WEBENCH® Power Designer & Power Architect Basics

Objectives     WEBENCH Overview Walkthrough of WEBENCH Power Designer  Electrical and Thermal Simulation  Build it and Reporting  2 2

Active Filter Designer WEBENCH Tools Power Designer Power supply and system architect design LED Designer LED driver design Sensor Designer Sensor analog front end design Active Filter Designer Filter design and simulation PLL Designer PLL implementation Amplifier Designer Op amp design and simulation 3

WEBENCH Supports Broad Portfolio 12 Years Of Modeling And Verification Circuit Calc & Sim model CC but no Sim WebTHERM /Build It 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 LM258x LM259x LM267x LM557x, LM2557x LM2267x, LM22680 LM315x LM5118 LM2700 LM2622 LM3481 LM3224 LM258x LM259x LM267x LM557x, LM2557x LM2267x, LM22680 LM315x LMZ1050x LMZ1420x/200x Switchers/Controllers/LED Drivers: 162 base part numbers in WEBENCH Supported Topologies: Buck (over 60% of total designs), Boost, Flyback and SEPIC (newest) WEBENCH has been around for over 10 years and new parts are being added regularly. National 3.0 Conference [insert presenter’s name(s)] 4 [Insert name of course] June 2008

Coverage of WEBENCH Enabled Parts (Buck Switchers) Iout 40A-60A: LM(2)5119, LMZ22010 (interleaved) 30A: LM27402 20A: LM2743, LM5116 Vout Min 0.6V: LM283x, LM2743, LM3150, etc. Vin Max 100V: LM5116 95V: LM5008/9 Vin Min 1.0V: LM2743 2.5V: LM3670/1 Page 5

Multilingual capability Chinese simplified traditional Japanese Korean Russian Portuguese German (coming soon)

Distributor & vendor versions Avago example Only contains Avago LEDs The WEBENCH Designer Eco-System makes value-based comparisons possible. Comprised of more than 110 component manufacturers and electronic distributors, the Eco-System provides electrical and physical characteristics across more than 21,000 components with price and availability updated hourly over the internet. And more… >110 component manufacturers & distributors >21,000 components Price and availability electronically updated hourly

Power Architect & FPGAs WEBENCH® Tool Suite Altera PowerPlay Power Architect & FPGAs FPGA/Power Architect WEBENCH Visualizer WEBENCH Power Designer

From optimized design to prototype 1. Enter reqs 2. Create design 3. Analyze design 4. Build It! Enter requirements Custom prototype overnight Optimize for: Generate schematic & electrical analysis Footprint Efficiency The WEBENCH Design Environment is an end to end prototyping system with 4 simple steps: The user enters design parameters and WEBENCH presents appropriate solutions. After the user choose a part, the WEBENCH Design Environment creates a design and provides the user with optimization capability. The user can also use the WEBENCH Design Environment simulators to fine tune the design. Finally a custom prototype kit is available overnight for parts with the Build It feature. Use graphs to visualize design Select design Prototype Generate layout & thermal analysis

Access WEBENCH tools from homepage or product folder Different ways to access WEBENCH Designer. User enters the input voltage range, output voltage and load current. Then hit “Start Design” button

WEBENCH Visualizer: Calculates 50 Designs in 2 Seconds Charts Recommended Solutions For this design criteria, the WEBENCH Visualizer calculates 46 possible solutions and ranks them in recommended order. The results are presented in a table and also in a graph. The user can select which parameters to plot in the graph such as BOM Cost, Efficiency, and Footprint, among other things. The user can change the desired optimization by using the knob in the upper left corner. Optimization 1 corresponds to low footprint, optimization 3 goes for low BOM cost and optimization 5 emphasizes high efficiency. The user can also filter the results using slider controls and also using checkboxes for different features. 11

WEBENCH Dashboard Share Design System Summary Optimizer Optimization Graphs Charts Circuits The main design dashboard gives the user an overview of the design including: Graphs Schematic Optimization tuning Operating values BOM Reporting Prototyping & Reports Design Reqs System Op Values BOM Power Topology

Power Architect & FPGAs WEBENCH® Tool Suite Power Architect & FPGAs WEBENCH Visualizer WEBENCH Power Designer

WEBENCH Optimization Tuning By turning the WEBENCH optimization knob, the user can adjust the optimization weighting between efficiency, footprint, and BOM cost.

