Best of Best at Buy, these are last minute sale

Week 4 Feb 2009 Lenovo Promotions

This weeks promotions running February 24 through March 2 are labeled Week A.

This week’s product focus is on the T400 and T500 Notebooks. There will also be a 72 Hour sale that begins Wednesday, Feb 25 and runs until Friday, Feb 27. There are ecoupons available for both promotions to offer greater discounts

Latest Promotions:


72 Hour Sale ( Feb 25-27)

  • Promotional Copy: Save up to an additional 20% on select products. 16% off ThinkPad X61s, X301, X200,X200s,X200 Tablet, W500, W700, W700ds, 10% off monitors, and 20% off Lenovo branded accessories
  • ecoupon: CAP72HOURSALE
  • Week A promo 1
  • Lenovo 72 Hour Sale! Use ecoupon: CAP72HOURSALE to get up to an additional 20% off sale price From Feb 25-27

Lenovo 72 Hour Sale! Use ecoupon: CAP72HOURSALE to get up to an additional 20% off sale price From Feb 25-27

Deal of the Week: 10% off T400 and T500 (Feb 24- Mar 2)

  • Promotional Copy: Save an additional 10% on T400 and T500 Notebooks and 15% on Warranty Upgrades
  • ecoupon: CAPTSERIESDOW
  • Week A promo 2
  • Save an additional 10% on Lenovo -T400 and T500 -use ecoupon: CAPTSERIESDOW from Feb 24- Mar 2

Save an additional 10% on Lenovo -T400 and T500 -use ecoupon: CAPTSERIESDOW from Feb 24- Mar 2

Save up to an additional 15% off select ThinkPads ( Feb 24- Mar 2)

  • Promotional Copy: Use ecoupon: CAPSAVEMORENOW to get up to an additional savings of 15%. 10% off ThinkPad X301,X200, T400, T500, R400, R500, W500, ThinkCentre A62 and 15% off X61s
  • ecoupon: CAPSAVEMORENOW  
  • Week B promo 3
  • Save an extra 10% off sale price on Lenovo ThinkPads from Feb 24- Mar 2 use code: CAPSAVEMORENOW

Save an extra 10% off sale price on Lenovo ThinkPads from Feb 24- Mar 2 use code: CAPSAVEMORENOW

Options Promo: ( Feb 24- Mar 2)

  • Promotion Type: % off Select Options
  • Select Docking Stations: additional 12% off web price
  • Select Keyboard and Mice: additional 10% off web price
  • Week B promo 4
  • Save up to12% on select Lenovo accessories

Save up to12% on select Lenovo accessories

Ongoing Promotions:

Save additional on ThinkPad notebooks (Ends March 31)

  • Promo Copy: Save up to an additional 10% off ThinkPad notebooks over $1000 and 15% off ThinkPad notebooks over $1600. WARRANTY UPGRADE MUST BE INCLUDED IN CART (system and warranty must be 1 for 1 to receive discount). (excludes X200s, X200 Tablet, X301, W700)
  • ecoupon: CATQ409CLOSEMORE
  • Click here for more Lenovo ecoupons

 Click here for more Lenovo ecoupons

Save additional on ThinkPad notebooks and ThinkCentre A Series desktops (Ends March 31)

  • Promo Copy: 10% on cart totals of $1200+ and 15% off cart totals of $2000+ (discount is based on system price only). Available for current calls only. ThinkPad notebooks and ThinkCentre A Series desktops (excludes X200s, X200 Tablet, X301, W700, A61e)
  • ecoupon: CATQ409CLOSENOW
  • Click here for more Lenovo ecoupons
    Click here for more Lenovo ecoupons

    Save additional on ThinkPad notebooks and ThinkCentre A Series desktops (Ends March 31)

    • Promo Copy: Use ecoupon to get a 5% additional off on ThinkPad notebooks and ThinkCentre desktops (excludes X200s, X200 Tablet, X301, W700, A61e)
    • ecoupon: CATCLOSE4Q5
    • Click here for more Lenovo ecoupons
  • Click here for more Lenovo ecoupons

    Buy cell phones online

    Who are the Cell Phone Shop?

    The Cell Phone Shop has a great selection of low cost cell phone accessories. They carry PDA cases, headsets, chargers, and cases for all the major carriers and models. They offer up to an 80% discount on retail prices on theirr accessories compatible with: iPhone, Blackberry, Motorola RAZR, TMobile Sidekick, Palm Treo, LG Chocolat. They also offer digital camera batteries and memory cards at an unbeatable price. They guarantee their customers the lowest price on the Internet. In addition to matching the lowest price from the web, they will deduct an extra 10% from your order on the original price discrepancy. Free shipping coupon is available, click on any of desired banner for more details:


    Free shipping coupon

    BlueTooth 80% off.

    Cell phone desktop charger as low as $12.99.


    cell phone accessories 80% off

    New York Times Best Sellers and this week’s great deals

    Tax Center, New York Times Best Sellers and this week’s great deals

    It’s Tax Time! Check the Buy.com Tax Center for low prices on top selling tax software, books, calculators and more! Find everything your customers need to get their taxes done early this year at one convenient location


    Tax Software at Buy.com

    Text Link – Save 50% Off New York Times Best Sellers! exp 12/31/09

    The Associate (Hardcover)
    Eligible for FREE SHIPPING
    List Price: $27.95
    Save: $11.05
    Buy.com Price: $21.15

    Run for Your Life (Hardcover)
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    Buy.com Price: $21.03

    Bone Crossed: A Mercy Thompson Novel (Hardcover)
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    List Price: $24.95
    Save: $9.99
    Buy.com Price: $19.21

    Hot Video Games!

