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5.1 Intel 915PM North Bridge(5)
DDR / DDR2 Common Signals
Signal Name
Type
Description
SM_CK[1:0],
SM_CK[4:3]
O
SSTL1.8/2
SDRAM Differential Clock:
The crossing of the positive edge of SM_CKx and the negative edge
of its complement SM_CKx# are used to sample the command and
control signals on the SDRAM.
SM_CK[0:1]
and its complement
SM_CK[1:0]#
signal make a
differential clock pair output.
Single channel mode: Route to SO-DIMM 0
Dual channel mode: Route to SO-DIMM A
SM_CK[4:3]
and its complement
SM_CK[4:3]#
signal make a
differential clock pair output.
Single channel mode: Route to SO-DIMM 1
Dual channel mode: Route to SO-DIMM B
NOT
E:
SM_CK2
and
SM_CK5
are reserved and not supported.
SM_CK[1:0]#,
SM_CK[4:3]#
O
SSTL1.8/2
SDRAM Inverted Differential Clock:
These are the complementary Differential DDR2 Clock signals.
NOT
E:
SM_CK2#
and
SM_CK5#
are reserved and not supported.
SM_CS[3:0]#
O
SSTL1.8/2
Chip Select:
(1 per Rank):
These signals select particular SDRAM components during the active
state. There is one Chip Select for each SDRAM rank
SM_CS[1:0]#
:
Single channel mode: Route to SO-DIMM 0
Dual channel mode: Route to SO-DIMM A
SM_CS[3:2]#
:
Single channel mode: Route to SO-DIMM 1
Dual channel mode: Route to SO-DIMM B
SM_CKE[3:0]
O
SSTL1.8/2
Clock Enable:
(1 per Rank):
SM_CKE[3:0] is used:
.To initialize the SDRAMs during power-up
.To power-down SDRAM ranks
. To place all SDRAM ranks into and out of self-refresh during STR.
SM_CKE[1:0]:
Single channel mode: Route to SO-DIMM 0
Dual channel mode: Route to SO-DIMM A
SM_CKE[3:2]:
Single channel mode: Route to SO-DIMM 1
Dual channel mode: Route to SO-DIMM B
DDR / DDR2 Common Signals (Continued)
Signal Name
Type
Description
SM_ODT[3:0]
O
SSTL1.8/2
On Die Termination: Active Termination Contro
l. (DDR2 only)
SM_ODT[1:0]:
Single channel mode: Route to SO-DIMM 0
Dual channel mode: Route to SO-DIMM A
Signal Description
The crossing of the positive edge of SM_CKx and the negative edge
of its
complement SM_CKx# are used to sample the command and control
SM_CK[0:1]
and its complement
SM_CK[1:0]#
signal make a
differential
SM_CK[4:3]
and its complement
SM_CK[4:3]#
signal make a
differential
NOT
E:
SM_CK2
and
SM_CK5
are reserved and not supported.
These are the complementary Differential DDR2 Clock signals.
NOT
E:
SM_CK2#
and
SM_CK5#
are reserved and not supported.
These signals select particular SDRAM components during the active
To place all SDRAM ranks into and out of self-refresh during STR.
On Die Termination: Active Termination Contro
l. (DDR2 only)
SM_ODT[3:2]:
Single channel mode: Route to SO-DIMM 1
Dual channel mode: Route to SO-DIMM B
DDR: Leave as no connects. Not used for DDR devices.
DDR2: On-die termination for DDR2 devices.
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