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© 2006 DCHopkinswww.DCHopkins-Associates.Com ABCs of Power Electronic Systems By Dr. Doug Hopkins & Dr. Ron Wunderlich DCHopkins & Associates Denal Way,

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1 © 2006 DCHopkinswww.DCHopkins-Associates.Com ABCs of Power Electronic Systems By Dr. Doug Hopkins & Dr. Ron Wunderlich DCHopkins & Associates Denal Way, m/s 408 Vestal, New York 13850-3035 dch@dchopkins-associates.com

2 © 2006 DCHopkinswww.DCHopkins-Associates.Com Our Professional Challenge The illiterate of the 21st century will not be those who cannot read and write, but those who cannot learn, unlearn and relearn. -- Alvin Toffler Dr. Toffler, Ph.D., is one of the world's preeminent futurists. As co-author of War and Anti-War, he sketches the emerging economy of the 21st century, presenting a new theory of war and revealing how changes in today's military parallel those in business.

3 © 2006 DCHopkinswww.DCHopkins-Associates.Com About the Course Authors? Dr. Doug Hopkins –PhD. Virginia Tech, VA Power Electronics Center –GE-CR&D, Carrier Air Conditioning Company(UTC), University at Buffalo, and DCHopkins & Associates (President) –R&D for advanced power electronic systems –dch@dchopkins-associates.com Dr. Ron Wunderlich –Ph.D. Binghamton University –IBM Power Systems, Celestica Power Systems, Transim Corp, and Innovative Design and Development (President) –Chief Engineer in design and development of power supplies for the computer and telecom industries. –raw@dchopkins-associates.com

4 © 2006 DCHopkinswww.DCHopkins-Associates.Com Course Topics 1. Overview of Power Electronics Technology 1a. Introduction to the power electronics system 2. Knowing your specifications 2a. Design for safety 3. Choosing the correct topologies 3b. Knowing where disaster can strike 4. Characterizing power components 4a. A safe operating area 4b. The dual faces of MOSFETS 4c. The circuit is a component 5. Design approaches and tools 5a. Simulating reality 5b. Input filtering 6. Design approaches and tools 6a. Design case study

5 © 2006 DCHopkinswww.DCHopkins-Associates.Com DCHopkins & Associates - Products 600W family of isolated DC/DC building blocks Pictures courtesy of Celestica, Incorporated Products designed by our Associates, photographed by our Associates. Multi-output telecom power supply

6 © 2006 DCHopkinswww.DCHopkins-Associates.Com DCHopkins & Associates - Products 30A high efficiency, high- transient isolated power supply Pictures courtesy of Celestica, Incorporated Isolated power supply for high- end micro-processor

7 © 2006 DCHopkinswww.DCHopkins-Associates.Com Where to go for news (other than suppliers)? News Sources http://www.darnell.com (PowerPulse Daily) http://www.poweronline.com (see electricnet) http//www.electricnet.com (see poweronline) http://www.powersystems.com http://www.eedesign.com http://www.psma.com http://www.ejbloom.com (see attached catalog) Conferences: –http://www.pels.org (the IEEE Power Electronics Society) http://www.apec-conf.org http://www.pesc06.org http://www.intelec.org

8 © 2006 DCHopkinswww.DCHopkins-Associates.Com Introduction to The System Power Processor Load Source

9 © 2006 DCHopkinswww.DCHopkins-Associates.Com Conversion or Supply Motor drives Linear Rotational Lighting Fluorescent HID Halogen Pulsed power Ignition Flash lamp Pulsed propulsion POWER CONVERSION Power Processor Load Source Types of Loads Conversion changes one energy form to another. Electrical Source

10 © 2006 DCHopkinswww.DCHopkins-Associates.Com Conversion or Supply Computer Applications – Desktops – Workstations – Servers – Mainframes Circuits: – CPU – Memory – Bus Terminators – Logic – Graphics Telecom Applications – Routers – Tele. Switches Circuits: – Optical Amps – CPU – Memory – Switch Cards – Logic POWER SUPPLY LOAD Power Processor Load Source Handheld Applications – PDAs – Notebooks – Cell-phones Circuits: – RF Amps – CPU/Logic – Memory – Display – Audio Amps Supply changes only the attributes.

11 © 2006 DCHopkinswww.DCHopkins-Associates.Com Uninterruptible Power Supply Systems Power Processor Electronic Circuit Clean AC Utility Noisy AC Utility Electronic Circuits are –Any electronic equipment that requires clean, reliable AC utility Computers, Telecom equipment, Home appliances Sources are –DC such as a battery or solar cells –AC utility that is of poor quality

12 © 2006 DCHopkinswww.DCHopkins-Associates.Com The System - Source Characteristics Power Processor Load Source SOURCE

13 © 2006 DCHopkinswww.DCHopkins-Associates.Com The System - Source Characteristics Power Processor Load Source THE POWER PROCESSOR Converts an unregulated power source to a regulated output. Like CPUs processing information - Power Supplies process energy. Linear Regulator Absorbs the energy difference Switch-mode Regulator Chops and averages energy packets

14 © 2006 DCHopkinswww.DCHopkins-Associates.Com Knowing Your Specifications and the Users Requirements

15 © 2006 DCHopkinswww.DCHopkins-Associates.Com Developing User Requirements Typically, User Requirements are derived through a polling process. This brings forward the highest-priority requirements, but are limited to personal experiences. A comprehensive approach uses a matrix of Five Taxonomies and Three Characteristics Responsible Design is from Cradle to Grave

16 © 2006 DCHopkinswww.DCHopkins-Associates.Com Grouping User Requirements Characteristic Unspoken Expectations Articulated Needs Unexpected Features Taxonomy Financial Legal Social Environmental Technical MATRIXED

17 © 2006 DCHopkinswww.DCHopkins-Associates.Com Taxonomies in User Requirements Financial requirements: represent cost and is base metric for other matrix entries. Legal requirements: include intellectual property as a source of revenue, strategic positioning or enticement. Social requirements: represent the corporate culture and image, global perceptions, and ethical conduct. Environmental requirements: represent government regulations and broader global concerns. Technical requirements: science based metrics related to energy forms and provide the SPECIFICATIONS.

18 © 2006 DCHopkinswww.DCHopkins-Associates.Com Characteristics of User Requirements Unspoken Expectations: –requirements for a product, process or service to be acceptable to all end users. Though labeled as unspoken, these may be new requirements that develop while a business has not been keeping up with the competition or market place, or basic requirements for entry into new markets. Articulated Needs: –typical, open and printed specifications. Discerns one user from another. There should be no question that these needs are requirements that must be met for each user. Unexpected Features: –exciters that make the product, process or service unique and readily distinguishable from the competition. (This is what the sales force lives for.) Features are speculative requirements.