    Street Fighter IV (XBOX)
    FREE SHIPPING
    Buy.com price: $58.99

    The Sims 3 (Collector’s Edition)
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    Buy.com Price: $68.99

    F.E.A.R. 2: Project Origin (XboX)
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    List Price: $59.99
    Save: $4.00
    Buy.com Price: $55.99

    Magnavox Keychain Digital Camera DigiClam MIC4011NB/27 – Assorted Colors    
    FREE BUDGET SHIPPING  
    List price: $29.99
    SAVE $22.00
    Buy.com price: $7.99
     

    Disney 3MP Digital Camera – Pix Max Pirates of the Caribbean, DS12001      
    FREE BUDGET SHIPPING
    List price: $79.99   
    SAVE $60.00
    Buy.com price: $19.99
     

    IBM ThinkPad T43 Notebook, Intel Pentium 730(1.6GHz), 512MB RAM, 40GB HDD, 14.1” XGA(1024×768) TFTLCD, Intel900, 8x DVD, Intel 802.11abg Wireless(MPCI), Modem(CDC), 1Gb Ethernet(LOM), Windows XP Pro, Refurbished        
    FREE BUDGET SHIPPING 
    List price: $799.99 
    SAVE $510.00
    Buy.com price: $289.99

    Imation Apollo 160GB USB 2.0 Portable Hard Drive   
    FREE BUDGET SHIPPING    
    List price: $126.64
    SAVE $78.65
    Buy.com price: $47.99

    Kingston 4GB USB 2.0 DataTraveler I Gen 2 – Yellow    
    FREE BUDGET SHIPPING     
    Buy.com price: $11.29    

    Seagate FreeAgent XTreme 1TB USB 2.0/eSATA/FireWire 400 External Hard Drive    
    FREE BUDGET SHIPPING 
    List price: $179.99  
    SAVE $48.00
    Buy.com price: $131.99

    Logitech Harmony 659 Remote – Refurbished  
    FREE BUDGET SHIPPING      
    Buy.com price: $49.99    

    Kingston 8GB Secure Digital High Capacity (SDHC) Card – Class 4
    FREE BUDGET SHIPPING     
    Buy.com price: $14.99     

    Xbox 360 Wireless Network Adapter    
    FREE BUDGET SHIPPING 
    List price: $99.99 
    SAVE $30.00
    Buy.com price: $69.99
    *(Limited Stock)

    SanDisk 8GB Cruzer Micro U3 USB2.0 Flash Drive   
    FREE BUDGET SHIPPING      
    List price: $57.99 
    Buy.com price: Special price

     

    Motorola H15 Bluetooth Headset – New OEM in Poly-Bag    
    FREE BUDGET SHIPPING 
    List price: $159.95    
    SAVE $99.96
    Buy.com price: $59.99

    TRENDnet TEW-672GR 300Mbps Dual Band Wireless N Gigabit Router    
    FREE BUDGET SHIPPING     
    List price: $179.99 
    Buy.com price: $98.99  
    $20.00 Mail-in Rebate    
    $78.99 After Rebate

    Top Seller
    Western Digital 1TB My Book Essential USB 2.0 External Hard Drive        
    FREE BUDGET SHIPPING 
    List price: $149.99  
    SAVE $50.00
    Buy.com price: $99.99

    Belkin Laptop Cooling Pad – White  
    List price: $39.99  
    Buy.com price: Special price



    Kingston 4GB Secure Digital High Capacity Card – Class 4    
    FREE BUDGET SHIPPING        
    Buy.com price: $9.48    

    Intel Pentium Dual-Core E5200 – BX80571E5200      
    FREE BUDGET SHIPPING            
    Buy.com price: $64.99
    *(Expires 2/17/09)             


    Belkin TuneBase FM Transmitter    
    FREE BUDGET SHIPPING 
     List price: $114.99 
    Buy.com price: $68.99
    $20.00 Mail-in Rebate    
    $48.99 After Rebate

    Netgear ReadyNAS NV+ 1TB Gigabit Desktop Network Storage (2×500GB)     
    FREE BUDGET SHIPPING      
    Buy.com price: $639.99    



    17″ A170E1-08 LCD Monitor w/ Speakers – Black    
    FREE BUDGET SHIPPING 
    List price: $99.99  
    SAVE $17.00
    Buy.com price: $82.99
    Ships from and sold by Geeks

    OCZ Neural Impulse Actuator – Brain Mouse   
    FREE BUDGET SHIPPING      
    Buy.com price: $119.99
    $40.00 Mail-in Rebate  
    $79.99 After Rebate

    Lexmark X6650 Wireless All-In-One Color Inkjet Printer
    FREE BUDGET SHIPPING 
    List price: $129.99
    SAVE $50.00
    Buy.com price: $79.99

    Cables Unlimited Super Laptop Cooler w/ 3-port USB 2.0 And Card Reader, 2 Fan(s), 1600rpm, Sleeve Bearing – Aluminum   
    FREE BUDGET SHIPPING 
    List price: $59.99  
    Buy.com price: $25.99 
    $10.00 Mail-in Rebate    
    $15.99 After Rebate

    Mavis Beacon Teaches Typing Deluxe V 20    
    FREE BUDGET SHIPPING 
    List price: $19.99
    Buy.com price: $17.99
    $10.00 Mail-in Rebate      
    $7.99 After Rebate

    Nintendo Wii Wireless Gamepad Controller by Thrustmaster    
    FREE BUDGET SHIPPING      
    Buy.com price: $16.99

    Brother PT-1010 Portable Handheld Home and Office Labeler    
    FREE BUDGET SHIPPING   
    List price: $59.95
    SAVE $49.96
    Buy.com price: $9.99


    Dirt Devil 085805 Ultra Swivel Glide Bagless Upright Vacuum    
    FREE BUDGET SHIPPING 
    List price: $89.99
    SAVE $35.00
    Buy.com price: $54.99

    Promotions From Lenovo Canada

    Lenovo Canada  – PROMOTIONS

    This week’s product focus is on the 13 and 14 inch Notebooks which features the ThinkPad X301, T400, SL300 and SL400. There will also be a 48 Hour sale that begins Wednesday, Feb 18 and runs until Friday, Feb 19. There are ecoupons available for both promotions to offer greater discounts.

