes

Is that it?Is that it?

A zillion design A zillion design challenges…challenges…

Number of voltage railsNumber of voltage rails Size - PortablesSize - Portables Cost - Desktop Cost - Desktop Efficiency / Thermal designsEfficiency / Thermal designs

The biggest challenge..The biggest challenge..

Processor voltage requirementProcessor voltage requirement Faster di/dtFaster di/dt Impedance between regulator and Impedance between regulator and

Processor core a growing concernProcessor core a growing concern DC regulation accuracy more DC regulation accuracy more

predominantpredominant

SummarySummary

Computing industryComputing industry Example of a typical platformExample of a typical platform The detailed design processThe detailed design process Some key challenges faced by the Some key challenges faced by the

industryindustry

Questions / Comments ?