19 © 2006 DCHopkinswww.DCHopkins-Associates.Com Example User Requirements Unspoken Environmental Expectation: the product is not lethally hazardous to shippers Articulated Technical Need: the products will operate from -40°C to +100°C. Unexpected Legal Feature: the product can have exclusive patent protection.

20 © 2006 DCHopkinswww.DCHopkins-Associates.Com Defining Specifications Power Supply I in V in I out V out Technical User Requirements provide the SPECIFICATIONS for each Energy Form. Power electronic circuits condition and convert many energy forms! Electric Magnetic Electromagnetic Thermal Mechanical Chemical Photonic

21 © 2006 DCHopkinswww.DCHopkins-Associates.Com Framework leading to Specifications Responsible Design is from Cradle to Grave. Characteristics Taxonomies Technical Characteristics – Energy Forms – Conditions Start-up Shut-down Normal operation Fault operation

22 © 2006 DCHopkinswww.DCHopkins-Associates.Com Electrical Specs Vin, Iin AC Vin, Iin DC Input Vout, Iout Output PGood, On/Off Controls Efficiency Misc Electrical Spec

23 © 2006 DCHopkinswww.DCHopkins-Associates.Com DC Input Spec Typical DC sources: –Car Battery typical 12 volts with 11 to 14 volts variation –Solar Cell 0.5 to 1 volt per cell depending on sunlight –Telecom Bus typical 48 volts with 36 to 72 volts variation –PC Internal 5V Bus 5 volts, +/- 10% Example: A Telecom bus has a Vin operating range of 36 to 72 volts –If the input voltage drops below 36V, typically, a PS will shut down. –If the input voltage exceeds 72V, typically, a PS will be damaged by the excessive high voltage. A PS can be designed so it can handle short duration of high input voltage such as line transients due to lightning. This is known as a surge rating. For example, this PS may have a surge rating of 100V for 100usec. Specifying Vin depends on the source voltage range.

24 © 2006 DCHopkinswww.DCHopkins-Associates.Com DC Input Spec - I in, P out, P in, Pout (output power) = Vout x Iout Pin (input power) = Vin x Iin (efficiency of the PS) = Pout / Pin –Typically between 0.5 to 0.98 Substituting and solving for Iin Iin = (Vout x Iout) / (Vin x ) Iin is the current drawn by the PS and derived by Note: Worst case - Iin occurs at lowest value of Vin, e.g. for telecom PS most current is at Vin=36 volts.

25 © 2006 DCHopkinswww.DCHopkins-Associates.Com Irip Iin Time DC Input Spec Specified as peak-to-peak. Occurs at usually < 10Mhz Typically, < 10% of max Iin E.g., if Iin max is 10A, Irip p-p should < 1A Iin will have ripple current, Irip, from the switching stage within the PS.

26 © 2006 DCHopkinswww.DCHopkins-Associates.Com DC Input Spec Iin will have switching noise that occurs at >10Mhz. The noise is due to the internal capacitive coupling parasitics Typically, the peak-to-peak noise is less than 1% of max Iin Iin will have switching noise.

27 © 2006 DCHopkinswww.DCHopkins-Associates.Com DC Input Spec Surge current, Isurge, is due to charging of internal capacitors Usually Isurge is less than 5 times max Iin This can cause problems with fusing. Iin will have a surge during start-up.

28 © 2006 DCHopkinswww.DCHopkins-Associates.Com Specifying Vin depends on the source voltage range AC Input Spec Typical AC sources for the home –Doorbell, heating systems 24Vrms +/- 30% –Household wiring Typically 110Vrms with 90 to 130 range –Electric stoves Typically 220Vrms with 180 to 260 range Actually, 220Vrms with a center-tap is delivered to the home. 110Vrms is derived from the center-tap Typical AC sources for business (single phase derived from three phase) –Office wiring Typically 120Vrms with 90 to 140 range –Industrial/Computer Typically 208Vrms with 180 to 260 –Smaller businesses will use the household AC utility Europe and some other countries are wired with either 208Vrms or 220Vrms

29 © 2006 DCHopkinswww.DCHopkins-Associates.Com AC Input Spec Vin for typical products –Desktop PC sold in the US, 90Vrms – 140Vrms –Desktop PC sold Worldwide, 180Vrms – 260Vrms –High-end servers sold worldwide, 180Vrms – 260Vrms –Desktop PC with universal PS, 90Vrms – 260Vrms –Why not use a universal PS in all desktop PCs ? Universal PS are more expensive and difficult to design Operating frequency for Vin is specified as –USA - 60Hz; Europe and other countries - 50Hz, range is +/-3Hz A universal PS operates from 47Hz to 63Hz –This is not a cost or a design problem

30 © 2006 DCHopkinswww.DCHopkins-Associates.Com AC Input Spec - Vin-rms AC sources are: –Single Phase –Three Phase (>5kW, not covered) Vin is understood to be Vin-rms; –Vin-rms = Vpk / 1.4142 * RMS makes calculations easier –For DC, Pin = Vin x Iin –For AC, Pin = Vin-rms x Iin-rms *For single frequency sine wave Power Supply I in V in I out V out Vpk Vin is from the wall outlet or a UPS for Off-Lineconverters

31 © 2006 DCHopkinswww.DCHopkins-Associates.Com AC Input Spec - sags, surges, and transients AC voltage will have transients and surges –2000V spikes are not uncommon Florida is the worst US state –Due to lightning, industrial equipment and solar flares –The front-end PS circuitry must be able to shunt this energy The PS cannot have direct connection between input and output. Hence, isolation is required. This is a safety requirement. AC supply has brown outs, sags, or drop outs in power –This occurs when The utility transformer in a sub-station goes bad The grid becomes overloaded from air-conditioners, etc. Solar flares induce too much voltage and pop the breakers –These occur quite often More than 99% of the drop outs are less than 20ms in length

32 © 2006 DCHopkinswww.DCHopkins-Associates.Com When AC momentarily is interrupted AC Input Spec - Hold-up Time For non-mission-critical devices –e.g., televisions, radios, VCRs –PS can shut down temporarily For mission-critical devices –e.g., high-end servers –PS shall maintain operation for a loss of AC up to 20ms –After 20ms it can shut down This is known as hold-up time This is accomplished by a large energy storage device such as a capacitor in the input (PFC). –Typical specifications for hold-up is 20ms.

33 © 2006 DCHopkinswww.DCHopkins-Associates.Com Ideally, Iin should follow Vin emulating a resistor AC Input Spec - Power Factor A bridge rectifier with a large capacitance is usually at the PS input. –Iin, with respect to Vin, will be distorted. –Iin-rms is now significantly higher than for a resistor input to have the same usable energy flow. –The distortion adds frequency harmonics.