WEBENCH Design Optimization Optimization Setting Frequency Component Selection Summary 1 – Smallest footprint Highest Smallest footprint Don’t care about cost Smallest size but lowest efficiency 2 – Lowest cost High Lowest cost High 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 Higher efficiency, with low cost but larger parts 5 – Highest efficiency Lowest Highest efficiency but largest parts 15

Key Optimization Parameters Graphed 3 Frequency IC Temperature Footprint Efficiency BOM Cost Power Dissipation By Component

Schematic – Buck Converter Components: Input Capacitor Regulator with integrated FET Inductor Catch Diode Output Capacitor Feedback Network Feature Controls Current Path with Switch On Current Path with Switch Off Input Load This is a schematic of a buck asynchronous voltage regulator circuit. It shows the current path with the switch on and also with the switch off. From this we can determine the primary contributors to power dissipation in the circuit.

Visualize Behavior – Power Dissipation Efficiency = Pout / Pin Pin = Vout * Iout + Pdiss Diode: Isw*Vf *(1-DutyC) Cout: ICoutRMS2 * ESR Switch: DC: IswRMS2 * Rsw * DutyC AC: ½ * Vin * Isw * (Trise + Tfall)/Tsw Quiescent: Iq * Vin Efficiency includes the losses from all the components. The major contributors are the regulator/switch and the catch diode depending on the duty cycle. Low duty cycle designs have higher power dissipation in the diode and high duty cycle designs have higher power dissipation in the regulator. Graphs of power dissipation vs current help to visualize the losses Inductor: ILRMS2 * DCR Cin: ICinRMS2 * ESR

FET Selection: AC Loss PswAC = ½ * Vdsoff * Idson * (trise + tfall)/Tsw Regions of power loss (V*I) Vsw Miller Plateau Miller Plateau Vdriver Vth Vth The AC loss occurs during the transition between the switch being on and off. This diagram shows the behavior of the FET during the transition from off to on then from on to off. The highlighted areas show regions of AC power loss. Isw Vg Vsw = -Vds Switch Off On Off Tfall Trise 19

FET Selection: AC Loss PswAC = ½ * Vdsoff * Idson * (trise + tfall)/Tsw High Freq = High Loss Low Freq = Low Loss Regions of power loss (V*I) Vsw Miller Plateau Miller Plateau Vdriver The % of the switching period that is spent in the transition regions is greater for higher switching frequencies. Thus, higher switching frequency means greater AC switching loss as is shown in the diagram in the upper left. Lowering the switching frequency lowers the losses as is shown in the upper right. AN-1628 has more details on this (http://www.national.com/an/AN/AN-1628.pdf). Vth Vth Isw Vg Vsw = -Vds Switch Off On Off Trise Tfall

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

Inductor Current vs Switch Voltage Voltage is applied to the inductor at the switch node minus the voltage at the output. This cause the current to rise in the inductor. When the switch is turned off, the inductor current goes down.

Inductor Ripple Current On Time Voltage applied dI = (1/L)*V*dt Inductor Ripple Current (also determines peak switch current and Vout ripple) The peak inductor current (and peak switch current) is a function of the average output current and the inductor ripple current. The peak inductor current is: ILaverage + 1/2 ILpp (the inductor ripple current) The average inductor current is: For Buck: ILaverage = Iout For Boost: ILaverage = Iout/(1-DC) where DC = duty cycle DC = (Vout-Vin+Vdiode+ILavg*DCR)/(Vout - Vswitch + Vdiode) Higher DCR means higher duty cycle and higher average inductor current The inductor ripple current is determined by the basic inductor equation: V = L dI/dt di = V/L dt Peak to peak inductor current (inductor ripple current) = Voltage applied across the inductor/L * time during which voltage is applied to the inductor. When the switch is closed we have: For Buck: ILpp = (Vin - Vswitchingloss - ILavg*DCR - Vout)/L * Ton For Boost: ILpp = (Vin - Vswitchingloss - ILavg*DCR)/L * Ton Since the on time is: Ton = duty cycle/switching frequency We see that the on time is inversely proportional to the switching frequency. So the lower the switching frequency, the higher the inductor ripple current and thus peak inductor current.