    Latest Promotions: 48 Hour Sale ( Feb 18-19)

    Sale on most Lenovo products! Save up to an additional 20% off select products when you use ecoupon: CAP48HOURSALE. 5% off ThinkPad SL, 10% off ThinkCentre A62, 16% off ThinkPad X61s, X301, X200, X200s, X200 Tablet, T400, T500, R400, R500, W500, W700,W700ds, 10% off Monitors, and 20% off Lenovo Branded accessories
    ecoupon: CAP48HOURSALE
    Week B promo 1
    Lenovo Canada 48 Hour Sale Feb18-19 use coupon CAP48HOURSALE for up to 20% extra savings off sale price

    Save on 13″ and 14″ Notebooks: (Feb 17-23)
    Promotional Copy: Save an additional 5-10% on 13″ and 14″ Notebooks and 15% on Warranty Upgrades. 10% off ThinkPad X301 and T400. 5% off ThinkPad SL300 and SL400
    ecoupon: CAP1314SAVINGS
    Save on 13 & 14 inch Lenovo Notebooks use coupon CAP1314SAVINGS from Feb 17-23

    Save an additional 10% off ThinkPad W500 ( Feb 17-23)

    Promotional Copy: Sale on the ThinkPad W500. Save an additional 10% on ThinkPad W500 when you use ecoupon: CAPWSERIESDOW. This gives you a combined savings of up to $800.
    ecoupon: CAPWSERIESDOW
    Save an additional 10% on ThinkPad W500 coupon: CAPWSERIESDOW from Feb 17-23

    Save up to an additional 15% off select ThinkPads ( Feb 17-23)

    Promotional Copy: Use ecoupon: CAPGREATSAVINGS to get up to an additional savings of 15%. 10% off ThinkPad X301,X200, T400, T500, R400, R500, W500, ThinkCentre A62 and 15% off X61s
    ecoupon: CAPGREATSAVINGS
    use coupon -CAPGREATSAVINGS to get up to an extra 20% off Lenovo ThinkPad, ThinkCentre and accessories Feb 17-23

    Options Promo: ( Feb 17-23)

    Promotion Type: % off Select Options
    Select AC Adapters: additional 12% off web price
    Select Lenovo Batteries: additional 10% off web price
    Lenovo Canada accessories and upgrades

    Ongoing Promotions:
    Save additional on ThinkPad notebooks (Ends March 31)
    Promo Copy: Save up to an additional 10% off ThinkPad notebooks over $1000 and 15% off ThinkPad notebooks over $1600. WARRANTY UPGRADE MUST BE INCLUDED IN CART (system and warranty must be 1 for 1 to receive discount). (excludes X200s, X200 Tablet, X301, W700)
    ecoupon: CATQ409CLOSEMORE
    Save up to 10% on top of sale price use ecoupon- CAPBEMYVALENTINE -valid till Feb 16

    Save additional on ThinkPad notebooks and ThinkCentre A Series desktops (Ends March 31)
    Promo Copy: 10% on cart totals of $1200+ and 15% off cart totals of $2000+ (discount is based on system price only). Available for current calls only. ThinkPad notebooks and ThinkCentre A Series desktops (excludes X200s, X200 Tablet, X301, W700, A61e)
    Save up to 10% on top of sale price use ecoupon- CAPBEMYVALENTINE -valid till Feb 16

    Save additional on ThinkPad notebooks and ThinkCentre A Series desktops (Ends March 31)

    Promo Copy: Use ecoupon to get a 5% additional off on ThinkPad notebooks and ThinkCentre desktops (excludes X200s, X200 Tablet, X301, W700, A61e)
    ecoupon: CATCLOSE4Q5
    Save up to 10% on top of sale price use ecoupon- CAPBEMYVALENTINE -valid till Feb 16

    Lenovo ThinkPad X61s Series Notebook

    Click here for great savings from Lenovo Canada!

    Save up to12% on select Lenovo accessories

    Free Shipping on award-winning ThinkPad notebooks

    Latest Electonic sale on buy.com

    Microsoft IntelliMouse Explorer Optical Mouse, Tilt Wheel Technology, 5
    Button(s), Wired, PS/2, USB (Platinum) 
     FREE BUDGET SHIPPING  

    List price: $49.99

    SAVE 84%    

    Buy.com price: $7.99

    Free Overnight Shipping from Katarina Jewelry  *Select expedited option during checkout

    Ships and Sold by Katarina Jewelry

     

    D-Link 7-Port USB 2.0 Hub    

    FREE BUDGET SHIPPING  

    List price: $39.99 

    Buy.com price: $25.99  

    $10.00 Mail-in Rebate 

    $15.99 After Rebate

    Nextar 1.5″ LCD Heart Shaped Photo Keychain, N1-506  FREE BUDGET SHIPPING   

    List price: $29.99

    SAVE 66%  

    Buy.com price: $9.99



    Westinghouse 26″ Widescreen 1080P LCD Monitor, 1920X1200, HDMI/HDCP,
    60Hz – Black
     
       FREE BUDGET SHIPPING  

    List price: $699.99

    SAVE 64% 

    Buy.com price: $249.99


    Dane-Elec 4GB microSDHC micro Secure
    Digital High Capacity Card
     
       FREE BUDGET SHIPPING     

    List price: $24.95

    SAVE $15.20      

    Buy.com price: $9.75

     

    Kingston
    2GB Single Module PC2-5300 667MHZ 240-Pin DDR2 Desktop Memory  
        
     

    FREE BUDGET SHIPPING       

    List price: $179.00   

    Buy.com price: $26.99      

    $7.00 Mail-in Rebate       

    $19.99 After Rebate

    Plantronics Explorer 340 Bluetooth Headset     FREE BUDGET SHIPPING    

    List price: $79.95

    SAVE 74%   

    Buy.com price: $19.99



    Philips 5.1 Surround Sound Multimedia Speakers, MMS460 
     FREE BUDGET SHIPPING    

    List price: $99.99

    SAVE 30%   

    Buy.com price: $69.99



    Pinnacle PCTV HD Pro Stick USB 2.0 TV Tuner (801e) – Factory
    Refurbished   
     FREE BUDGET SHIPPING    

