Present and Uppgcoming Issues in Power … to MICS?action...Energy Harvesting • Y. K. Ramadass, et...

Present and Upcoming Issues p gin Power Management IC Research

[LED Driver & Portable Power]

[NAME REMOVED][NAME REMOVED]

Contents

• Power Management Research Areash• Current Research Issues

– Digital DC-DC Converter– LED Driver

• Upcoming Research Issuesp g– Wireless Power– Energy Harvesting gy g

• Conclusions• Reference• Reference• Appendix

Power Management Research Topics

Power Management

Power Supply Display AudioMotor

Portable Power

Line Power

OLED Driver

LED Driver Power Power

Battery C l

DC-DCWireless P

Energy H i

DriverDriver

LED BLU

LED Li h i Ctrl.

DC DC

SC SMPS LDO

Power HarvestingBLUsLighting

SC SMPS LDO

Analog DigitalAnalogCtrl.

DigitalCtrl.

Contents





DC-DC Converter

• TopologyL D O t t(LDO)– Low Drop Output(LDO)

• Low noise, No magnetics• Poor efficiency No step up• Poor efficiency, No step-up

– Switched Capacitor(SC) DC-DC converter• No magnetics Step-up possibleNo magnetics, Step up possible• High loss and noise

– Switching Mode(SM) DC-DC converterg ( )• High efficiency, Step-up possible• Monolithic inductor, High noise

Switching Mode DC-DC converter

• Conventional SM DC-DC Converter

[“Comparative Studies of Common Control Schemes for Reference

<Voltage Mode> <Current Mode>

• Requirements– Decrease weight and size

[ Comparative Studies of Common Control Schemes for Reference Tracking and Application of End-point Prediction,” CICC 2007]

g– High efficiency– Fast transient response, Low output ripple, ...Fast transient response, Low output ripple, ...– Digital power management

Digital Power Management

• Analog vs. Digital A l B k C t ll– Analog Buck Controller

– Digital Buck Controllerg

[“A Robust Digital DC-DC Converter with Rail-to-Rail Output Range in 40nm CMOS,” ISSCC 2010]


• BenefitsR d d t t– Reduced component count

– Adaptive Controlbili– Programmability, Better reuse, etc.

[“Digital Power for Wireless Infrastructure Applications,” APEC 2010 Special Presentations]

<Analog Implementation> <Digital Implementation>


• Obstacles ADC d i– ADC design

• Power consumption, Resolution, Area, …

Digital Compensator Design– Digital Compensator Design• Cost, Complexity, …

DPWM design– DPWM design• Speed, Resolutions, ….

– System cost reductionSystem cost reduction– User friendly interface


• Solutions

O i i d ADC ( Wi d d ADC D l li ADC)

[“High-frequency digital PWM controller IC for DC-DC converters,” TPE 2003]

– Optimized ADC (e.g. Windowed ADC, Delay-line ADC)– Look up table– Clever DPWMs (e.g. Dithering, Hybrid DPWM)


• Current Status

Inventors2.5 %

Early Adopters13 5 %

Early Majority

34 %

Late Majority

34 %

Laggards16 %

13.5 % 34 % 34 %

[“Digital Power After the Hype,” APEC 2010]

Contents





LED Driver

• Typical Full LED BLUs Architecture

– LED control interface (ex. I2C, SPI)– Uniform light distribution (Current mismatch)

LED forward voltage(V ) compensation– LED forward voltage(VF) compensation– DC power supply for LED strings (Buck, Boost)

VF Compensation Circuit

• Compensation Circuit Requirements

– The lowest voltage channel detection Feedback signal generation– Feedback signal generation


• Previous Approaches (1)Wi d OR [U S t t US 2004/6690146 B2]– Wired OR [U.S. patent: US 2004/6690146 B2]

• Advantage: Easy to implementationAdvantage: Easy to implementation• Disadvantage: Inaccuracy, Use External Components


• Previous Approaches (2)OP AMP f h h l [AMS D t Sh t AS3691]– OP-AMP for each channel [AMS Data Sheet: AS3691]

• Advantage: More accurate than Wired-OR methodAdvantage: More accurate than Wired OR method• Disadvantage: Consume large layout area


• Previous Approaches (3)S F ll & OTA [S H ISSCC 2010]– Source Followers & OTA [S. Hong, ISSCC 2010]

• Advantage: Use only one OTA• Disadvantage: Static current consumption


• Proposed VF Compensation CircuitShift R i t [EPE 2009 El t L tt ]– Shift Register [EPE 2009, Electron. Lett.]

