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DDR Penetrates Mobile Computing

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  1. DDR PenetratesMobile Computing Bill Gervasi Technology Analyst Chairman, JEDEC Memory Parametrics Committee

  2. Agenda • Why DDR for Mobile? • Standard versus cached DRAMs • DDR Configurations • Introducing the DDR MicroDIMM • Mobile System Design Guidelines

  3. Reasons for DDR in Mobile • Performance • Power • Form factors

  4. SDR SDRAM Evolution 4800MB/s DDR II MainstreamMemories 2700MB/s DDR333 2100MB/s DDR266 Simple,incrementalsteps 1000MB/s

  5. Power: DDR vs SDR DDR-266 3.2X DDR-333 2.6X est. PC-100 1X PC-133 0.8X

  6. RelativePower CPU ClockLatency** Active on PowerState* 100% 4% 12% 0 x 5 = 0 Inactive on 3 x 5 = 15 Active off 1 x 5 = 5 Inactive off 0.2% 4 x 5 = 20 * Not industry standard terms – simplified for brevity ** Assuming memory clock frequency = 1/5 CPU frequency ClosedPage Sleep OpenPage  0.4% 200 x 5=1000 DDR Power Management

  7. Implications: Mobile Power • Encourages closed page policy • Precharge banks as soon as data read • Takes latency hit to reactivate

  8. Closed Page Power Profile Higher Power Power Profile NOP ACT R R PRE NOP Command Activity Power Profile NOP ACT W W PRE NOP Command Activity Lower Power

  9. Cached DRAM Power Profile Higher Power Power Profile NOP ACT R-PRE R R NOP Command Activity Depending on cached DRAM architecture Power Profile NOP ACT W W PRE NOP Command Activity Lower Power

  10. Standard vs Cached • Cached DRAM architectures save power • Improved closed page performance • Latency reduction on page hits • Lower power profile (See my other presentation at Platform 2001… “An Analysis of Virtual Channel and Enhanced Memories Technologies”)

  11. DDR Configurations TSOP-II DIMM NEW! FBGA TQFP SO-DIMM NEW! MicroDIMM

  12. Next: Small Packages FBGA(fine pitch BGA) • Lower inductance • Lower capacitance • Smaller footprint • Tighter layouts enabled Details: Package size = 104 mm2 = 54% smaller Inductance: 1.7nH lower Inductance variation, pin to pin: 3X less Capacitance: 0.5pF lower Performance gain: 300ps of data valid time

  13. DDR Chip Configurations • TQFP devices for point to point • x32 … 64Mb, 128Mb coming • 100 pins, 16 x 22 mm footprint • TSOP devices • x4, x8, x16 … 64Mb, 128Mb, 256Mb • 66 pins, 12 x 22 mm footprint • FBGA selection in process • x4, x8, x16 … 128Mb, 256Mb, 512Mb/1Gb coming • 60 ball, 6.4 x 11 mm minimum footprint

  14. DDR Module Configurations • DDR SO-DIMM – done! • Sockets, modules in production • DDR MicroDIMM – in process • Task group active • System application combinations • One module only • Soldered down + module • Two modules

  15. Next: DDR MicroDIMM • Half the size of the DDR SO-DIMM • Half the capacity if using TSOP – or – • Same capacity if using FBGA • Target markets: • PDAs • Internet appliances • Subnotebook computers

  16. SO- and Micro- DIMMs DDR SO-DIMM TSOP:67.6 x 31.75 mm = 2146 mm2 4 or 8 devices 200 pins on 0.6 mm pin pitch(supports ECC) --------------------- FBGA:Under consideration if needed DDR MicroDIMM TSOP:45.5 x 30 mm = 1365 mm2 4 devices 172 pins on 0.5 mm pin pitch(no ECC) --------------------- FBGA:45.5 x 25 mm = 1137 mm2 4 or 8 devices

  17. Module Status • DDR SO-DIMM • DDR266 validated • DDR333 under analysis • Looking okay to 333 MHz with TSOP • DDR MicroDIMM • TSOP easy, DDR266/333 speeds • FBGA package needed to fit 8 chips • Possible schedule • Sample April 2001 • Approved spec June 2001

  18. Module Densities

  19. Small System Configurations • One data bus, one address bus • Point to point, single socket • Series damped data, address, clock • Two sockets • SSTL_2 terminated data • Series damped address, clock • Top/bottom or butterfly arrangement

  20. Top/Bottom Mobile Modules Motherboard • Standard for many current full size notebooks • Hard to get at one of the modules • Thickest form factor Module SOCKET CPU CPU Socket Module Note: There may be patents regarding use of these layouts

  21. Butterfly Mobile Modules Module SOCKET CPU Motherboard • Perfect for thin/light notebooks & subnotes • Single access door to both modules • Also good for small form factor desktop PCs -- or -- CPU Module Socket Note: There may be patents regarding use of these layouts

  22. MicroDIMM Designs You know the DDR SO-DIMM, so… …let’s focus on the MicroDIMM design First, system configurations…

  23. RAM Conn RAM 25 25 RAM RAM Clock Topology CK CK

  24. RAM RAM 25 22 Data Topology, 1 Slot DQ, DQS, DM 2 bank Conn

  25. RAM RAM Conn RAM RAM 25 22 22 25 Data Topology, 2 Slot DQ, DQS, DM 2 bank VTT Conn 2 bank

  26. RAM RAM RAM RAM RAM RAM RAM RAM 10 A/C Topology, 1 Slot Two Bank MicroDIMM shown Conn A, BA, WE, RAS, CAS

  27. RAM RAM RAM RAM Conn 10 A/C Topology, 1 Slot One Bank MicroDIMM shown A, BA, WE, RAS, CAS 11pF

  28. RAM RAM RAM RAM RAM RAM RAM RAM RAM RAM RAM RAM Conn 10 A/C Topology, 2 Slot Two Bank MicroDIMM shown One Bank MicroDIMM shown Conn A, BA, WE, RAS, CAS 11pF

  29. RAM RAM RAM RAM Conn 10 CS & CKE Topology One or Two Bank MicroDIMM shown CS, CKE 11pF

  30. Increasing Focus on Systems • JEDEC packaging committee charter extended to include module sockets • Land pattern for pin pads • Mechanical support tab locations • Orientation holes • Shadow area of socket body • Module height & centerline • Working system configuration first time!

  31. DDR MicroDIMM Clearances 3.78mm max 4.43mm max discretes Standard socket, double sided memory module Standard socket, single sided memory module 3.78mm max 5.40mm max 0.65mm min Reverse socket, double sided memory module Reverse socket, single sided memory module

  32. Socket Spec Status • Merging 144, 172 pin sockets into single parameterized MO-214 spec • Priming spring included • Shoves module “to the left” • Redimensioned by left edge, not center • Edge bevel defined

  33. Conclusions • DDR solutions for mobile growing • Cached DRAM would be even better • Point to point and DDR SO-DIMM done • DDR333 development in progress • FBGA packaged DDR coming • DDR MicroDIMM development on track

  34. DDR Memory of choice for the future

  35. Thank You