Signal Description
R
26 Intel
®
82925X/82925XE MCH Datasheet
2.2 DDR2 DRAM Channel A Interface
Signal Name Type Description
SCLK_A[5:0] O
SSTL-1.8
SDRAM Differential Clock: (3 per DIMM). SCLK_Ax and its
complement SCLK_Ax# signal make a differential clock pair output. The
crossing of the positive edge of SCLK_Ax and the negative edge of its
complement SCLK_Ax# are used to sample the command and control
signals on the SDRAM.
SCLK_A[5:0]# O
SSTL-1.8
SDRAM Complementary Differential Clock: (3 per DIMM) These are
the complementary differential DDR2 Clock signals.
SCS_A[3:0]# O
SSTL-1.8
Chip Select: (1 per Rank) These signals select particular SDRAM
components during the active state. There is one chip select for each
SDRAM rank.
SMA_A[13:0] O
SSTL-1.8
Memory Address: These signals are used to provide the multiplexed
row and column address to the SDRAM
SBS_A[2:0] O
SSTL-1.8
Bank Select: These signals define which banks are selected within each
SDRAM rank
DDR2: 1-Gb technology is 8 banks.
SRAS_A# O
SSTL-1.8
Row Address Strobe: This signal is used with SCAS_A# and SWE_A#
(along with SCS_A#) to define the SDRAM commands.
SCAS_A# O
SSTL-1.8
Column Address Strobe: This signal is used with SRAS_A# and
SWE_A# (along with SCS_A#) to define the SDRAM commands.
SWE_A# O
SSTL-1.8
Write Enable: This signal is used with SCAS_A# and SRAS_A# (along
with SCS_A#) to define the SDRAM commands.
SDQ_A[63:0] I/O
SSTL-1.8
2x
Data Lines: SDQ_A signals interface to the SDRAM data bus.
SDM_A[7:0] O
SSTL-1.8
2X
Data Mask: When activated during writes, the corresponding data
groups in the SDRAM are masked. There is one SDM_Ax signal for
every data byte lane.
SCB_A[7:0]
(Intel
®
82925X
Only)
I/O
SSTL-1.8
2X
ECC Check Byte: These signals require a 6-layer board to be routed.
SDQS_A[8:0]
(82925X MCH)
SDQS_A[7:0]
(82925XE
MCH)
I/O
SSTL-1.8
2x
Data Strobes: For DDR2, SDQS_Ax and its complement SDQS_Ax#
signal make up a differential strobe pair. The data is captured at the
crossing point of SDQS_Ax and its complement SDQS_Ax# during read
and write transactions.
SDQS_A[8:0]#
(82925X MCH)
SDQS_A[7:0]#
(82925XE
MCH)
I/O
SSTL-1.8
2x
Data Strobe Complements: These signals are the complementary
DDR2 strobe signals.
SCKE_A[3:0] O
SSTL-1.8
Clock Enable: (1 per Rank) SACKE is used to initialize the SDRAMs
during power-up, to power-down SDRAM ranks, and to place all SDRAM
ranks into and out of self-refresh during Suspend-to-RAM.
SODT_A[3:0] O
SSTL-1.8
On Die Termination: Active On-die Termination Control signals for
DDR2 devices.
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