Inductor Selection – Lower Frequency Time Higher frequency: Voltage applied dI = (1/L)*V*dt Inductor Ripple Current (also determines peak switch current and Vout ripple) Lower frequency: Lower Frequency = Increased On Time = Increased Inductor Ripple Current = Increased Peak Switch Current and Increased Vout Ripple Lower frequency = longer ON time means more inductor ripple current and higher peak current and Vout ripple for a given inductance. If L is kept constant, ILpp increases

Inductor Selection – Raise Inductance Time Higher frequency: Voltage applied dI = (1/L)*V*dt Inductor Ripple Current (also determines peak switch current and Vout ripple) Lower frequency with higher inductance: Lower frequency: So we need to raise the inductance to keep the ripple current constant. This typically requires more turns/more wire which increases the size of the inductor. More wire also tends to increase the DCR (DC resistance) which leads to more power dissipation. Note: When creating a design, a rule of thumb for sizing an inductor is to try for +/- 15% inductor ripple current. This depends on the topology and the application and there can be a lot of variation (>100% ripple is desirable in some cases, particularly if the current is low. The circuit would then be running in discontinuous mode) If L is kept constant, ILpp increases So we need to increase L

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 Left Side Higher frequency Smaller footprint Right Side Lower frequency Lower resistance Here is a summary of optimizations done on a buck controller design. In general, at a high optimization number, the frequency is lower, which causes lower AC switching losses. However, it also requires more inductance to limit the ripple current. This results in a larger inductor due to the higher number of turns required and larger overall footprint. At the lower optimization settings, the opposite is true. Higher frequency requires less inductance and thus, results in smaller inductors and lower overall footprint. There are additional factors being weighted in the selection process including parasitic resistance (ESR, DCR), component cost and availability. small inductor large inductor

Optimization Summary To get high efficiency To get small footprint 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

Why Do Electrical Simulation? Identify Problems Design has been configured for stable operation BUT May want to verify under dynamic conditions Try Solutions Improve line/load transient response Minimize output voltage ripple Modify control loop Visualize Results Interactive waveform viewer allows detailed analysis of results

Electrical Simulation Specify sim type Esim page Click start to initiate sim Bode Plot Line Transient Load Transient Startup Steady State Waveform viewer Click to view waveforms

Waveform Viewer Click and drag down and to the right to zoom in Click and drag up and to the left to zoom out Click on a tile to add a waveform

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

Buck Schematics LM22680 PWM LM25576 ECM The LM22680 Simple Switcher has 9 external components, while the LM25576 has 13 external components LM25576 ECM

LM22680 vs LM25576 Vout for Load Transient (Pulse Width Modulated) LM25576 (Emulated Current Mode) has faster transient response recovery time Load Transient: 0.2 – 2.0A 50 usec rise/fall time Both devices have about the same excursion from nominal, but the LM22676 takes longer to recover from the load transient.

Overlay simulations Red: LM22680 (Pulse Width Modulated) Blue: LM25576 (Emulated Current Mode) has faster transient response recovery time

Why Do Thermal Simulation? Identify Problems Co-heating of parts not accounted for with ThetaJA Try Solutions Change copper thickness, airflow, ambient temperature, voltage, current Visualize Results Color temperature plot across the board Adjustable scaling © 2011 National Semiconductor Corporation.