– Vsen 〈 Vref : Vcmp (H) Vout↑ Vsen↑– Vsen 〉 Vref : Vcmp (L) Vout↓ Vsen↓


• Timing Diagram

– Vcmp = “L”: Shift register clock keeps runningVcmp L : Shift register clock keeps running– Vcmp = “H”: Holding shift register clock


• Measurement ResultsV 1 2 V I 40 A– Vref = 1.2 V, ILED= 40mA


• VOUT Compensation Results

41 7

ΔV=0.6 V41 4

41.7

T[V

]

41.4

VO

UT

0 10 20 30 40 50 60

41.1

– ΔVOUT = 0.6 V

Time [minutes]

– Power Saving = 192 mW


• Future Works

– Integrate VF compensation circuits– Design Digital DC-DC converter

Contents





Wireless Power

• ApplicationsWi l h i– Wireless charging

– RFIDi di l i l– Biomedical implants

[“Qi Wireless Power Consortium,” CES 2009] [“Retinal Prosthesis,” ISSCC 2004]

Wireless Power

• RF: Low power level(< 1 W), Far-field

• Inductive: Wide range power level, Near-feild

[“Power Management System for Online Low Power RF Energy Harvesting Optimization,” TCAS-I]

[“An Efficiency-Enhanced CMOS Rectifier With Unbalanced-Biased Comparators for Transcutaneous-Powered High-Current Implants,” JSSC 2009]

Wireless Power

• Wireless Battery Charging System OverviewB St ti– Base Station

• Transmit power to reciever

Mobile Device– Mobile Device• Provide control information to transmitter

[“Qi Making Wireless Power Work,” APEC 2010 Special Presentations]

Wireless Power

• ChallengesC t & F F t– Cost & Form Factor

– Interoperabilityffi i i– Efficiency vs. Distance

– Industry Standard …

• Research Issues– AntennaAntenna

• Form factor reduction, Adaptive matching

– Rectifier• Efficiency, Low voltage operation

– Power Management• Efficiency

Wireless Power

• OppertunitiesS t t i th k t h l i– Smart power management is the key technology in wireless power and charging.Wireless bettary charging standard will be released– Wireless bettary charging standard will be released. Therefore, there are many things to realize the system.

[“Design Solutions for a Multi-Object Wireless Power Transmission Sheet Based on Plastic Switches,” ISSCC2006]

Contents





Energy Harvesting

• ApplicationsS N t k– Sensor Network

– Medical Measurement or MonitoringS lf d li i– Self-Powered Application

[“An Efficient Piezoelectric Energy Harvesting Interface Circuit Using a Bias-Flip Rectifier and Shared Inductor,” ISSCC 2009]

Energy Harvesting

• ChallengesV i bl i t d h t i ti– Variable input power and characteristics

– Low input power ffi i– Efficiency

[“Low Power Energy Harvesting Making the Difference with Energy Efficient Power Management,” APEC 2009]

Energy Harvesting

• Research IssuesZ t t– Zero-energy start-up

– Improved efficiencyC d C i– AC and DC input management

– Higher conversion ratio

[http://www.popsci.com/content/human-generator]

Contents



• Upcoming Research Issuesp g– Wireless Power– Energy Harvestinggy g


Conclusions

• Current Research TopicS t Di it l DC DC C t D i– Smart Digital DC-DC Converter Design

– LED Driver with Digital DC-DC Converter Design

• Upcoming Research Topic– Wireless Power

• Wireless battery charging system realization

E H ti– Energy Harvesting• Energy harvesting system feasibility verification

Conclusions

• Conventional PMICs still need to improve PMIC fperformance.

• PMIC plays an important role in emerging devices and applications.

• Cost, Efficiency and Reliability are key factors in , y y yPMIC research & development.

• There are many opportunities in PMIC research !There are many opportunities in PMIC research !

References Power Management• B. K. Bose, “The Past, Present and Future of Power Electronics,” IEEE Industrial Electronics Magazine, pp. 1-5, Jun.

2009.• T. R. Efland, “The Earth is Mobile - Power”, ISPSD 2003, pp. 2-9, Apr. 2003.• M. Manninger, “Power Management for Portable Devices”, ESSCIRC 2007, pp. 167-173, 2007.• G. A. Rincon-Mora, “A Low-Voltage, Low Quiescent Current, Low Drop-Out Regulator,” JSSC, pp. 36-44, 1998.• Y. Wu, et al., “Comparative Studies of Common Control Schemes for Reference Tracking and Application of End-point p g pp p

Prediction,” CICC 2007, pp. 559-562.• P. Hazucha, et al.“A 233-MHz 80%–87% Efficient Four-Phase DC–DC Converter Utilizing Air-Core Inductors on