34 © 2006 DCHopkinswww.DCHopkins-Associates.Com AC Input Spec - Power Factor (cond) Apparent power is Pa = Vin-rms x Iin-rms Real power is the averagePr = Vin x Iin Power Factor, PF PF = Real Power / Apparent Power The lower the PF, the higher the Iin-rms for the given power The problems with lower PF are –Wire sizes must be increased to handle the higher Iin-rms current Power Loss increases by the square of current! –This is extra power for which the feeders and fuses must be size – Iin is rich in harmonics which adds noise and circulating currents in 3-phase systems

35 © 2006 DCHopkinswww.DCHopkins-Associates.Com AC Input Spec - Inrush Current Usually, peak Iin is specified to be <5X the steady- state Iin-rms. Another factor to consider is fusing and circuit breakers. If the inrush current is too high or can occur throughout the day, fuses and circuit breakers can be weakened, damaged, or open up. Like DC, Iin has inrush issues with AC applications.

36 © 2006 DCHopkinswww.DCHopkins-Associates.Com Total Harmonic Distortion, THD - the same for your stereo as for the power supply AC Input Spec - THD Any waveform can be broken down into a sum of sine waves with different amplitudes If there is any distortion, then –I = 1.414 x [I1sin(2 ft)+I2sin(4 ft)+I2sin(6 ft)+…] –I1 is the rms of the fundamental current waveform –I2 is the second-order harmonic, I3 is third, etc. –The Total Harmonic Distortion is then THD = {sqrt[ (I2)^2 + (I3)^2 + (I4)^2 + …] / (I1)} x 100% A good value for THD < 5%

37 © 2006 DCHopkinswww.DCHopkins-Associates.Com AC Input Spec - Noise Conducted noise current is measured on the line cord. –The frequency is less than 30Mhz –A LISN box is connected to the cord to filter out the 50/60hz –A frequency-spectrum analyzer then displays the noise spectrum Federal specifications must be met If the frequency is > 30Mhz, this is known as radiated –This is measured with an antennae usually 10 meters away –At these frequencies, line cords and cables become very effective antennae Federal specifications that must be met Conducted versus Radiated Noise

38 © 2006 DCHopkinswww.DCHopkins-Associates.Com Vout Specs Line, Load & Temperature Load Step Ripple & HF Noise Long Term Stability Static Regulation Dynamic Regulation Noise Drift V OUT

39 © 2006 DCHopkinswww.DCHopkins-Associates.Com Static Regulation Line Regulation –% change in output voltage versus input voltage at a given load –Typically 1-2% Load Regulation –% change in output voltage versus load at a given input voltage –Typically 0.1-3% Vout Temperature Effect –% change in output voltage versus temperature for given input and load –Typically 0.2-1%

40 © 2006 DCHopkinswww.DCHopkins-Associates.Com Static Regulation Cross-Regulation (multi-output converters) –Change in output voltage of channel 2 for a change in load on channel 1 at a given input voltage –Typically 0.1-10%

41 © 2006 DCHopkinswww.DCHopkins-Associates.Com Change in output voltage is due to the dynamic behavior of the power supply Dynamic Regulation The output voltage initially changes because of the I step x ESR of the output cap (5A x 0.3ohms) The second part is due to the loop response of the converter The change in output voltage is measured from the nominal output voltage 5% for this example

42 © 2006 DCHopkinswww.DCHopkins-Associates.Com Another effect shows up as L x (di/dt) Dynamic Regulation This is due to inductance of –Output capacitor –Connector –Bus distribution This is not always included in the spec. Could typically be < 5%

43 © 2006 DCHopkinswww.DCHopkins-Associates.Com Vout Time Vrip Ripple and Noise Ripple –Triangular-shaped current at the switch frequency –Due to inductor current x ESR of output cap High Frequency Noise –Noise > 10 x fSW –Either random or the excitation of high-frequency parasitics. Typically 0.2-3%

44 © 2006 DCHopkinswww.DCHopkins-Associates.Com Over time, a reference voltage can change. Drift Drift is due to –Aging –Soldering –Package compression Typically < 0.2%

45 © 2006 DCHopkinswww.DCHopkins-Associates.Com Question - How can you improve the transient response of the converter without… changing the components or changing the switching frequency?

46 © 2006 DCHopkinswww.DCHopkins-Associates.Com Answer Use adaptive control (positioning) –At no load, start at +X 1 % above nominal Vout –At full load, change Vout to be X 2 % below nominal Vout In the previous example, dynamic regulation was 5% This can be changed to 3% dynamic regulation by modifying V REF for the control loop scheme Common in ICs

47 © 2006 DCHopkinswww.DCHopkins-Associates.Com Iout Specs Below is a typical Iout load behaviour Iout Time di/dt rate Minimum current Maximum current I step Over current trip point

48 © 2006 DCHopkinswww.DCHopkins-Associates.Com Question What happens to current in C OUT if I OUT s frequency >> than the bandwidth of the converter ?

49 © 2006 DCHopkinswww.DCHopkins-Associates.Com Answer Normally, the ripple current in Cout is the same as the inductor current If the load is switching faster than the bandwidth of the converter –the ripple current in Cout is due to Iout (load shift). –the converter will not respond to the load changes so the current it delivers will be the average of Iout The ripple current in Cout due to Iout may be significantly higher than that due to the inductor current This condition occurs with most modern micro-processors when executing certain software Local decoupling caps help solve this problem

50 © 2006 DCHopkinswww.DCHopkins-Associates.Com Design For Safety Standards, Certificates & Regulations

51 © 2006 DCHopkinswww.DCHopkins-Associates.Com Safety EMC Robustness Features Corporate Standards Standards, Certificates & Regulations A power supply has many standards and regulations to meet Only the major ones will be covered

52 © 2006 DCHopkinswww.DCHopkins-Associates.Com Safety - http://www.i-spec.com To sell a product and/or to be protected from liability, the product must be approved by a safety agency –Europe has Conformity European Mark –Canada has Canadian Safety Agency –US has Underwriters Laboratories Many countries have their own safety agencies The Product Designer's on-line guide to compliance with the International Safety Standard for Information Technology Equipment, IEC 60950 i-Spec also covers national standards based on IEC 60950, including EN 60950, UL 1950/CSA C22.2 950, AS/NZS 3260. http://www.i-spec.com Most countries follow standard IEC-60950

53 © 2006 DCHopkinswww.DCHopkins-Associates.Com Safety For example: –A product that will operate from 240VAC requires that the primary-secondary spacing be greater than 8mm –The FR4 Card must meet UL 94V-0 standard for flammability There is even safety consideration for battery-operated equipment when the battery fails short To obtain safety approval –The product must be taken to an agency for testing –Performed by a person within the company who has been certified by the safety agency Approval by one safety agency will be accepted by others –To obtain CE and CSA approval for a power supply that has been approved by UL, only the test report need be shown Many labs will do all the required testing and the paper work for a fee

54 © 2006 DCHopkinswww.DCHopkins-Associates.Com Electro-Magnetic Compatibility (EMC) EM emission limits are required by law for products –For the US, FCC part 15 –For Europe, CSIPR –Both are similar Electro-Magnetic Compatibility - (Love / Hate) EM Emission - EM Susceptibility Class A typically for industrial equipment Class B typically for commercial / home equipment Class B is 10dB more stringent

