DDR SDRAM The Memory of Choice for Mobile Computing

1
DDR SDRAMThe Memory of Choicefor Mobile
Computing

• Bill Gervasi
• Technology Analyst, Transmeta Corporation
• Chairman, JEDEC Memory Parametrics
• bilge_at_transmeta.com

2
Topics to Cover

• Market Segments Fragments
• Mobile Design Architectures
• DDR and SDR Power Analysis
• DDR SO-DIMM Details

3
Segments Fragments
Servers Workstations PC Segment 2 PC Segment 1 PC
Segment 0 Mobile Graphics
DDR
PC100
PC133
PC100
DDR
PC133
Rambus
PC100
DDR
PC100
PC133
DDR
PC100
DDR
PC133
PC66
PC100
DDR
PC133
DDR (x16 and x32)
SS167
2H99
1H00
2H00
1H01
2H01
4
RAM Evolution
3200MB/s
MainstreamMemories
DDR II
2100MB/s
DDR
1000MB/s
SDR
400MB/s
Simple,incrementalsteps
320MB/s
EDO
FP
5
Mobile Designs
Mobile Memory Controller

• Two Sockets, T-stub
• 133MHz clock (for now)
• 2.1GB/s transfer (for now)

6
Butterfly SO-DIMMs
Motherboard
SO-DIMM
SOCKET
CPU
CPUNB
SO-DIMM
SOCKET

• Perfect for notebook
• Especially thin light!
• Single access door to both SO-DIMMs
• Internet Appliance 1 or 2 SO-DIMMs

7
Mobile Market Requirements

• Low power, low heat

• Long battery life
• Small form factor
• End-user upgrade

8
Power CV2f

• Keys to mobile
• design
• Reduce C and V
• Match f to demand
• Minimize duty cycle
• Utilize power states

• Factors
• Capacitance (C)
• Voltage (V)
• Frequency (f)
• Duty cycle ()
• Power states

9
Power Capacitance
Capacitance Voltage Frequency Duty cycle Power
states

• DDR capacitance 20 less than SDR
• Tight circuit board design
• Low parasitic sockets

10
Power DDR vs SDR
Capacitance Voltage Frequency Duty cycle Power
states
Lower Voltage meansLower Power
PC133 (3.3V) 2.0X
PC100 (3.3V) 1.2X
PC266 (2.5V) 1.0X
11
Power DDR vs SDR
Capacitance Voltage Frequency Duty cycle Power
states
Double the Bandwidth yet Lower Power
PC266 1.0X
PC100 .31X
PC133 .25X
12
Power Frequency
Capacitance Voltage Frequency Duty cycle Power
states

• Memory speed to match task demand
• Adjust memory clock for lowest power
• Stream back to back operations on open bank, then
  close
• DDR burst efficiency really shines

13
Power Duty Cycle
Capacitance Voltage Frequency Duty cycle Power
states

• Caches minimize memory demands
• DDR cuts burst time in half
• Get back into low power state sooner

14
Long Battery Life

• Lowest power to perform a task
• Desktop performance expected
• Battery extending technologies
• SpeedStepTM
• LongRunTM

SpeedStep and LongRun are trademarks of Intel
Corporationand Transmeta Corporation,
respectively
15
Introducing LongRunTM
Capacitance Voltage Frequency Duty cycle Power
states
LongRun
SpeedStep
The number 11 is a trademark of Spinal Tap
16
LongRunTM Technology
Capacitance Voltage Frequency Duty cycle Power
states

• Smart reprogramming of memory frequency based on
  demand
• CPU monitors trends in CPU demand
• Automatically adjust CPU voltage,CPU memory
  frequency as needed
• Utilize all memory power states
• Lowest power state possible
• Close banks between bursts

LongRun is a trademark of Transmeta Corporation
17
LongRunTM Advantage
Capacitance Voltage Frequency Duty cycle Power
states
18
Mobile Market Requirements

• Long battery life
• Low power, low heat
• Small form factor

• End-user upgrade

19
End User Upgrade

• DDR SO-DIMM Status
• 63.6 x 31.75mm
• 200 pins on .60mm centers, staggered
• x64 and x72 (ECC) supported
• JEDEC specification votes being counted
• Multiple mobile designs in progress
• Samples in test now, production 1Q01
• Also great for small (Flex ATX) desktop

20
Conclusions
DDR

• Memory of choice for the future
• Enables mobile computing
• Low power yields long battery life
• Small form factor end-user upgrades
• Smart power management schemes

21
Summary

• DDR is here today
• Double the bandwidth at lower power
• Evolutionary design change over SDR
• Applies to all market segments
• Industry Standards
• Detailed complete data sheet models
• Module designs on the web
• Visit http//www.ami2.org

22
Thank You