    List price: $149.99

    SAVE 73%     

    Buy.com price: $39.99

    Microsoft Natural Ergonomic Desktop 7000     FREE BUDGET SHIPPING  

    List price: $119.95

    SAVE $62.20          

    Buy.com price: $57.75

    Logitech Labtec Wireless Laser Mouse for Notebooks – Refurbished 

    FREE BUDGET SHIPPING   

    List price: $39.99 

    SAVE 67%

    Buy.com price: $12.99

    Compaq Presario SR5507F Desktop PC, Athlon X2 (B) 4050e 2.1 GHz, 3 GB
    RAM, 250GB HDD, 16X DVD(+/-)R/RW 12X RAM (+/-)R DL LightScribe SATA
    drive, High Definition 6-Channel Audio, GeForce 6150SE nForce 430, Vista
    Premium, Keyboard and Mouse, Factory Refurbished 
    FREE BUDGET SHIPPING   List price: $699.99  

    SAVE 54%  

    Buy.com price: $319.99


    Microsoft Messenger Laptop Bag – 15.4″  
     FREE BUDGET SHIPPING    

    List price: $29.99

    Buy.com price: $21.99  

    $7.00 Mail-in Rebate   

    $14.99 After Rebate

    Gateway 17″ Widescreen LCD Monitor, 8ms, 1280 X 720, 16:9, DVI HDCP – 1
    Year Warranty
     FREE BUDGET SHIPPING   

    List price: $199.00

    SAVE $99.01 

    Buy.com price: $99.99

    Polaroid
    DPA08055S 8″ Dual-Screen Portable DVD & Game Controller, Refurbished

     FREE BUDGET SHIPPING   

    List price: $299.99

    SAVE 73%  

    Buy.com price: $79.99

    Pentax Optio Z10 8 Megapixel, 7x Optical Zoom, 2.5″ LCD Screen – SR 
    (Black)  
     FREE BUDGET SHIPPING  

    List price: $199.00

    SAVE 49% 

    Buy.com price: $99.99



    Cavalry Pelican 64GB SATA II and USB 2.0 2.5” Internal/External Solid
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     FREE BUDGET SHIPPING     

    List price: $299.99

    SAVE $150.00

    Buy.com price: $149.99



    Belkin Wireless G Router  
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    List price: $39.99

    Buy.com price: $34.99   

    $10.00 Mail-in Rebate   

    $24.99 After Rebate   



    Kingston 2GB Secure Digital SD Card
      

    Buy.com price: $7.45

    Unreal Tournament III (Xbox 360)  
     

    FREE BUDGET SHIPPING     

    SAVE $23.00   

    Buy.com price: $16.99

    FREE BUDGET SHIPPING         

    Canon PIXMA MX310 Office All-in-One Printer, Scanner, Copier and Fax
    with High-Speed Auto Document Feeder 
       FREE BUDGET SHIPPING   

    List price: $109.00

    SAVE $39.01

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    Palm
    Treo Pro Unlocked Smartphone w/GPS, WiFi, Windows Mobile 6.1 & 2MP
    Camera Plus Receive a Free Bluetooth Headset and an International Travel
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     FREE BUDGET SHIPPING    

    List price: $549.00

    SAVE $99.01

    Buy.com price: $449.99

    TomTom
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    Buy.com price: $129.99

    $30.00 Mail-in Rebate   

    $99.99 After Rebate 


    P3 International P4460 Kill A Watt EZ
    Electricity Usage Monito
    r  
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    List price: $59.95

    SAVE $29.96

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    Samsung HKT450 Bluetooth Speakerphone   
     FREE BUDGET SHIPPING     

    List price: $59.99

    SAVE $17.00        

    Buy.com price: $42.99

    NBA Champions 2007-2008 DVD    List price: $24.98

    SAVE $17.48   

    Buy.com price: $7.50

    Microsoft Office 2007 Home and Student     FREE BUDGET SHIPPING  

    List price: $149.95

    SAVE $65.96 

     

    Dell Latitude D600 Laptop Computer –
    Intel Pentium M 745 1.80GHz, 02.11b Wireless, 1GB DDR, 40GB HDD,
    CD-RW/DVD Combo, 14.1″ XGA,


    Windows XP Home – Refurbished 
        
     FREE BUDGET SHIPPING    

    Buy.com price: $349.99

    Puffed
    Diamond Heart Pendant in Sterling Silver 
       


    FREE BUDGET SHIPPING   List price: $199.00

    SAVE $159.01      

    Buy.com price: $39.99

    Ships from and sold by SuperJeweler

       

    Latest From Lenovo Canada


    Latest Promotions from Lenovo Computers: ThinkPad X61s, X200 and X301

    This week is Ultraportable week which features the ThinkPad X61s, X200 and X301.There will also be a 72 Hour sale that begins Wednesday, Feb 11 and runs until Friday, Feb 13.

    Latest Promotions: 72 Hour Sale: (Feb 11-13)

    • Promotional Copy: 72 Hour Sale! Use ecoupon:CAP72HOURSALE to save up to an additional 16% off ThinkPads X61s, X301, X200, X200s, X200 Tablet, T400, T500, R400, R500, W500, W700,W700ds, 5% off ThinkPad SL, 10% off ThinkCentre A62. 10% off Monitors, 20% off Lenovo Branded Accessories
    • ecoupon: CAP72HOURSALE
    • Save up to 20% on top of sale price during the Lenovo 72 Hour Sale- CAP72HOURSALE -From Feb 11-13

    Save up to 20% on top of sale price during the Lenovo 72 Hour Sale- CAP72HOURSALE -From Feb 11-13


    Ultraportable Week ( Feb 10-16)

    • Promotional Copy: Save an additional 10-15% on ultraportable notebooks plus get 12% off an extra battery until Feb 13 when you use ecoupon: CAPULTRAPORTABLE
    • ecoupon: CAPULTRAPORTABLE
    • Save an 15% off sale price on 15 inch Lenovo NotebooksSale from Feb 3-Feb 9

    Save an 15% off sale price on 15 inch Lenovo NotebooksSale from Feb 3-Feb 9

    Save an additional 10% on T400 and T500 ( Feb 10-16)

    • Promotional Copy: Save an additional 10% off ThinkPad T400 and T500 when you use ecoupon: CAPTSERIESDOW
    • ecoupon: CAPTSERIESDOW
    • Save an extra 10% on T400 and T500 Feb 10-16 use ecoupon CAPTSERIESDOW


    Save an extra 10% on T400 and T500 Feb 10-16 use ecoupon CAPTSERIESDOW

    Save up to 15% select products ( Feb 10-16)