55 © 2006 DCHopkinswww.DCHopkins-Associates.Com Conducted or Emitted Noise is measured through a device called a LISN on the AC cord LISN – Line Impedance Stabilizer Network is a set of filters that filters signals above 60Hz to a spectrum analyzer The noise is measured with an antennae 10 meters away All testing is done in a shielded chamber Certifications must come from approved sites 30 MHz

56 © 2006 DCHopkinswww.DCHopkins-Associates.Com Why 30 MHz? Question –Why are measurements done through the line cord at 30Mhz? Answer The speed of light, c, is 300 x 10 6 m/s At f = 30Mhz (30 x 10 6 /s), the wavelength (=c/f) is 10m –At frequencies <30Mhz, the emitted noise is carried out in the wiring which is not an effective antennae –At frequencies >30Mhz, emitted noise is radiated from the line cord and circuit wiring since these now become effective antennas

57 © 2006 DCHopkinswww.DCHopkins-Associates.Com Susceptibility These standards help the user design a product that will last a reasonable time in every day environments. There are no requirements to meet any of these standards. However, they contain a wealth of experience. Lower Susceptibility is increased Robustness

58 © 2006 DCHopkinswww.DCHopkins-Associates.Com Susceptibility - Circuit Card Effects For example –For connectors, FR4 cards and sheet metal –Spacing between primary to secondary wring on a FR4 card is well defined in safety guidelines –IPC defines the spacing between primary-to-primary and secondary-to-secondary wiring –If the primary-to-primary spacing is reduced below the IPC guidelines, arcing can occur There is no facility to test against the IPC spec. This is left up to the designer The Institute for Interconnecting and Packaging Electronic Circuits developed standards for the packaging of products

59 © 2006 DCHopkinswww.DCHopkins-Associates.Com Susceptibility - AC Utility Effects Surges are caused by abrupt load changes and bank switching Transients are caused by lightning strikes and line faults. IEC 801-4 and IEC801-5 provide test procedures that ensure your product survives most cases These tests can be performed by the designer with the right equipment or by outside labs The AC utility line has surges and transients

60 © 2006 DCHopkinswww.DCHopkins-Associates.Com Susceptibility - Electro-static Discharge These occur when products are physically handled IEC 801-2 provide test procedures to ensure your product survives most cases These tests can be performed by the designer with the right equipment or by outside labs Products must also be protected or withstand electro-static discharges (ESD)

61 © 2006 DCHopkinswww.DCHopkins-Associates.Com Susceptibility - ElectroMagnetic The product should behave as expected with EM fields up to a certain strength The standards for this are –IEC 810-3 for radiated susceptibly –IEC 810-6 for conducted susceptibly Testing for this is usually performed in EM shield chambers, same place as for FCC approval EM Susceptibility tests how sensitive a product is to EM emissions

62 © 2006 DCHopkinswww.DCHopkins-Associates.Com Corporate Standards Corporate Standards should be all encompassing –They can toughen existing requirements, such as IPC guidelines –They can be guidelines on how a product should be designed Topology A is chosen over topology B SMT vs. PTH –They can be guidelines on how a product looks Placement of labels Color of products –They can be guidelines on de-rating of components Some product specs will cite MIL-217F or Bellcore Corporate standards are policed within the company

63 © 2006 DCHopkinswww.DCHopkins-Associates.Com Corporate Standards - Features: ENERGY STAR Features are specifications that make a product more valuable Some features later become requirements ENERGY STAR –A feature developed by the US-EPA –Products must reduce their power consumption significantly for a period of time or when not in use, known as sleep mode –These tests can be performed by the designer with the right equipment or by outside labs The guideline for computers can be found at http://www.epa.gov/nrgystar/purchasing/6a_c&m.html#specs_cm

64 © 2006 DCHopkinswww.DCHopkins-Associates.Com Corporate Standards - Features: PFC & THD In US, still a feature In Europe, this has become a requirement This is an example of a feature that has become a requirement The standard for this is IEC-555 This test can be performed by the designer with the right equipment or by outside labs Low Power Factor and Low THD apply to AC off-line supplies

65 © 2006 DCHopkinswww.DCHopkins-Associates.Com Choosing the Correct Topology

66 © 2006 DCHopkinswww.DCHopkins-Associates.Com Load (V OUT ) dc source (V IN ) P L = (V IN - V OUT ) * I OUT Linear Regulators Switch is used as programmable resistor Fast dynamic response Minimal filtering Poor efficiency Relatively large with heat sink

67 © 2006 DCHopkinswww.DCHopkins-Associates.Com load (V OUT ) dc source (V IN ) P L : steady state + switching Switchmode Regulators Switch is used as a chopper Dynamic response depends on switching frequency Requires filtering High efficiency High density chopper (f T ) filter (f F )

68 © 2006 DCHopkinswww.DCHopkins-Associates.Com Demystifying the Circuits - Duality Using Simple principles of Duality Duality Current is voltage; Voltage is current L is C; C is L R is R is R Series is parallel; Parallel is series Transistor is diode; Diode is Transistor Open is closed; Closed is open

69 © 2006 DCHopkinswww.DCHopkins-Associates.Com Demystifying the Circuits – Non-isolated Buck load dc source dc source load Buck/Boost load Boost dc source DUALITY CASCADE DUALITY Cuk not covered

70 © 2006 DCHopkinswww.DCHopkins-Associates.Com Demystifying the Circuits – Conversion Ratios Buck Regulator (Step-down converter) Boost Regulator (Step-up converter) Buck/Boost (Up/down converter) V OUT V IN = D V OUT V IN 1 1-D = V OUT V IN -D 1-D = D: duty cycle of switch T ON T PERIOD T ON T PERIOD D =

71 © 2006 DCHopkinswww.DCHopkins-Associates.Com Demystifying the Circuits – Transformer Isolated Buck/Boost Isolated Buck Isolated dc source load Flyback dc source load Forward

72 © 2006 DCHopkinswww.DCHopkins-Associates.Com Demystifying the Circuits – Bridge Half Bridge Full Bridge Buck derived topologies dc source LOAD dc source LOAD

73 © 2006 DCHopkinswww.DCHopkins-Associates.Com Demystifying the Circuits – Resonant Bridge Series Resonant dc source LOAD Parallel Loaded Series Resonant LOAD dc source

74 © 2006 DCHopkinswww.DCHopkins-Associates.Com Partially Resonant Topologies Discontinuous-Resonant topologies known as –Zero-Voltage Switched circuits –Zero-Current Switched circuits Resonant Transition topologies –Zero-Voltage PWM topologies Characteristics: –Uses internal parasitics for nearly lossless switching –Fairly involved design approach –Next level of sophistication Beyond this course

75 © 2006 DCHopkinswww.DCHopkins-Associates.Com Knowing Where Disaster Can Strike Do you have the knack?