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

WebTHERM® – Board Layout Inputs: Input voltage Current Top and bottom ambient temperature Copper thickness Airflow Board orientation Thermal Sim Page This is the initial parameter entry screen of WebTHERM® Thermal Simulator where you can view the printed-circuit-board layout, adjust the air flow velocity, change the copper area or thickness, adjust the top and bottom ambient temperatures, and specify the board edge boundary temperatures, either insulated or fixed. In addition you can enter the orientation of the board, and/or enter comments about the design. PC Board

WebTHERM® Results View interactions between components Diode and IC both generate heat Effect of backside copper and vias Top The simulation results allow the user to view interactions between components on the PC board. For example, the diode and IC both generate a lot of heat and if they are located close together there can be a problem. Bottom

LM3150 Controller .5oz copper thickness Low side FET is 117C Copper thickness is one of the factors that can make a big difference in designs that are dissipating a lot of power. In this case, .5oz copper was 49C higher than the 4oz copper. Vin: 14-22V Vout: 3.3V Iout: 6A

WebTHERM™ Solutions Use a Fan Or add a Heat Sink Design Specs: 500 LFM airflow Diode: 95C IC: 106C No airflow Diode: 134C IC: 146C Or add a Heat Sink No airflow Heat sink Diode: 91C IC: 52C Here is an example of how the WebTHERM Thermal Simulator can be used to solve a temperature problem. We have created a power supply design with Vin ranging from 20 to 22 volts, Vout = 5 volts and Iout = 5 amps. With this high-current design, the components tend to get quite hot. In the first simulation, using no fan or heat sink, the regulator is over 140C and the diode is over 130C. We can add a fan with an air velocity of 500 linear feet per minute and the simulation shows that the temperature of the IC and diode drop to less than 110 degrees. However, the design is still too hot. Another approach is to add a heat sink which brings the temperature of the IC down to less than 60C and the diode less than 100C. Other possibilities are to increase the copper area or thicken the copper. We are now done analyzing and optimizing our design and will proceed to the “Build It” step. Design Specs: Vin: 20-22V Vout: 5V Iout: 5A Note: heat sinks not yet enabled in new WEBENCH

Order a Build It® kit Build It Page Order custom prototype kit: On the Buy It page of Build It you have a number of options to get your prototype quickly. Here you can get a custom kit for your design. This is sent to you within 2 days via overnight carrier. The kit has all the parts for your design which allows you to solder your prototype faster than ever. You can also order free samples of the National Semiconductor regulator (up to 5) or order larger quantities of the regulator. Lastly, if a generic demo board is available, you can order that. However the generic demo board is not customized to your design. Order custom prototype kit: Bare board and parts Hourly pricing and inventory updates Shipped overnight

WEBENCH Visualizer Efficiency vs footprint vs BOM cost change axes optimized designs mouseover detail Efficiency vs footprint vs BOM cost

Why are solutions different?

WEBENCH® Tool Suite Power Architect WEBENCH Visualizer WEBENCH Power Designer

Real system means many supplies 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 Includes TI processors! Loads are pre-populated

Adding new/more loads

WEBENCH optimized now for systems

Analyze Performance, Cost, and Footprint for Selected Architecture

Complete design report Your design Inputs Supplies Schematics BOMs Local Languages Every time you adjust any of the WEBENCH® Power Designer designs, the documentation is updated and completely synchronized. The complete design report is dynamically created and can be printed or exported at any time. To share the project with another user, click on the Share Project button in the navigation header. Enter the recipient’s email ID and add notes. Then click on the Share This Project button. The entire project is shared at once. The recipient will receive an email with a link to the project and you will receive a confirmation after the design is received. Share design

WEBENCH Power Designer End to End design solutions On line selection, simulation and prototyping Dynamic design optimization: Provides supply configuration/topology based on size, cost, efficiency Other Features (Not discussed today): Visualizer, Power Architect, LED Designer, FPGA/uP Architect WEBENCH Design Tools save you time 52

Thanks

Appendix LED Lighting Gadgets

Phase (TRIAC) Dimmable LED Drivers

LM3466 Multi-String LED Current Equalization