    • Promotional Copy: Use ecoupon : CAPBEMYVALENTINE to save up to an additional Save up to an additional 15% off select ThinkPads
    • ecoupon: CAPBEMYVALENTINE
    • Save up to 10% on top of sale price use ecoupon- CAPBEMYVALENTINE -valid till Feb 16

     Save up to 10% on top of sale price use ecoupon- CAPBEMYVALENTINE -valid till Feb 16

    Ongoing Promotions:
    Save additional on ThinkPad notebooks (Ends March 31)

    • Promo Copy: Save up to an additional 10% off ThinkPad notebooks over $1000 and 15% off ThinkPad notebooks over $1600. WARRANTY UPGRADE MUST BE INCLUDED IN CART (system and warranty must be 1 for 1 to receive discount). (excludes X200s, X200 Tablet, X301, W700)
    • ecoupon: CATQ409CLOSEMORE
    • Save up to 10% on top of sale price use ecoupon- CAPBEMYVALENTINE -valid till Feb 16

     Save up to 10% on top of sale price use ecoupon- CAPBEMYVALENTINE -valid till Feb 16

    Save additional on ThinkPad notebooks and ThinkCentre A Series desktops (Ends March 31)

    • Promo Copy: 10% on cart totals of $1200+ and 15% off cart totals of $2000+ (discount is based on system price only). Available for current calls only. ThinkPad notebooks and ThinkCentre A Series desktops (excludes X200s, X200 Tablet, X301, W700, A61e)
    • ecoupon: CATQ409CLOSENOW  
    • Save up to 10% on top of sale price use ecoupon- CAPBEMYVALENTINE -valid till Feb 16

    Save up to 10% on top of sale price use ecoupon- CAPBEMYVALENTINE -valid till Feb 16

    Save additional on ThinkPad notebooks and ThinkCentre A Series desktops (Ends March 31)

    • Promo Copy: Use ecoupon to get a 5% additional off on ThinkPad notebooks and ThinkCentre desktops (excludes X200s, X200 Tablet, X301, W700, A61e)
    • ecoupon: CATCLOSE4Q5
    • Save up to 10% on top of sale price use ecoupon- CAPBEMYVALENTINE -valid till Feb 16

    Save up to 10% on top of sale price use ecoupon- CAPBEMYVALENTINE -valid till Feb 16

    Options Promo: ( Feb 10-16)

    • Promotion Type: % off Select Options
    • Select Lenovo Docks and Port Replicators: additional 12% off web price
    • Select Lenovo Keyboards and Mice: additional 10% off web price
    • Save up to12% on select Lenovo accessories

    Save up to12% on select Lenovo accessories

    More Promos:

    Lenovo ThinkPad X61s Series Notebook

    Click here for great savings from Lenovo Canada!

    Save up to12% on select Lenovo accessories

    Free Shipping on award-winning ThinkPad notebooks

    Lenovo (Canada) Inc.

    check out these Amazing Last Minute Deals and Sneak Previews

    The BIG GAME is on Sunday, February 1, 2009 and Buy.com has a great selection of High-Definition TVs from Pioneer to Sharp – 1080p, LCD and more! See links below.

    Finally, check out these Amazing Last Minute Deals and Sneak Previews:

    * Philips PowerSquid Power Strip for $8.99 (save 82%)
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    Maximising AC/DC efficiency from full-load to no-load

    While maximising power efficiency at full-load is a top priority in the design of an AC/DC supply, standby power considerations and new power-efficiency standards loom larger. Thus, apart from the general subject of “high efficiency,” designers are looking harder at ways to maximize energy-savings from end to end. Indeed, saving milliwatts is of particular concern with designs that use AC power adapters, which are proliferating worldwide.

    Quasi-resonant control, valley-voltage switching, and multi-mode operation (i.e., pulse-skipping) offer one solution. In this article, we’ll summarize the techniques being used in some of today’s green-type IC controllers to minimize energy losses across the converter’s entire load range.

    Limiting standby power
    In a design philosophy that embraces smart electronics and “instant on” response, today’s AC/DC power converter often spends a good amount of its time in the standby mode, where there’s always some sort of power drain. It’s basically the same problem whether we’re talking about a remote-controlled TV or video equipment, an external low-voltage power supply for cordless telephones or wireless routers, office equipment (copiers and printers), or devices such as battery chargers for laptop computers. The actual power drawn in the standby mode of individual converters is small, typically 0.3 to 20 watts. But however small the standby power, the sum total becomes large when you multiply it by the number of consumer, commercial, and industrial systems in use.

    Indeed, standby power accounts for perhaps 10 per cent of the electricity used in homes and offices in the European Union, and about four per cent of the total electricity used in the United States. Developing standards such as Energy Star focus on energy-savings at no-load and light-load conditions, higher efficiency in normal operation, less total harmonic distortion (THD), and close to unity power factor (PF). The Table summarizes the Energy Star standards for external single-voltage AC/DC and AC/AC power supplies.

    Meeting the standards
    How do system designers meet Energy Star and other developing international standards? They apply active clamp and reset techniques, transition-mode and interleaved multi-phase PFCs, pulse-skipping, quasi-resonant control and valley-voltage switching. Flyback converters with quasi-resonant control, valley-voltage switching and pulse-skipping offer one of the best solutions.

    Flyback converters, widely used in consumer applications, are low cost, easy to control, and support multiple output rails (see Fig. 1, in this case using the UCC28600 quasi-resonant chip). Quasi-resonant control facilitates the use of soft-switching, which improves efficiency and energy-savings. In quasi-resonant operation, the primary main switch has a much lower turn-on voltage. The energy that charges the switch capacitance when it’s in the off-state is regenerated to the source.

    In contrast, continuous and discontinuous current mode (CCM and DCM) operations in hard-switching topologies suffer high turn-on losses. To achieve better energy-savings across the entire load range, the flyback converter can be operated in the frequency foldback mode (FFM) and the pulses kipping mode, depending on load conditions. FFM circuitry cuts back on the switching frequency as the load becomes less, thus lowering switching losses. When the load becomes very light, the hysteretic mode (also known as green-mode or burst operation) comes into play to initiate pulse-skipping. The pulse-skipping reduces switching losses and achieves better energy-savings for lightload and no-load conditions.