76 © 2006 DCHopkinswww.DCHopkins-Associates.Com Disaster is Only Nanoseconds Away Inductive Switching 101 or Understanding the Waveforms Buck Load Buck-Boost Load You can be a rich power electronics designer too! It is all in battling Mother Nature. She likes continuity and easy flow, e.g. Sinewaves, exponentials and Gaussians. We give her v=L*di/dt and i=C*dv/dt

77 © 2006 DCHopkinswww.DCHopkins-Associates.Com Inductively Induced Voltage Power Mosfets can switch 10A in 5ns Internal lead inductance could be 5 nH each terminal v=L*di/dt, or lead inductance creates a 20 V spike. Lower the Mosfet rating, the faster the device All parameters work against you Thank you, Mother Nature

78 © 2006 DCHopkinswww.DCHopkins-Associates.Com Inductive Switching - Ideal Circuit

79 © 2006 DCHopkinswww.DCHopkins-Associates.Com Inductive Switching - Ideal Circuit, Real Switch

80 © 2006 DCHopkinswww.DCHopkins-Associates.Com Inductive Switching - Diode Inductance

81 © 2006 DCHopkinswww.DCHopkins-Associates.Com Inductive Switching - Diode Capacitance

82 © 2006 DCHopkinswww.DCHopkins-Associates.Com Inductive Switching - Circuit Inductance

83 © 2006 DCHopkinswww.DCHopkins-Associates.Com Inductive Switching - Slower Switch Transition Vds is worse if Fet is slowed down. Suspect something with model. Everything else ok.

84 © 2006 DCHopkinswww.DCHopkins-Associates.Com Inductive Switching - Snubbing transients

85 © 2006 DCHopkinswww.DCHopkins-Associates.Com Characterizing Power Components

86 © 2006 DCHopkinswww.DCHopkins-Associates.Com Semiconductors Zeners –typical operation –transient suppression Diodes Rectifiers Fast recovery Ultra-fast recovery –Reverse Recovery Charge –Forward turn-on delay –Package parasitics Varistors (MOVs) –clamps (not crowbars) –should thermally fuse Transistors –Power Mosfets vertical structure –IGBTs –TopSwitch –modules –Bipolars Triggered semiconductors –SCRs crowbar applications Phase-controlled bridges high power –Unijunctions

87 © 2006 DCHopkinswww.DCHopkins-Associates.Com Do's and Don'ts of Using MOSFETs Be Mindful of –Reverse blocking characteristics of the device A vertically conducting device –Handling and testing power HEXFETs –Unexpected gate-to-source voltage spikes –Drain or collector voltage spikes induced by switching Pay attention to circuit layout Do not exceed the peak current rating Stay within the thermal limits of the device Be careful when using the integral body-drain diode Be on your guard when comparing current ratings

88 © 2006 DCHopkinswww.DCHopkins-Associates.Com MOSFET Gate Drive Characteristics Gate drive -vs- base drive –Driving HEXFETs from linear circuits –TTL gate drive for a standard HEXFET? –The universal buffer The most important factor in gate drive: The impedance of the gate drive circuit Gate drive approaches –Simple and inexpensive isolated gate-drive supplies Optocouplers, pulse transformers, choppers, photovoltaic generators –Bootstrap gate-drive supply Maximum gate voltage and the use of Zeners Driving in the MHz? Use resonant gate drivers –Power dissipation of the gate drive circuit is seldom a problem

89 © 2006 DCHopkinswww.DCHopkins-Associates.Com Paralleling MOSFETs General Guidelines –Steady State Sharing The inherent positive temperature coefficient provides dc (steady state) sharing while in the on-state! –Dynamic Sharing at Turn-On Requires close matching of gate-threshold voltages Avoid gate resonance by using ferrite gate beads (few nH) Must have matched inductive paths Clamping MOSFETS are beneficial –Dynamic Sharing at Turn-Off Requires some matching of gate-threshold voltages Requires close matching of Miller Capacitance path Must have matched inductive paths

90 © 2006 DCHopkinswww.DCHopkins-Associates.Com Diode Reverse Recovery Buck Load tata tbtb tntn I RR IFIF Abrupt Recovery Recovery produces sharp current transients and EMI tata tbtb tntn I RR IFIF Soft Recovery

91 © 2006 DCHopkinswww.DCHopkins-Associates.Com Safe Operating Area - the holy grail SOA combines transient and thermal limits IDID V DS Steady state (DC) limit Fusing current Thermal path limit Transient thermal limit Breakdown limit Switching speed dc -to- pulsed MAXIMUM POWER AREA

92 © 2006 DCHopkinswww.DCHopkins-Associates.Com Capacitors - Circuit Equivalent Ceramic –high frequency –sensitive to thermal transient Tantalum –polarized, also organic leads –high energy density Electrolytic, also oscon –polarized –highest energy density Staged for reducing ESR C Equivalent Circuit –R, L, C –limited internal temperature from RMS heating, i.e. current ripple ESL ESR leakage

93 © 2006 DCHopkinswww.DCHopkins-Associates.Com Magnetics - Circuit Equivalent XlXl XpXp XsXs RpRp CsCs Approx.: X l = 10 *X p Transformers –Leakage is loss of coupling from primary to secondary –Skin effect is determined by copper and core magnetic fields litz wire and foil help in high-frequency designs –Thermal hot-spots of most concern: from high flux densities in core from eddy current losses in core and wires potting can trap heat

94 © 2006 DCHopkinswww.DCHopkins-Associates.Com The Dual Faces of Power MOSFETS Getting the heat out with Synchronous Rectification

95 © 2006 DCHopkinswww.DCHopkins-Associates.Com Synchronous Rectification - Output Drop For output voltages < 3.3V, the best case efficiency can be approximated by Vd is the voltage drop due to the output diodes As voltage requirements from micro-processors and logic drop, efficiency becomes a problem load Boost dc source

96 © 2006 DCHopkinswww.DCHopkins-Associates.Com Synchronous Rectification - Efficiency The best Schottky diode voltage is 0.25V and high current Schottky diodes are as high as 1V For example, 1V@100A converter with 0.5V for Vd, can have an efficiency of 67% best case For every 100W out, 50W is wasted as heat! Other advantages for increasing efficiency –Greater utilization of AC feeder capacity –Reduced electrical bill for the customer –Increased reliability with less thermal issues –More green friendly

97 © 2006 DCHopkinswww.DCHopkins-Associates.Com Synchronous Rectifiers Solution is to use Synchronous Rectifiers Replace or parallel the output diode with a low Rds-on Fet For this to work, the Fet must turn on when the current is in the direction of the diode I x Rds-on < Vd Efficiency of 90% can be achieved with 1V@100A power supply! I

