MT18HTF25672PY-667A2 Micron Technology Inc, MT18HTF25672PY-667A2 Datasheet - Page 6

• Manufacturer Part Number: MT18HTF25672PY-667A2
• Description: MODULE DDR2 2GB 240-DIMM
• Manufacturer: Micron Technology Inc

Specifications of MT18HTF25672PY-667A2

• Memory Type: DDR2 SDRAM
• Memory Size: 2GB
• Speed: 667MT/s
• Package / Case: 240-DIMM
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

General Description
Register and PLL Operation
Serial Presence-Detect Operation
PDF: 09005aef80e5e752/Source: 09005aef80e5e626
HTF18C64_128_256x72.fm - Rev. E 3/07 EN
The MT18HTF6472, MT18HTF12872(P), and MT18HTF25672(P) DDR2 SDRAM modules
are high-speed, CMOS, dynamic random-access 512MB, 1GB, and 2GB memory
modules organized in a x72 configuration. These DDR2 SDRAM modules use internally
configured 4-bank (256Mb, 512Mb) or 8-bank (1Gb) DDR2 SDRAM devices.
DDR2 SDRAM modules use double data rate architecture to achieve high-speed opera-
tion. The double data rate architecture is essentially a 4n-prefetch architecture with an
interface designed to transfer two data words per clock cycle at the I/O pins. A single
read or write access for the DDR2 SDRAM module effectively consists of a single 4n-bit-
wide, one-clock-cycle data transfer at the internal DRAM core and four corresponding
n-bit-wide, one-half-clock-cycle data transfers at the I/O pins.
A bidirectional data strobe (DQS, DQS#) is transmitted externally, along with data, for
use in data capture at the receiver. DQS is a strobe transmitted by the DDR2 SDRAM
device during READs and by the memory controller during WRITEs. DQS is edge-
aligned with data for READs and center-aligned with data for WRITEs.
DDR2 SDRAM modules operate from a differential clock (CK and CK#); the crossing of
CK going HIGH and CK# going LOW will be referred to as the positive edge of CK.
Commands are registered at every positive edge of CK. Input data is registered on both
edges of DQS, and output data is referenced to both edges of DQS, as well as to both
edges of CK.
DDR2 SDRAM modules operate in registered mode, where the command/address input
signals are latched in the registers on the rising clock edge and sent to the DDR2 SDRAM
devices on the following rising clock edge (data access is delayed by one clock cycle). A
phase-lock loop (PLL) on the module receives and redrives the differential clock signals
(CK, CK#) to the DDR2 SDRAM devices. The register(s) and PLL reduce address,
command, control, and clock signal loading by isolating DRAM from the system
controller. PLL clock timing is defined by JEDEC specifications and ensured by use of the
JEDEC clock reference board. Registered mode will add one clock cycle to CL.
DDR2 SDRAM modules incorporate serial presence-detect (SPD). The SPD function is
implemented using a 2,048-bit EEPROM. This nonvolatile storage device contains
256 bytes. The first 128 bytes can be programmed by Micron to identify the module type
and various SDRAM organizations and timing parameters. The remaining 128 bytes of
storage are available for use by the customer. System READ/WRITE operations between
the master (system logic) and the slave EEPROM device occur via a standard I
using the DIMM’s SCL (clock) and SDA (data) signals, together with SA (2:0), which
provide eight unique DIMM/EEPROM addresses. Write protect (WP) is tied to V
module, permanently disabling hardware write protect.
512MB, 1GB, 2GB (x72, ECC, SR) 240-Pin DDR2 SDRAM RDIMM
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Micron Technology, Inc., reserves the right to change products or specifications without notice.
General Description
©2003 Micron Technology, Inc. All rights reserved.
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