1. WEBENCH® Power Designer & Power Architect Basics

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

3. 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

4. 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

5. 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

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

7. 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

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

9. 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

10. 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

11. 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

12. 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

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

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

15. 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

16. Key Optimization Parameters Graphed3
Frequency
IC Temperature
Footprint
Efficiency
BOM Cost
Power Dissipation
By Component

17. 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.

18. 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

19. 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

20. 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 (
Vth
Vth
Isw Vg
Vsw = -Vds
Switch Off On
Off
Trise
Tfall

21. 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

22. 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.

23. Inductor Ripple CurrentOn
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.

24. 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

25. 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

26. 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)

27. 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

28. 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

29. 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

30. 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

31. 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

32. 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

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

34. 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.

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

36. 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.

37. 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

38. 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

39. 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

40. 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

41. 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

42. 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

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

44. Why are solutions different?

45. WEBENCH® Tool Suite Power Architect WEBENCH Visualizer
WEBENCH Power Designer

46. Real system means many supplies
Many Loads, Many Supplies
Core Supply 3.0A
FPGA IO 0.5A
Vcca 0.2A
Flash 2.0A
SDRAM 1.0A
CCD 0.2A
PLL 0.2A
Motor Control 2.0A
Miscellaneous 2.0A
9 Loads and 5 Voltages

47. WEBENCH® Processor Architect
Includes TI processors!
Loads are pre-populated

48. Adding new/more loads

49. WEBENCH optimized now for systems

50. Analyze Performance, Cost, and Footprint for Selected Architecture

51. 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 ID and add notes. Then click on the Share This Project button. The entire project is shared at once. The recipient will receive an with a link to the project and you will receive a confirmation after the design is received.
Share design

52. 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

53. Thanks

54. Appendix
LED Lighting Gadgets

55. Phase (TRIAC) Dimmable LED Drivers

56. LM3466 Multi-String LED Current Equalization