    For applications with frontend PFC pre-regulators, additional energy-savings can be obtained by turning off the PFC operation at very light load.

    The circuits
    Quasi-resonant control describes a flyback converter operated in critical conduction mode (CrCM) with zero voltage switching (ZVS), or so-called valley-voltage switching (VVS). The ZVS/VVS operation results from a LC resonance formed by the primary winding inductance of the flyback transformer and the total equivalent capacitance across the primary main MOSFET switch (CDS). The voltage across the MOSFET drops during the resonant switching process. The flyback controller detects the drop and turns on the primary switch at valley points. Valley-voltage switching must meet two conditions. The first is:

    Vin≤ N (Vout + VD )

    where N is the transformer turns ratio. In this situation, the reflected secondary voltage is high enough to force the primary VDS voltage to zero. As a result, the primary side MOSFET can be turned on with zero voltage across it. Secondly,

    Vin > N(Vout + VD )

    Under this condition, the reflected secondary voltage is not able to steer the VDS voltage to zero. Instead, we have a “voltage valley.” Figure 2 shows typical VVS operation from quasi-resonant flyback converters. The valley voltage would be extended to zero-valley if the first equation is met. Then we achieve zerovoltage switching.

    ZVS/VVS brings high energysavings and an improvement in efficiency. For a given capacitance, the switching power, Psw, is determined by the voltage across the capacitor, CDS as well as the switching frequency, fs:

    Psw = 0.5 CDS VDS2 fs

    A flyback converter with hard-switching turns on the switch at a high voltage, which results in high switching-power. The energy stored in the capacitor CDS is dissipated through the MOSFET channel resistance during the next switching cycle, thus manifesting as a switching-power loss. Such a power loss is especially significant in off line AC/DC applications where a high DC-link voltage results from the rectified 85-285 VAC line voltage.

    Conversely, the same flyback converter, if operated in the quasi-resonant mode with valley-voltage switching, will turn on the switch at a lower voltage. The voltage is reduced through LC resonance as the energy stored in the capacitor is discharged and recycled back to the DC link capacitor, CBLK, instead of being dissipated through the MOSFET channel resistance.

    In general flyback operation, quasi-resonant control from a small load percentage to full rated load implies multi-mode operation for best efficiency. That is, we subdivide converter operation into two modes: normal quasi-resonant mode with variable on-time control; and constant on-time control, the aforementioned frequency foldback mode (FFM). For example, a quasi-resonant controller may be designed for operation from 15 per cent to 50 per cent load during which time it’s in the FFM mode. The frequency decreases as the load becomes less and so switching power losses are reduced further. From 50 per cent to full-rated load, the controller cuts down on its frequency as loading increases. Usually the switching frequency is clamped to below 150kHz to minimize EMI and meet EMI requirements.

    Pulse-skipping
    Pulse-skipping, also defined as green-mode or burst operation, offers the best energy-savings at ultra-light loads. At such load levels, it’s easier to maintain output voltage regulation. So there’s switching only when the output voltage is moving out of regulation. Extra switching actions just contribute to energy-waste. For example, energy is wasted in the dissipative snubber circuit every switching cycle. Such energy losses are eliminated when we apply pulse-skipping.

    Pulse-skipping initiates switching only if the output voltage drops below a certain threshold value. During this time, the controller (on the primary side) applies a pulse packet to the transformer to bring up the output voltage to the upper limit of the hysteretic window to keep the output in regulation. Then the switching circuitry is disabled. This correction circuitry comes back into play when the output voltage again approaches the lower limit of the hysteretic window.

    Turning off PFC at light-load saves energy
    Power-factor-correction (PFC) brings no real benefit at light load. Essentially, all the circuitry does is consume power. A properly configured flyback quasiresonant controller may contain a dedicated pin to conveniently implement such function and automatically turn off PFC circuitry at a predetermined load condition. By adding minor external circuitry (a diode and a resistor, for example Ds and Rs as shown in Fig. 1), the designer can use the status pin as an indicator to reduce the primary peak-current. This design technique helps to reduce harmonic power at light loads, and thus power losses are less. In addition, we can reduce audible noise.

    In summary, the flyback converter, using quasi-resonant control and pulse-skipping techniques, will maintain high efficiency over the entire load range. Figures 3 and 4 present typical test results from a 65-watt flyback converter.

    Figure 3 shows typical efficiency from a quasi-resonant flyback converter; Fig. 4 shows how pulse-skipping can minimise losses at standby power levels.

    Measuring battery current with precision

    How long will it run?
    When power fails, many home and commercial alarm systems go to a backup battery, most commonly a 12-volt sealed leadacid type. If you’re able to accurately sense the current draw, and the battery is well-characterised, you’ll be able to accurately determine the amount of time remaining before your mission-critical system dies.

    With careful design, you can measure battery current to within 0.2 per cent of full scale. With that information, the most accurate gauging systems, taking battery age, temperature, selfdischarge, and discharge-charge cycle history into account, can usually estimate remaining battery life to within 1 per cent. The sealed lead-acid (SLA) batteries used in most backup systems specify between 250 and 1,000 full discharge-charge cycles over their service life, which can be as long as three to five years with good treatment. Home-alarm systems may draw as much as a few amperes, though 1 amp or less is common in today’s typical system. An uninterruptible power supply (UPS) for a single computer may draw 16 amps or more from the battery at full load. A network equipment rack filled with a large organization’s switches and routers, plus built-in wireless and broadband modems may draw 50 amps or more. The system designer’s end goal is to be able to accurately determine remaining battery life across a wide range of load demands.

    Apart from its basic function, current-sensing circuitry is often part of a system for recharging the battery as fast as possible. Integrated solutions to this problem exist using such chips as Analog Devices’ ADP3808 battery charger IC, which features both fast charge mode and float charge mode. Still, for flexibility and to maintain high accuracy up to 0.2 per cent over temperature, a discrete solution is often preferable. Either way, the best estimate of remaining charge is obtained by active methods such as current sensing, or the more accurately you can do that, the more accurate the end result.