98 © 2006 DCHopkinswww.DCHopkins-Associates.Com Synchronous Rectifiers - Notables –If the current reverses and the Fet is on, you have a short-circuit condition across, usually, a transformer –Timing is critical –The MOSFET body diode may come on –Placing a Schottky diode in parallel with the body diode will not, in all cases, reduce power loss – Ramp down effect –Very low Rds-on Fets require a large amount of gate drive energy For example, a 1V@100A converter, 2% efficiency loss to gate drives is not uncommon What to watch out for

99 © 2006 DCHopkinswww.DCHopkins-Associates.Com – Circulating current can be as high as several hundred amps – Solution is to shut sync rect off at light loads Synchronous Rectifiers - Parallel Modules –Some PS can source and sink current –At light loads, this could happen with parallel modules

100 © 2006 DCHopkinswww.DCHopkins-Associates.Com The Circuit is a Component Insights into Power Packaging

101 © 2006 DCHopkinswww.DCHopkins-Associates.Com + Electric Magnetic Electromagnetic Thermal Mechanical Chemical Photonic Electrical v. Physical Circuits Power electronic circuits [PHYSICAL CIRCUITS] condition and convert many energy forms! We do not do ONLY electrical designs

102 © 2006 DCHopkinswww.DCHopkins-Associates.Com Skin Effect Finite resistance Lead Inductance Coupled Capacitance Inter-Conductor Capacitance Typical Electrical Structure

103 © 2006 DCHopkinswww.DCHopkins-Associates.Com R = l / (t × w) let l / w = 1 = one square R sheet = / t [ / sq. ] A corner is 0.559 squares w t l l Conductor Resistance -Sheet Resistance

104 © 2006 DCHopkinswww.DCHopkins-Associates.Com 1 oz. copper is weight for one square foot Thickness and Resistance from Common Conductors Conductor Thickness

105 © 2006 DCHopkinswww.DCHopkins-Associates.Com Calculate the voltage drop and power loss of the output leads for a 5V, 100A supply. Consider 1oz., 2oz. and 3oz. copper conductors. No. of squares for both sides is: Squares = = For 2oz. copper R total = = V leads = P leads = Terminal ~.22 ~1 Cap ? DC Power Supply Example - Output Conductor Resistance

106 © 2006 DCHopkinswww.DCHopkins-Associates.Com Calculate the voltage drop and power loss of the output leads for a 5V, 100A supply. Consider 1oz., 2oz. and 3oz. copper conductors. No. of squares for both sides is: Squares = 2(1 + 0.56 + 0.56 + 0.22) = 4.68 sq. For 2oz. copper R total =(0.252 m sq) (4.68 sq) =1.18 m V leads = (1.18 m mV or 2.8% P leads = (118 m ) (100 A) 2 = 12 W Terminal 0.56 ~.22 ~1 Cap ~1 0.56 DC Power Supply Example - Output Conductor Resistance

107 © 2006 DCHopkinswww.DCHopkins-Associates.Com Output Conductor Resistance

108 © 2006 DCHopkinswww.DCHopkins-Associates.Com Substrate Coupling Example: Conductor #1: 100mils x 1 inch Conductor #2: 400mils x 1 inch Substrate: ceramic loaded polymer, 3 mils thick, r = 6.4 Find Capacitance: C = Coupled Capacitance

109 © 2006 DCHopkinswww.DCHopkins-Associates.Com Coupled Capacitance Substrate Coupling Example: Conductor #1: 100mils x 1 inch Conductor #2: 400mils x 1 inch Substrate: ceramic loaded polymer, 3 mils thick, r = 6.4 Find Capacitance: C 1 = 47.9 pF,C 2 = 192 pF C = C 1 series with C 2 = 38.3 pF

110 © 2006 DCHopkinswww.DCHopkins-Associates.Com Example: Switching current coupled into header from FET drain. FET: 400mils 2, t f = 20 ns (+20 mil conductor periphery) (+100 mils 2 drain bond pad) (+200 mils x 400 mils drain lead) Substrate: Al 2 O 3 25 mils thick, r = 9.4 Voltage source: 425 V dc continued VdVd Ground Coupling

111 © 2006 DCHopkinswww.DCHopkins-Associates.Com Find Capacitance: Find switching current: i = C (dV/dt ) i = 400mils 2 Bond Pad 100mils 2 Drain Lead 100x200mils ? 20mils Ground Coupling (continued)

112 © 2006 DCHopkinswww.DCHopkins-Associates.Com 400mils 2 For ceramic loaded polymer C = 136 pF and i = 2.9 A Bond Pad 100mils 2 Drain Lead 100x200mils 20mils Ground Coupling (continued) Find Capacitance: A = 0.284 in2 = 183 mm2 d = 25 mils = 0.635 mm Then: C = 24 pF (d-s Cap) Find switching current: i = C (dV/dt ) = 24 pF (425/20ns) i = 0.51 A

113 © 2006 DCHopkinswww.DCHopkins-Associates.Com Self Inductance of Conductors Minimum is non-coupled in free space X e ( sq ) = L l L = R = ( 2 ) -1 l = (sinh sin ) / ( cosh cos ) t / t is the thickness (m) f, skin depth is conductivity in (s/m) f is frequency is permeability ( x 10 -7 H/m) Inductive Effects Non-Transmission Line Mode

114 © 2006 DCHopkinswww.DCHopkins-Associates.Com Example - High Frequency Lead Inductance Calculate the per-square self-inductance of a 1oz, 2oz and 3oz copper lead needing to conduct a 1MHz signal. For 1oz copper: m, t / L m sq, l = 0.172 X e = 22.4 sq, or L e = 3.57 pF / sq Self-Inductance, Cu @ 1MHz Note: max self- inductance = ( 4 f -1 / 2 Inductive Effects

115 © 2006 DCHopkinswww.DCHopkins-Associates.Com Non-ferrous headers Aluminum Copper Si C Al Si C Ferrous headers / substrates Invar ( 64% iron, 36% nickel ) Kovar ( 54% iron, 29% nickel, 16% cobalt) Ferrite (substrates) Porcelainized steel (substrate) Inductive Loops

116 © 2006 DCHopkinswww.DCHopkins-Associates.Com Junction Temp (C) Failure Rate ( /10 5 runs) Junction Life Statistics 50, 0.005 100, 0.05 150, 0.2 Temperature as the Culprit

117 © 2006 DCHopkinswww.DCHopkins-Associates.Com Factors affecting T Convection/conduction in medium Chip size Chip attach Heat spreader Conductor type and thickness Substrate type and thickness Substrate attach Heatsink Thermal Issues

118 © 2006 DCHopkinswww.DCHopkins-Associates.Com Power Supply P 0 / P i, P l = P 0 ( 1 - Load P 0, zero % efficient electrically For first-level type packaging (e.g.. chip and wire) the thermal area densities are equal: P l / A ps = P L / A L Load P l P0P0 PiPi PLPL heat PwrSupply Rule of Areas (Hoppys Rule)

