CS 150 - Spring 2007 – Lec #28 – Power - 1Power! Motivation for design constraints of power consumption! Power metrics! Power consumption analysis in CMOS! How can a logic designer control power?CS 150 - Spring 2007 – Lec #28 – Power - 2Automobiles700 MillionTelephones4 BillionElectronic Chips60 BillionX-Internet“X-Internet” Beyond the PCForrester Research, May 2001Revised 2007500Million1.5 BillionInternet ComputersInternet UsersToday’s InternetCS 150 - Spring 2007 – Lec #28 – Power - 3“X-Internet” Beyond the PCForrester Research, May 2001MillionsYearXInternetPCInternetCS 150 - Spring 2007 – Lec #28 – Power - 4Cell PhonesSiemens SL45iEricsson T68! Phone w/voice command,voice dialing, intelligenttext for short msgs! MP3 player + headset,digital voice recorder! “Mobile Internet” with abuilt-in WAP Browser! Java-enabled, over the airprogrammable! Bluetooth + GPRS! Enhanced displays +embedded camerasCS 150 - Spring 2007 – Lec #28 – Power - 5Shape of Things! Phone + Messenger + PDA Combinations" E.g., Blackberry 5810 Wireless Phone/Handheld# Integration of PDA + Telephone# PLUS Gateway to Internet and Enterprise applications# 1900 MHz GSM/GPRS (Euroversion at 900 Mhz)# SMS Messaging, Internet access# QWERTY Keyboard, 20 line display# JAVA applications capable# 8 MB flash + 1 MB SRAMCS 150 - Spring 2007 – Lec #28 – Power - 6Shape of Things to Come! Danger “Hiptop”" Full-featured mobile phone w/Internet Access" Email + attachments/instant messaging + PIM" Digital camera accessory" End-to-end integration of voice + data apps" Media-rich UI for graphics + sound" Large screen + QWERTY keyboard" Data nav: keyboard or push wheel" Affordable (under $200)" MIDI synthesizer for quality sound" Multi-tasking of user actions" Customizable ring tones and alertsto personalize hiptop experienceCS 150 - Spring 2007 – Lec #28 – Power - 7Important (Wireless)Technology Trends“Spectral Efficiency”:More bits/m3Rapidly decliningsystem costRapidly increasingtransistor densityCS 150 - Spring 2007 – Lec #28 – Power - 8In the Physical World: Sensor DevicesCS 150 - Spring 2007 – Lec #28 – Power - 9Important (Wireless)Technology TrendsSpeed-Distance-CostTradeoffsRapid Growth: Machine-to-Machine Devices (mostly sensors)CS 150 - Spring 2007 – Lec #28 – Power - 10Why Worry About Power?! Portable devices:" Handhelds, laptops, phones, MP3 players, cameras, … all need to run forextended periods on small batteries without recharging" Devices that need regular recharging or large heavy batteries will lose out tothose that don’t.! Power consumption important even in “tethered” devices" System cost tracks power consumption:# Power supplies, distribution, heat removal" Power conservation, environmental concerns! In 10 years, have gone from minimal consideration of power consumptionto (designing with power consumption as a primary design constraint!CS 150 - Spring 2007 – Lec #28 – Power - 11! Power supply provides energy for charging and discharging wires andtransistor gates. The energy supplied is stored & then dissipated asheat.! If a differential amount of charge dq is given a differential increasein energy dw, the potential of the charge is increased by:! By definition of current:dqdwV /=dtdqI /=dtdwP /!Power: Rate of work being done wrt timeRate of energy being usedIVPdtdqdqdwdtdw !==!=/!"#=tPdtwtotal energyUnits:tEP !=Watts = Joules/secondsA very practical formulation!If we would liketo know total energyBasicsCS 150 - Spring 2007 – Lec #28 – Power - 12Basics! Warning! In everyday language, the term “power” isused incorrectly in place of “energy”! Power is not energy! Power is not something you can run out of! Power can not be lost or used up! It is not a thing, it is merely a rate! It can not be put into a battery any more thanvelocity can be put in the gas tank of a carCS 150 - Spring 2007 – Lec #28 – Power - 13+1V-1 OhmResistor1A0.24 Calories per SecondHeats 1 gram of water0.24 degree CThis is how electric tea pots work ...1 Joule of HeatEnergy per Second1 Watt20 W rating: Maximum powerthe package is able to transferto the air. Exceed rating andresistor burns.CS 150 - Spring 2007 – Lec #28 – Power - 14Cooling an iPod nano ...Like a resistor, iPod relieson passive transfer of heatfrom case to the airWhy? Users don’t wantfans in their pocket ...To stay “cool to the touch” via passive cooling,power budget of 5 WIf iPod nano used 5W all the time, its battery would last15 minutes ...CS 150 - Spring 2007 – Lec #28 – Power - 15Powering an iPod nano (2005 edition)Battery has 1.2 W-hourrating: Can supply1.2 W of power for 1 hour1.2 W / 5 W = 15 minutesReal specs for iPod nano :14 hours for music,4 hours for slide shows85 mW for music300 mW for slidesMore W-hours require bigger batteryand thus bigger “form factor” --it wouldn’t be “nano” anymore!CS 150 - Spring 2007 – Lec #28 – Power - 160.55 ounces12 hourbattery life$79.001 GBCS 150 - Spring 2007 – Lec #28 – Power - 1712 hourbattery life24 hourbattery lifefor audio5 hourbattery lifefor photos20 hour battery life for audio,6.5 hours for movies (80GB version)Up from 14hours for 2005iPod nanoUp from 4hours for 2005iPod nanoThinner than 2005 iPod nanoCS 150 - Spring 2007 – Lec #28 – Power - 18Notebooks ... now most of the PC marketPerformance: Must be “close enough” to desktopperformance ... many people no longer own a desktopHeat: No longer “laptops” -- top may get “warm”,bottom “hot”. Quiet fans OKSize and Weight: Ideal: paper notebook1 in8.9 in12.8 inApple MacBook -- Weighs 5.2 lbsCS 150 - Spring 2007 – Lec #28 – Power - 19Battery: Set by size and weight limits ...Almost full 1 inchdepth. Width andheight set by availablespace, weight.Battery rating:55 W-hourAt 2.3 GHz,Intel Core DuoCPU consumes 31W running aheavy load -under 2 hoursbattery life! And,just for CPU!At 1 GHz, CPU consumes13 Watts. “Energy saver”option uses this mode ...46x energy than iPod nano.iPod lets you listen to musicfor 14 hours!CS 150 - Spring 2007 – Lec #28 – Power - 20Battery Technology! Battery technology has developed slowly! Li-Ion and NiMh still the dominate technologies! Batteries still contribute significantly to the weightof mobile devicesToshiba Portege3110 laptop - 20%HandspringPDA - 10%Nokia 61xx -33%CS 150 - Spring 2007 – Lec #28 – Power - 2155 W-hour batterystores the energy of1/2 a stick
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