    Source characteristics
    SLA batteries are very robust compared to most chemistries. Their charge capacities decrease at temperatures below 25°C and at higher discharge rates, so demanding applications will shorten battery life. Charging a SLA battery at more than a 0.2 C rate, one fifth its charge capacity in ampere-hours, can damage the battery and decrease its ability to store charge. Proper charging, including varying the charging voltage with temperature and correctly terminating at fullcharge, maximises the expected battery life.

    The SLA batteries self-discharge 3 to 10 per cent of their capacity each month if they sit at room temperature without being charged. In backup applications, continuous floatcharging at the total cell-voltage eliminates the self-discharge problem and avoids damage from overcharge.

    Basic considerations
    Sensing begins with converting the battery current to a voltage as measured across a low-value sense resistor. The sense resistor connects between the battery and the load, in either the negative or positive leads. Set up the circuit for positive-lead sensing when possible; that way, the system ground won’t be disrupted.

    Next, find an appropriate low-offset op amp to boost the ultra low-voltage input before introducing it to an A/D converter for sampling. Finding a low-offset amplifier with the required high input-voltage range can be difficult for high-voltage applications. In these cases, an instrumentation amplifier such as the AD8210 (high-voltage, bidirectional current shunt monitor), will often stand in well. For an accurate measurement, the amplifier’s input range needs to extend beyond the supply rails.

    For a 12-volt system, on the other hand, it’s much easier to find low-offset amplifiers for sensing the current at the negative terminal using low-side current sensing. The input range still needs to extend below ground to include the amplifier’s supply current in the measurement.

    For power backup systems, current sensing is a low-frequency activity, so 30 Hz to 50 Hz sample rates are more than enough as the load currents do not vary quickly and the resultant Nyquist rate is about 100 Hz. Rates of 10 Hz or lower minimise the overhead on the processor monitoring the current, while still providing accurate estimates of remaining charge. The low sample rate emphasises the need for amplifiers with low 1/f noise for best accuracy. In addition, the offset voltage drift (TCVOS) of an amplifier due to temperature variation mimics the low-frequency noise, so it should be minimal as well. The typical discharge temperature range for many SLA batteries is -20 to +50°C.

    The maximum system current sets the sense resistor value and absolute measurement accuracy. For example, a maximum sense-resistor voltage of 50 mV complies with the input limits of an amplifier while still providing some operating margin over temperature.

    Given the above requirements, an auto-zero amplifier such as Analog Devices’ AD8638 is a good candidate. The AD8638 can handle inputs up to 100 mV below ground and it can be directly powered from a 16-volt supply. Its auto-zero design gives the required low offset for accurate low-current measurement—10 microvolts at +25°C, and 20 microvolts maximum over -40 to +125°. Furthermore, its auto-zero architecture is lownoise between 0.1 Hz and 10 Hz. If you can get around the need for error correction at the A/D converter’s output, you can use less-expensive, lowerresolution A/D converters. The measuring front end’s offset and noise should both be minimised for the best accuracy without adjustment.

    Sensing only discharge current cuts cost
    The A/D converter’s input range sets the front-end gain for the maximum sense voltage. A/D converters with 5-volt ranges are readily available. Sensing both drain and charging current requires negative and positive supplies and a converter with a bipolar input range. A negative supply can be built with a well filtered buck-boost regulator, but the additional circuitry adds complexity and cost.

    After a loss of mains power and a subsequent restoring of service, the power will normally be up long enough to charge the backup battery. For that reason, measuring charging current is usually unnecessary for a wellcharacterised SLA battery and well-behaved charging circuit. A unipolar input range and supply are sufficient for sensing current drain in cost-sensitive applications. Measuring the discharge and tracking the number of discharge-charge cycles is usually all you need to accurately estimate the battery condition.

    The circuit
    Figure 1 shows the current-sensing circuit. The 0.01-ohm sense resistor develops a full-scale 50 mv voltage from a 5-amp system. Resistors R2A/R1A and R2B/R1B configured for amplifier A1 establish a gain of 100, and thus the amp will produce a 5-volt output from the 50-mV input. R1A and R1B also provide input current limiting to avoid damaging the amplifier’s on-chip ESD diodes. C1A and C1B limit the 3 dB circuit bandwidth to 10.7 Hz.

    The large capacitive load from the A/D converter’s input may cause instability, so R3 is included to decouple it. Without R3, the amplifier’s output impedance and the load capacitance may form a poorly damped resonance, which can cause ringing or oscillation at high frequencies. The required value for R3 will vary with the A/D’s input capacitance and should be checked in the actual circuit. Most A/D converters have very low input currents, so the DC error introduced by R3 will be negligible. R3 may be eliminated if the A/D’s input capacitance plus the board layout capacitance is less than about 60 pF.

    To avoid latchup and possible damage, connect the ground lead first, followed by VDD, and then the inputs to the device. Input voltages should never exceed VDD or go more than 100 mV below ground.

    At the start of any backup event, the current-sensing circuit will either be powering up from standby or recovering from overload. Either condition requires time for the circuit to settle before it can measure current and it will require additional settling time due to the 10.7 Hz filter. It’s a good idea to wait at least 300 ms before taking the first current measurement.

    Front-end errors
    The errors associated with amplifier A1 and its sensing circuit include voltage offset, resistor mismatch, and noise. For an autozero amplifier such as the AD8638, the maximum offset over a -40°C to +125°C range is 20 microvolts, as previously indicated. If you use 0.1 per cent resistors for R1A/R2A and R1B/R2B, the worst-case gain error will be 0.2 per cent.