119 © 2006 DCHopkinswww.DCHopkins-Associates.Com For thermal enhancements (e.g. thermal vias) a Thermal Density ratio, TD r, is defined TD r = k e, l / k e, ps where k e is an equivalent thermal conductivity for that area. Then TD r ( P l / A ps ) = P L / A L A ps / A L = TD r ( A ps /A L TD r =1 Rule of Areas (continued)

120 © 2006 DCHopkinswww.DCHopkins-Associates.Com R = 1 t k A iq v T RR Chip Solder Conductor Spreader Substrate Attach Baseplate Heatsink 1 l A R = R [ ] = v[V] / i [A] R [ o C/W] = T [ o C] / q [W] Thermal Resistance Model - 1D

121 © 2006 DCHopkinswww.DCHopkins-Associates.Com Thermal Typical Thickness T(°C) Material Conductivity R /cm 2 (mils) IGBT (W/m °C) (°C/kW cm 2 ) @0.2kW/cm 2 Silicon (Si) Solder (95Pb-5Sn) Molybdenum (Mo) Alumina (Al 2 O 3 ) Aluminum Nitride (AlN) Beryllia (BeO) Aluminum Silicon Carbide (AlSiC) Aluminum (Al) Copper (Cu) Polymer Ceramic Glass Epoxy (FR-4) Thermal Grease 42 16 17 244 37 26 - 2.6 476 3000 924 14 4 10 25 - 4 (3oz) 6 20 4 8.4 8 3.4 49 - 5.2 - 0.52 95 600 185 Comparative Thermal Resistances (°C/kW cm2)

122 © 2006 DCHopkinswww.DCHopkins-Associates.Com 360 102 204 635 51 1.27* Material width (mm) depth (mm) thick ( m) k (W/m °C) Si Solder Cu Al 2 O 3 Al AlSiC 10.2 12.7 15.2 10.2 12.7 15.2 * in mm 84 63 393 26 240 170 Si DBC Al 2 O 3 Al AlSiC Example Structure

123 © 2006 DCHopkinswww.DCHopkins-Associates.Com Si DBC Al 2 O 3 Al AlSiC R = (t / A) / k t = thickness, A= width x depth R, total = 0.198 °C/W *in mm 10.2 12.7 15.2 R (°C/W) layer t ( m) w(mm) D(mm) A e (mm 2 ) Si Solder Cu Al 2 O 3 Al AlSiC 360 102 203 635 51 1.27* 10.2 10.4 11.0 12.3 10.2 12.7 15.2 10.2 12.7 15.2 103 107 121 122 152 0.041 0.016 0.003 0.105 0.001 0.002 One-Dimensional Model -Using Bulk Dimensions-

124 © 2006 DCHopkinswww.DCHopkins-Associates.Com Assumption : For an isotropic material, heat flows laterally at the same rate it flows vertically. Hence: A = (W u + t)(D u + t) R = (t / A) / k Material width (mm) depth (mm) thick ( m) k (W/m °C) Si Solder Cu Al 2 O 3 Al AlSiC 10.2 12.7 15.2 10.2 12.7 15.2 360 102 204 635 51 1.27* * in mm 84 63 393 26 240 170 R = 0.232° C/W Si DBC Al 2 O 3 Al AlSiC - 45° Spreading Angle -

125 © 2006 DCHopkinswww.DCHopkins-Associates.Com Acer a2a2 a2a2 n = tan -1 (k n / k n+1 ) A n = [W n + 2t n tan ( n )] R,n = (t n / A n ) K n W > t n tan ( n ) Example Spreading Angles Composite Material Spreading Angle in * DBC* on Al 2 O 3 DBC* on BeO Cu* on Fr-4 AlSiC* on Al 85° 57° 89.8° 30° Acu Asi - Adjustable Spreading Angle - Thermal interaction of layers changes the thermal spreading angle,

126 © 2006 DCHopkinswww.DCHopkins-Associates.Com Si DBC Al 2 O 3 Al AlSiC LayerAngle (°)W(mm)D(mm)A(mm 2 )R q (°C/W) Si Solder Cu Al 2 O 3 Al AlSiC 0 86 6.2 55 30 10.2 16.0 (12.7) 12.8 13.0 14.5 10.2 16.0 (12.7) 12.8 13.0 14.5 104 --- 107 165 169 209 0.041 0.016 --- 0.003 0.148 0.001 0.036 R q = 0.290° C/W Adjusted Spreading for Structure

127 © 2006 DCHopkinswww.DCHopkins-Associates.Com Presentation Goes Off-Line We break to another topic. See supplemental material. Review of packaging paraphernalia

128 © 2006 DCHopkinswww.DCHopkins-Associates.Com Design Approaches and Tools

129 © 2006 DCHopkinswww.DCHopkins-Associates.Com In the Best of Designs... The Good the Bad and the Ugly Compliments of Celestica, Inc.

130 © 2006 DCHopkinswww.DCHopkins-Associates.Com Presentation Goes Off-Line We break to another topic. See supplemental material. Review of physical hardware Compliments of Celestica, Inc.

131 © 2006 DCHopkinswww.DCHopkins-Associates.Com Simulating Reality Our best guess at Mother Nature

132 © 2006 DCHopkinswww.DCHopkins-Associates.Com Overview on Design Tools Device Physics Component Modeling Circuit Simulation Specific Circuits Pisces, Fielday, Ansoft FEM Based Simulators Pspice, AWB, SIMetrix, Simplis SPICE based or State- Space Simulator Webench, SMS, SwitcherCAD Design Programs for Power Supplies Ease of Use Physical Level Cost $$$

133 © 2006 DCHopkinswww.DCHopkins-Associates.Com FEM Design Tools Pisces and Fielday, IBM tools, simulate semiconductor devices at the electron level Ansoft simulator models electro- magnetic devices with FEM –On the right is a gapped ferrite core showing the flux lines Expensive and require significant learning See additional Ansoft foils

134 © 2006 DCHopkinswww.DCHopkins-Associates.Com SPICE Design Tools Pspice 1, AWB 1 and SIMetrix 2 use time differential s for solving circuits. Good for modeling electrical circuits Transistor and op-amps are modeled as equivalent circuit s On the right is a simple circuit and waveform from Pspice Easy to use but requires circuit design experience and $$$ 1=Cadence, 2=Simetrix inc

135 © 2006 DCHopkinswww.DCHopkins-Associates.Com SPICE Design Tools - Limitations Need to simulate long times to look at control loop behavior in milliseconds, yet... SPICE will calculate in nanoseconds because of the time domain calculations One solution is to use Average Models, where the switching waveform is averaged out. Models require mathematical definitions and a good understanding of the subject When simulating switchmode supplies, SPICE has limitation

