Memory Modules OverviewSpring, 2004

Bill GervasiSenior Technologist, Netlist

Chairman, JEDEC Small Modules& DRAM Packaging Committees

Many Applications,

Many Configurations

Module Configurations

• DDR1– Unbuffered DIMM– Registered DIMM– SO-DIMM– Micro-DIMM

• New:– 32b-DIMM

• In development:– 4 Rank RDIMM

• DDR2– Unbuffered DIMM– Registered DIMM– SO-DIMM– Micro-DIMM

• In development:– Mini-RDIMM– 4 Rank RDIMM– 4 Rank SO-DIMM– 4 Rank Micro-DIMM– Fully Buffered DIMM– DDR3 modules

All JEDEC modules include Serial Presence Detect (SPD) EEPROM for boot time detection of capabilities

DDR2 Speed GradingCommittee approved standard speed grades:

400 MT/s 200 MHz DDR2-400 PC2-3200

533 MT/s 266 MHz DDR2-533 PC2-4200

667 MT/s 333 MHz DDR2-667 PC2-5300

800 MT/s 400 MHz DDR2-800 PC2-6400

Data Rate

X64/x72 bit data bus * chip speed

Clock Speed Chip Bin Module Bin

DDR2 Unbuffered DIMM

• Same physical size as DDR1: 133 mm (5.25”)• New socket

– More pins… 184 240 pins– Tighter pin pitch… 1.27 1.0 mm

• “Same plane referencing” pinout• Target markets unchanged

– Workstations– Desktop PC

• Status: APPROVED– 1 Rank x8, 2 Ranks x8, 1 Rank x16

DDR2 Registered DIMM

• Target markets unchanged– Servers– High-end Workstations

• New feature: Address Parity– Checks integrity of every

address and commandsent

• Status: APPROVED– 1 Rank x8, 2 Rank x8, 1 Rank x4, 2 Rank x4– With or without address parity

DDR2 SO-DIMM

• Same width, shorter than DDR1: 67.6 x 30 mm• Same 200 pin socket as DDR1

– Uses 1.8V key position• No longer supports x72 (ECC) or registered• Target markets change from DDR1 to DDR2:

– DDR1: Mobile, blade server– DDR2: Does not support blade server

• Status: APPROVED– 2 Rank x16, 1 Rank x8, 1 Rank x16, 2 Rank x8

DDR2 Micro-DIMM

• Larger module, same footprint as DDR1: 52 x 30 mm• New connector

– High pin count mezzanine connector– Two part: half on motherboard, half on module– 0.4 mm pitch

• Status: APPROVED– 1 Rank x16, 2 Rank x16

DDR1 32b-DIMM

• New to DDR1… noDDR2 version yet

• X32 only, 90.18 mm wide• Ultra low cost• New connector

– 100 pins, 1.27 mm pin pitch

• Target market: peripherals, e.g. printers• Status: APPROVED

– 1 Rank x16, 2 Rank x8, 1 Rank x8, 2 Rank x16

What is On the Horizon?

• DDR2 Mini-RDIMM

• 4 Rank DDR1 RDIMM

• 4 Rank DDR2 RDIMM, SO-DIMM, & Micro-DIMM

• Fully Buffered DIMM

• DDR3 modules

DDR2 Mini-RDIMM• New to DDR2… no DDR1

equivalent• Supports x72 (ECC) and

registered• Larger than SO-DIMM: 82 mm• New socket required

– 244 pins, 0.6 mm pin pitch

• Target market: blade server

4 Rank DDR1 RDIMM

• Doubles per-slot memory capacity to 4GB!• Takes advantage of existing chip selects• Requires additional signals routed on motherboard

• PC-3200 with a single slot

CS3#

CS0#CS1#CS2#

MemoryController

MemoryController

CS3#

CS0#CS1#CS2#

4 Rank DDR2 RDIMM

• Similar to DDR1 4 Rank• Supports address parity• Requires additional signals routed on motherboard

• PC2-4200 with a single slot… headroom to PC2-5300? PC2-6400?

CS3#

CS0#CS1#CS2#

MemoryController

MemoryController

CS3#

CS0#CS1#CS2#

Ad. Parity Ad. Parity

4 Rank DDR2 SO-DIMM, Micro-DIMM

• Highest capacity modules with 4 ranks of x8– 1GB using 256Mb (32 DRAMs)– 2GB using 512Mb– 4GB using 1Gb

• Lowest power modules with 4 ranks of x16– 512MB using 256Mb (16 DRAMs)– 1GB using 512Mb– 2GB using 1Gb– Estimated 20-25% reduction in power over x8

• Higher performance– Twice as many open pages possible

• Cost protection during density crossovers(like 512Mb1Gb)

Fully Buffered DIMM

Processor

DIMM

Problem - Stub Bus

DIMM

DIMM

DIMM

Each single sided DDR2-800 DIMM capable of 6.4 GB/s Four DIMMs capable of over 25 GB/s Bus Topology can not deliver the bandwidth to the application Stub bus only able to deliver the bandwidth of one DIMM Need headroom to support DDR3

FB-DIMM High Speed Channel

DDR3 Modules• Active development has begun• Performance to 1.6Gbps per pin• Point to point, point to 2 points• Fly-by buses with controller de-skew

Address, Command,

Clocks

Data,

Strobes

Controller

DR

AM

DR

AM

Keeping Them Straight

New label: 1GB 2Rx8 PC2-5300U-444 11-A1

1GB = Total module capacity

2Rx8 = Number of ranks of memory & chip width

PC2-5300 = Speed grade in MB/s across DIMM

U = Module type (unbuffered, registered, etc.)

444 = CAS latency–tRCD–tRP performance grade

11 = SPD revision (encoding + additions)

A1 = Standard board layout and revision

2004 Modules Summary

• DDR1 development continues– PC-3200 speed bumps, 32b DIMM, 4 Rank RDIMM

• DDR2 modules ready to roll out– UDIMM, RDIMM, SO-DIMM, Micro-DIMM

• DDR2 Speed Grades finalized– PC2-3200, PC2-4200, PC2-5300, PC2-6400

• New DDR2 modules in development– Mini-RDIMM, 4 rank R-/SO-/Micro-DIMM, FB-DIMM

• DDR3 modules development begun• New DIMM labels assist user identification

Thank You___

Q & A