mt18htf25672fy-667 Micron Semiconductor Products, mt18htf25672fy-667 Datasheet - Page 7

• Manufacturer Part Number: mt18htf25672fy-667
• Description: 1gb, 2gb X72, Sr 240-pin Ddr2 Sdram Fbdimm
• Manufacturer: Micron Semiconductor Products

General Description
Advanced Memory Buffer
pdf: 09005aef81a2f214/source: 09005aef81a2f22d
HTF18C64_128_256x72F.fm - Rev. B 9/07 EN
The Micron FBDIMM adheres to the currently proposed industry specifications for
FBDIMMs. The following specifications contain detailed information on FBDIMM
design, interfaces, and theory of operation, and are listed here for the system designers’
convenience. Refer to the JEDEC Web site for available specifications.
• FBDIMM Design Specification – pending JEDEC approval
• FBDIMM: Architecture and Protocol – JESD206
• FBDIMM: Advanced Memory Buffer (AMB) – JESD82-20
• Design for Test, Design for Validation (DFx) Specification
• Serial Presence-Detect (SPD) for Fully Buffered DIMM – JEDEC Standard No. 21-C
The MT18HTF12872F and MT18HTF25672F DDR2 SDRAM modules are a high-band-
width, large-capacity channel solution that have a narrow host interface. FBDIMMs use
DDR2 SDRAM devices isolated from the channel behind an AMB buffer on the
FBDIMM. Memory device capacity remains high, and total memory capacity scales with
DDR2 SDRAM bit density.
As shown in Figure 2 on page 5, the FBDIMM channel provides a communication path
from a host controller to an array of DDR2 SDRAM devices, with the DDR2 SDRAM
devices buffered behind an AMB device. The physical isolation of the DDR2 SDRAM
devices from the channel enhances the communication path and significantly increases
the reliability and availability of the memory subsystem.
The AMB isolates the DDR2 SDRAM devices from the channel. This single-chip AMB
component, located in the center of each FBDIMM, acts as a repeater and buffer for all
signals and commands exchanged between the host controller and DDR2 SDRAM
devices, including data input and output. The AMB communicates with the host
controller and adjacent FBDIMMs on a system board using an industry-standard, high-
speed, differential, 1.5V, point-to-point interface. The AMB also enables buffering of
memory traffic to support large memory capacities. Refer to the JEDEC JESD82-20 spec-
ification for further information.
page 4.1.2.7-1
1GB, 2GB (x72, SR) 240-Pin DDR2 SDRAM FBDIMM
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Micron Technology, Inc., reserves the right to change products or specifications without notice.
General Description
©2005 Micron Technology, Inc. All rights reserved.