Package,” JSSC. Vol. 40, pp. 838-845, 2005• B. Shaffer, “Internal Compensation – Boon or Bane?” Unitrode Design Seminar SEM 1400, TI, Dallas, TX, 2001.• J. Y. Ryoo, “DC-DC Converter Design,” IDEC lecture note, 2008.• A. Hande, “Power Converter Circuits,” UTD presentation, 2006.Digital Power Management• D. Maksimović, et al., “Impact of digital control in power electronics,” Proc. IEEE Int. Symp. PSDI, 2004, pp. 13 – 22. • B. J. Patella, et al., “High Frequency Digital PWM Controller IC for DC-DC Converters,” IEEE Trans. on Power

Electronics, Vol. 18, No. 1, Part II, 2003.• A. P. Dancy, et al., “High-Efficiency Multiple-Output DC-DC Conversion for Low-Voltage Systems,” IEEE Trans. on VLSI

Systems, Vol. 8, No. 3, pp. 252-263, 2000.h l “Q i i l i d i i C li i i i ll C ll d C ” l• A. V. Peterchev, et al., “Quantization Resolution and Limit Cycling in Digitally Controlled PWM Converters,” TPE., vol.

18, pp. 301-308.• P. T. Krein, “Digital Control Generations—Digital Controls for Power Electronics through the Third Generation,” PEDS

2007.• R V White “Digital Power After the Hype” APEC 2010 Special Presentaions• R. V. White, Digital Power After the Hype, APEC 2010 Special Presentaions.• C. Young, “Digital Power for Wireless Infrastructure Applications,” APEC 2010 Special Presentations

ReferencesLED Drive• E. Kang, et al., “A new low voltage detecting method for multi-string LED BLU circuit,” EPE 2009.• E. Kang, et al., “Sequential Low Voltage Detecting Method for Multi-string LED BLU Circuit,” Electron. Lett., Issue 12,

2010. • S. Hong, et al., “A Double-Loop Control LED Backlight Driver IC for Medium-Sized LCDs,” ISSCC 2010, pp. 116 – 117.• S. Ohr, “The Promise of LED Backlights in Consumer TVs,” APEC 2010 Special Presentations. Wireless Power• S O’Driscoll et al “A mm Sized Implantable Power Receiver with Adaptive Link Compensation” ISSCC 2009 pp 294• S. O Driscoll, et al., A mm-Sized Implantable Power Receiver with Adaptive Link Compensation, ISSCC 2009, pp. 294-

295.• Jun Yi, et al., “Dual-Power-Path RF-DC Multi-Output Power Management Unit for RFID Tags,” VLSI 2009, pp. 200-201.• Wentai Liu, et al., “Retinal Prosthesis,” ISSCC 2004, pp. 219-219.• R. Sanderson, “The Growth Potential for Wireless Power & Charging,” APEC 2010 Special Presentaions. g g p• S. Terry, “Qi Making Wireless Power Work,” APEC 2010 Special Presentations.Energy Harvesting• Y. K. Ramadass, et al., “An Efficient Piezoelectric Energy Harvesting Interface Circuit Using a Bias-Flip Rectifier and

Shared Inductor,” ISSCC 2009Z R “L P E H ti M ki th Diff ith E Effi i t P M t” APEC• Z. Regan, “Low Power Energy Harvesting Making the Difference with Energy Efficient Power Management,” APEC 2009 Special Presentations.

• A. Dolgov, et al., “Power Management System for Online Low Power RF Energy Harvesting Optimization,” TCAS-I.(early access)

Useful Links• http://ecee.colorado.edu/copec/index.php• http://www-power.eecs.berkeley.edu/index.html• http://circuit.kaist.ac.kr/• http://users.ece.gatech.edu/~rincon/

h // 2 i d / i dl/• http://www2.engr.arizona.edu/~isdl/• http://www.wirelesspowerconsortium.com/• http://www.powersoc.org/index.php

Thank you for listening !y g

Appendix

General DC-DC Converter R h T dResearch Trends

Switching Mode

• Decrease weight and sizeF t ti DC DC t– Fast operation DC-DC converter

• Smaller Passive Component • Higher Dynamic loss (Switching loss)• Higher Dynamic loss (Switching loss)

– Passive Component Integration• Compensation or filter passives integrationCompensation or filter passives integration• Stability, Low Q factor, Optional process

– Single inductor multi-output converterg p• System cost reduction• Efficiency reduction, Strict Regulation

Switching Mode

• High Efficiency Li ht l d ffi i i t ( PFM)– Light load efficiency improvement (e.g. PFM)

– Charge recycling

• Fast Transient Response, Low output ripple, ...– V2 controller– Hysteretic controller– Multi-phase controller

Switched Capacitor

• Multi-phase low noise converteri h ffi i• High efficiency SC converter

• Hybrid SC convertery

Present and Uppgcoming Issues in Power … to MICS?action...Energy Harvesting • Y. K. Ramadass, et...

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