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Signal Definitions
(Continued)
CS1#
AK29
AH27
O
Chip Selects.
These bits are used to select
the module bank within system memory.
Each chip select corresponds to a specific
module bank. If CS# is high, the bank(s) do
not respond to RAS#, CAS#, and WE# until
the bank is selected again.
---
CS0#
P29
AL12
---
RASA#
N31
AK12
O
Row Address Strobe.
RAS#, CAS#, WE#
and CKE are encoded to support the different
SDRAM commands. RASA# is used with
CS[1:0]#.
---
CASA#
N30
AJ12
O
Column Address Strobe.
RAS#, CAS#,
WE# and CKE are encoded to support the
different SDRAM commands. CASA# is used
with CS[1:0]#.
---
WEA#
N29
AH12
O
Write Enable.
RAS#, CAS#, WE# and CKE
are encoded to support the different SDRAM
commands. WEA# is used with CS[1:0]#.
---
DQM7
AJ20
AB31
O
Data Mask Control Bits.
During memory
read cycles, these outputs control whether
SDRAM output buffers are driven on the MD
bus or not. All DQM signals are asserted dur-
ing read cycles.
During memory write cycles, these outputs
control whether or not MD data is written into
SDRAM.
DQM[7:0] connect directly to the [DQM7:0]
pins of each DIMM connector.
---
DQM6
AJ26
AG29
---
DQM5
AC30
AK21
---
DQM4
T28
AL15
---
DQM3
AJ21
AC31
---
DQM2
AL26
AG30
---
DQM1
AF31
AH23
---
DQM0
M31
AL11
---
CKEA
AC28
AL22
O
Clock Enable.
These signals are used to
enter Suspend/power-down mode. CKEA is
used with CS[1:0]#.
If CKE goes low when no read or write cycle
is in progress, the SDRAM enters power-
down mode. To ensure that SDRAM data
remains valid, the self-refresh command is
executed. To exit this mode, and return to
normal operation, drive CKE high.
These signals should have an external pull-
down resistor of 33 K
.
---
SDCLK3
AJ16
V29
O
SDRAM Clocks.
SDRAM uses these clocks
to sample all control, address, and data lines.
To ensure that the Suspend mode functions
correctly, SDCLK3 and SDCLK1 should be
used with CS1#. SDCLK2 and SDCLK0
should be used together with CS0#.
---
SDCLK2
AL20
AA28
---
SDCLK1
AH16
W29
---
SDCLK0
AC29
AJ21
---
SDCLK_IN
AJ30
AJ27
I
SDRAM Clock Input.
The SC2200 samples
the memory read data on this clock. Works in
conjunction with the SDCLK_OUT signal.
---
2.4.2
Memory Interface Signals (Continued)
Signal Name
Ball No.
Type
Description
Mux
EBGA
TEPBGA