WEBENCH® Power Designer &
Power Architect Basics
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Objectives

WEBENCH Overview

Walkthrough of WEBENCH Power Designer

Electrical and Thermal Simulation

Build it and Reporting
WEBENCH Tools
Power Designer
LED Designer
Sensor Designer
Active Filter Designer
PLL Designer
Amplifier Designer
Power supply and system architect design
LED driver design
Sensor analog front end design
Filter design and simulation
PLL implementation
Op amp design and simulation
WEBENCH Supports Broad Portfolio
12 Years Of Modeling And Verification
Circuit Calc & Sim model
CC but no Sim
WebTHERM /Build It
• LM201xx/3x3
• LM258x
• LM2700
• LM258x
• LM(2)5005/07/10/(11)
• LM259x
• LM2622
• LM259x
• LM5001/02/08/09
• LM267x
• LM3481
• LM267x
• LM(2)5085/88
• LM557x, LM2557x
• LM3224
• LM557x, LM2557x
• LM2734/35/36
• LM2267x, LM22680
• LM2267x, LM22680
• LM2743
• LM315x
• LM315x
• LM2830/31/32
• LM5118
• LMZ1050x
• LM2852/53/54
• LMZ1420x/200x
• LM3100/02/03
• LM3478/88
• LM34910/17/19/30
• LM3668
Switchers/Controllers/LED Drivers:
162 base part numbers in WEBENCH
• LM3670/71/73/74
Supported Topologies: Buck (over 60% of total designs), Boost,
Flyback and SEPIC (newest)
Coverage of WEBENCH Enabled Parts
(Buck Switchers)
• 40A-60A: LM(2)5119, LMZ22010 (interleaved)
Iout
• 30A: LM27402
• 20A: LM2743, LM5116
Vout Min
Vin Max
Vin Min
• 0.6V: LM283x, LM2743, LM3150, etc.
• 100V: LM5116
• 95V: LM5008/9
• 1.0V: LM2743
• 2.5V: LM3670/1
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Multilingual capability
• Chinese
• simplified
• traditional
• Japanese
• Korean
• Russian
• Portuguese
• German
(coming soon)
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Distributor & vendor versions
• Avago example
• Only contains Avago LEDs
And more…
• >110 component manufacturers & distributors
• >21,000 components
• Price and availability electronically updated hourly
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WEBENCH® Tool Suite
Altera
PowerPlay
Power Architect &
FPGAs
FPGA/Power Architect
WEBENCH Visualizer
WEBENCH Power Designer
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From optimized design to prototype
1. Enter reqs
2. Create design
3. Analyze design
4. Build It!
Custom prototype
overnight
Enter requirements
Optimize for:
• Footprint
• Efficiency
Generate schematic
& electrical analysis
Use graphs to
visualize design
Select design
Generate layout &
thermal analysis
Prototype
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Access WEBENCH tools from homepage or product folder
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WEBENCH Visualizer:
Calculates 50 Designs in 2 Seconds
Charts
Recommended Solutions
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WEBENCH Dashboard
Share Design
System
Summary
Optimizer
Circuits
Optimization
Graphs
BOM
Prototyping
& Reports
Charts
Power
Topology
Design
Reqs
System
Op Values
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WEBENCH® Tool Suite
Power Architect &
FPGAs
WEBENCH Visualizer
WEBENCH Power Designer
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WEBENCH Optimization Tuning
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WEBENCH Design Optimization
Optimization
Setting
1 – Smallest
footprint
2 – Lowest cost
3 – Balanced
Frequency
Highest
High
Medium
4 – High
efficiency
Low
5 – Highest
efficiency
Lowest
Component
Selection
Summary
• Smallest footprint
• Don’t care about cost
Smallest size but lowest
efficiency
• Lowest cost
High frequency means
smaller / cheaper
components
• In stock
• Low cost
Balanced approach
using IC’s middle
frequency
• Low DCR, ESR, Vf
• Low cost
Higher efficiency, with
low cost but larger
parts
• Low DCR, ESR, Vf
• Don’t care about cost
Highest efficiency but
largest parts
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Key Optimization Parameters Graphed
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Frequency
IC Temperature
Footprint
Efficiency
BOM Cost
Power Dissipation
By Component
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Schematic – Buck Converter
Components:
Input Capacitor
Regulator with integrated FET
Inductor
Catch Diode
Output Capacitor
Feedback Network
Feature Controls
Input
Load
Current Path with Switch On
Current Path with Switch Off
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Visualize Behavior – Power Dissipation
Efficiency = Pout / Pin
Pin = Vout * Iout + Pdiss
Switch:
DC: IswRMS2 * Rsw * DutyC
AC: ½ * Vin * Isw *
(Trise + Tfall)/Tsw
Quiescent: Iq * Vin
Diode:
Isw*Vf *(1-DutyC)
Inductor:
ILRMS2 * DCR
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Cout:
ICoutRMS2 * ESR
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
Isw
Vg
Vsw = -Vds
Switch Off
On
Off
Tfall
Trise
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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
Vth
Vth
Isw
Vg
Vsw = -Vds
Switch Off
On
Off
Trise
Tfall
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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
On
Time
Voltage
applied
dI = (1/L)*V*dt
Inductor Ripple Current (also determines
peak switch current and Vout ripple)
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Inductor Selection – Lower Frequency
Higher frequency:
On
Time
Voltage
applied
dI = (1/L)*V*dt
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
Lower frequency:
If L is kept
constant, ILpp
increases
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Inductor Selection – Raise Inductance
Higher frequency:
On
Time
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:
If L is kept
constant, ILpp
increases
So we need to
increase L
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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)
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Optimization – efficiency vs footprint
Left Side
Higher frequency
Smaller footprint
small inductor
Right Side
Lower frequency
Lower resistance
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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Why Do Electrical Simulation?
Identify
Problems
• Design has been configured for stable operation BUT
• May want to verify under dynamic conditions
• Improve line/load transient response
Try
Solutions
• Minimize output voltage ripple
Visualize
Results
• Interactive waveform viewer allows detailed analysis
of results
• Modify control loop
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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
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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
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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 LM25576
Vout for Load Transient
LM22680
(Pulse Width
Modulated)
Load Transient:
0.2 – 2.0A
50 usec rise/fall time
LM25576
(Emulated Current
Mode) has faster
transient response
recovery 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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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
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© 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
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WebTHERM® – Board Layout
Inputs:
•Input voltage
•Current
•Top and bottom
ambient temperature
•Copper thickness
•Airflow
•Board orientation
Thermal Sim Page
PC Board
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WebTHERM® Results
•View
interactions
between
components
•Diode and IC
both generate
heat
Top
•Effect of
backside copper
and vias
Bottom
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LM3150 Controller
.5oz copper thickness
Low side FET is 117C
4oz copper thickness
Low side FET is 68C
Vin: 14-22V
Vout: 3.3V
Iout: 6A
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Order a Build It® kit
Build It Page
Order custom prototype kit:
• Bare board and parts
• Hourly pricing and inventory updates
• Shipped overnight
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WEBENCH Visualizer
change axes
optimized designs
mouseover detail
Efficiency vs footprint vs BOM cost
Why are solutions different?
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WEBENCH® Tool Suite
Power Architect
WEBENCH Visualizer
WEBENCH Power Designer
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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
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WEBENCH® Processor Architect
Includes TI processors!
Loads are pre-populated
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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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Complete design report
Your design
• Inputs
• Supplies
• Schematics
• BOMs
• Local
Languages
Share design
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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
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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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