    Noise comes from several 1.2 microvolts from 0.1 Hz to 10.7 Hz. It also contributes a negligible amount of noise from noise current through R2B, R1B and R2A. Resistor Rsense is small enough that its noise contribution can be neglected. Resistors R1A, R2A, R1B and R2B contribute a certain amount of thermal noise, given by the familiar equation:

    Vn(R) = (4kT BWnR)1/2

    where BWn is noise bandwidth (1.57 times the 3 dB signal bandwidth for a single-pole circuit). Resistor R2A’s outputreferred noise from the equation above must be divided by noise gain, Avn, to determine its input-referred noise, but all other noise terms are already input-referred. The circuit’s total input noise is the RMS average of all the terms:

    Vnt=[Vn(R1A)2 + Vn(R1B)2 +
    Vn(R2B)2 + (Vn(R2A)/Avn)2 + (Vn
    amp)2]1/2

    In this case, Vnt is 1.21 microvolts, close to the noise from the amplifier itself. The total worst-case front-end error voltage is the sum of Vos and Vnt, a total of 22 microvolts. It’s likely to be less than this because of the system’s limited operating temperature range, but 22 microvolts is the upper bound. So the lower limit on the current we can distinguish is 22 microvolts divided by Rsense, or 2.2mA. The current sensed and amplified output from this error voltage is 2.2 mV, which represents 0.04 per cent full-scale error. The 0.2 per cent gain error from resistor mismatch represents the dominant error source from the front end, but it can be calibrated out if monitoring system overhead allows it.

    A/D converter choice A 12-bit A/D converter with 5- volt full-scale range has 1.22 mV LSB size. A 10-bit A/D converter with 5-volt full-scale range has an LSB four times that, or 4.88 mV. A 10-bit A/D’s step size error (DNL) will be 0.1 per cent of full scale, while a 12-bit A/D’s step size error is just 0.024 per cent. The 12-bit A/D gives better accuracy at currents well below full-scale, but will be more costly.

    Integral non-linearity (INL) contributes additional errors. The designer can chose a higherresolution A/D if more precision is needed, but the lowest few codes will come from offset and noise. For a low-cost system, 10-bit resolution is usually enough.

    The converter’s accuracy also depends on the accuracy of the reference. Some converters, such as Analog Devices’ AD7910, take its reference internally from VDD, so they require a well-regulated 5-volt supply for accuracy. A precision reference can be used to power low-power converters. The noise from the reference should also be counted in the error analysis. C3 and C4 decouple low- and high-frequency noise from lines to the battery. C5 and C6 smooth VDD during conversion.

    PC board layout
    Getting the best accuracy at low battery currents requires some care in PC board layout. A 2mA increase in battery current creates a 20 mV increase in sense voltage. This produces an additional 20 nA in R1A. A 10 ¼V offset may produce a 10 nA error current in R1B. With these incremental circuit currents, leakage currents from external circuitry and the PC board can significantly degrade accuracy. Worse, leakage may vary unpredictably with temperature and humidity. Cleaning the PC board and all insulating surfaces to remove flux and other residues after assembly will help. Board leakage can be minimised by encircling the input connections with a guard ring maintained at ground potential for a low-side sense circuit. Apply guard rings to all planes of the board. Wider rings give better leakage reduction.

    For precision measurements, use a 4-wire Kelvin connection to Rsense. Place this resistor close to R1A-B and the amplifier.

    A connection between dissimilar metals at a solder joint forms a thermoelectric junction, with an electric potential that varies with temperature. This is the Seebeck effect exploited in thermocouples, but it is undesirable in a precision voltage measurement system. The temperature coefficient for the emf at a package pin-PC board connection may be as high as 35 mV/°C. Symmetrically match and minimise the number of soldered connections between resistors and the amplifier’s inverting and non-inverting inputs to avoid the inaccuracy of thermocouple effects. Make the input connections of the R2AC1A and R2B-C2B component groups look as much alike as possible, and minimise soldered connections here, too.

    Another source of inaccuracy is thermal drift from warm-up. Leaving the amplifier powered up will minimise this error source. For auto-zero amplifiers, the error is low enough to be negligible.

    Select a low-quiescent supply current amplifier tol minimise thermal effects on accuracy. With the near-DC input, the amplifier draws an unchanging current close to the quiescent specification when it drives a CMOS A/D converter’s high input impedance. For example, in an SOT23 package, the amplifier has a thermal resistance around 230°C/W. With a 12-volt supply, the junction temperature is less than 3 degrees above ambient. This decreases the effects of operating conditions on Vos.

    Overall accuracy and testing
    Current sensing and battery capacity are related when it comes to accurately determining remaining charge. Charge is current multiplied by time, so current measured at regular intervals gives this information. If 1amp is measured at t0, and 900mA is measured 100 ms later, the average charge taken from the battery is 0.095 coulombs over the 100 ms interval. If this average current flow continues for an hour, the discharge rate is 0.95 A- h. The smallest measurable charge quanta are set by the time between measurements and current sensing accuracy. The total average current sensing accuracy is the RMS average of all the input referred amplifier front end and A/D converter errors. Combining all the worst-case input-referred errors gives a total of 2.356mA for each measurement. This error gives accuracy to 2.356 (10-4) coulombs for every measurement, assuming negligible inaccuracy in 100 ms measurement time intervals. For 1 amp, or 0.1 coulomb full-scale per measurement, that is 0.236 per cent of full scale. A fresh 7 A-h backup battery contains 7(3600) = 25,200 coulombs when fully charged. The error for any individual charge measurement is very small compared to this total capacity.

    A precision voltage source should be used to test the circuit. Apply the test voltage directly across the sense resistor with battery and load disconnected, and check for correct codes at the A/D output. Remember the voltage source’s low-frequency noise and voltage-setting error in any measurement. Actual loads should also be checked with the battery used in the application.

    References
    1. AD8638/AD8639 16V Auto-Zero, Rail-to-Rail Output Precision Amplifiers, datasheet, Analog Devices, 2007.

    2. AD7910/AD7920 10-/12-Bit ADCs in 6-Lead SC70, datasheet, Analog Devices, 2005.

    3. ADR360…ADR366 Low Power, Low Noise Voltage References with Sink/Source Capability, datasheet, Analog Devices, 2007.

    4. Enersys NP7-12, 12V 7Ah Sealed Lead-Acid Battery, datasheet.

    5. Jung, Walt, Editor, Op Amp Applications Handbook, Elsevier, Burlington, Massachusetts, 2006.

    6. Kester, Walt, and Buxton, Joe, Power and Thermal Management Section 5 – Battery Chargers, Analog Devices, 1998.

    7. Keithley Series 2400 SourceMeter Line datasheet, 2007.

    8. Nolan, Eric and Moghimi, Reza, Demystifying Auto-Zero Amplifiers, part 2, Analog Dialogue 34-3, 2000.

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