136 © 2006 DCHopkinswww.DCHopkins-Associates.Com State-Space Design Tools Another solution is to use a state-space simulator such as Simplis 1 Simplis calculates based on the topology and only at the switching points Simulation speed for switchmode power supplies is improved up to 100X You can enter the circuit as is 1=Transim Corp

137 © 2006 DCHopkinswww.DCHopkins-Associates.Com Webench Design Tool - www.webench.com Webench is a design tool from National Semi. in conjunction with Transim Corp. Webench helps you pick the IC, simulate and build. Within Webench is Websim which uses Simplis as the simulation engine Webench is a Web based tool Very easy to use and free but not flexible

138 © 2006 DCHopkinswww.DCHopkins-Associates.Com SMS Design Tool The program –helps the user select the appropriate controller IC –designs and selects components –easy to use but not flexible –free Great for the novice that needs a quick power supply design Switcher Made Simple (SMS) is a PC program from National Semi., in conjunction with Transim Corp

139 © 2006 DCHopkinswww.DCHopkins-Associates.Com Input Filtering (Not selective hearing)

140 © 2006 DCHopkinswww.DCHopkins-Associates.Com Input Filter Why is an input filter needed ? –Reduce ripple current from the PS –Prevent filter oscillation –Reduce the di/dt of the load reflected back to the input

141 © 2006 DCHopkinswww.DCHopkins-Associates.Com Input Filter Ideally, Iin should be a clean DC current There will be the ripple current, Irip, from the PS switching stage To reduce the input ripple, use an L-C network on the front-end of the power supply The resonant frequency << Fsw Irip Iin Time –Reduce ripple current from the PS –Prevent filter oscillation –Reduce the di/dt of the load reflected back to the input Why is an input filter needed ?

142 © 2006 DCHopkinswww.DCHopkins-Associates.Com Input Filter If the resonance of L1,C1 is around Fsw of the PS, a large amount of current can oscillate between L1 and C1 The amount of current depends on the Q of L1 and C1 Very common if L1 is just the board trace between the PS and the Vin source This oscillation can depend on the length of board trace! Adding an inductor will lower the resonance and make this parameter controllable If the resonance of L1 and C1 still a problem, dampen it with an R-C across L1 or use lossy core material for L1

143 © 2006 DCHopkinswww.DCHopkins-Associates.Com Input Filter Another problem arises if L1 and C1 have a large Q Even if the resonance is less than Fsw, this peaking effect can cause problems with the control loop This resonant frequency can show up on the output of the power supply Again, solutions are either an R-C across L1 or use a lossy core material for L1

144 © 2006 DCHopkinswww.DCHopkins-Associates.Com Input Filter Another characteristic is reduction of input di/dt during load transients –Problems caused in the Vin bus Ringing on the board traces Vin not able to respond to load change Solution: absorb the load energy –How? Large cap on Vin bus – PTH parts on SMT board? No Adding more output caps to absorb the energy? Expensive - No Add second stage filter? Inexpensive SMT parts - Yes –First filter L1,C1 filters the high-frequency switching components. Second filter L2,C2 is a low-pass filter to smooth out the reflected load transient

145 © 2006 DCHopkinswww.DCHopkins-Associates.Com Input Filter Shown is a two-stage filter with input current and load current Beware of inter-stage oscillations

146 © 2006 DCHopkinswww.DCHopkins-Associates.Com A Different Approach to a DESIGN Optimally Selecting Packaging Technologies and Circuit Partitions Based on Cost and Performance APEC 2000 Conference John B. Jacobsen and Douglas C. Hopkins

147 © 2006 DCHopkinswww.DCHopkins-Associates.Com Full-Cost Model Other OH Depreciation Wages Packaging materials Materials Cost Packaging Materials & Production Costs (controllable) Minimum packaged Comp. packaging components Overhead Standard unit cost Materials Cost Production Cost

148 © 2006 DCHopkinswww.DCHopkins-Associates.Com Centers of Cost Materials cost* Production cost* –*Full Cost Partitioning cost Product business cost (return on investment for development of one product) Company business cost (return on investment for cross products)

149 © 2006 DCHopkinswww.DCHopkins-Associates.Com Centers of Cost (cond) Materials cost represent direct costs of packaging materials. Production cost includes factors for wages and product volume, but are independent of material costs. Partitioning cost is incurred for each technology used. Full cost combines material costs and production costs. Product business cost, i.e. return on investment for development of one product, is an investment in future payback. The total cash flow from development until end of production determines the business costs for a product. continued

150 © 2006 DCHopkinswww.DCHopkins-Associates.Com Centers of Cost (cond) Company business cost, i.e. return on investment for cross- product usage, reflects the cost of sub-optimization within one single product. –Reusing the same packaging technologies, designs (diagrams) and even physical circuits (building blocks) across different products should be measured at the company level. The value of building blocks becomes obvious through savings in repetitive development costs and maintenance of function

151 © 2006 DCHopkinswww.DCHopkins-Associates.Com Production Cost Dependency by Volume 10k32k100k320k1000k Products/Year 0% 100% 200% 300% 400% 500% 600% 700% Production Cost Other overhead costs Depreciation Wages yr - 2000

152 © 2006 DCHopkinswww.DCHopkins-Associates.Com Cost Variation Within a Technology 051015202530 Surface Density Relative Cost 0 0.2 0.4 0.6 0.8 1 Packaging & Production Costs Packaging Performance: (electrical, thermal, mechanical TF module & leadframe FR4 Changing technology to change density Functional integration within technology 110 SMDs 14 leadet 70 SMDs 7 leadet

153 © 2006 DCHopkinswww.DCHopkins-Associates.Com Relative Cost of Technologies 051015202530 Surface Density Relative Cost 0 0.2 0.4 0.6 0.8 1 DBC Packaging & Production Costs Packaging Performance: electrical, thermal, mechanical TF & Plated Cu IMS FR4 Hot Embossing Performance Circuit cost by change in technology

154 © 2006 DCHopkinswww.DCHopkins-Associates.Com Relative Packaging & Production Cost Hot Embossing FR4 Cu( 2x35um) FR4 Cu( 4 layer ) IMS (1 layer on Al) TTF DBC( 0,63 Al2O3 ) Z-strate Cu( 2 layer) TF multilayer Substrate Technology 0 2 4 6 8 10 12 14 Relative Cost Substr/in 2 leaded auto/10 comp SMD/10 comp Power chip& wire/10 comp Integrated res/10 comp Relative to 1 in 2 of FR4 a b c d d a b d c

155 © 2006 DCHopkinswww.DCHopkins-Associates.Com Relative Production Cost per Technology Leaded-manualLeaded-autoPower chip & wireSMD-auto Assembly Technology 0% 20% 40% 60% 80% 100% 120% Cost/component

156 © 2006 DCHopkinswww.DCHopkins-Associates.Com THE END Thank you for your interest in DCHopkins & Associates www.DCHopkins-Associates.Com


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