GLT5640L32 Datasheet, PDF (17/49 Pages) List of Unclassifed Manufacturers – CMOS Synchronous DRAM 2M x 32 SDRAM

G-LINK
COMMANDS
ADVANCED
GLT5640L32
CMOS Synchronous DRAM
COMMAND INHIBIT
The COMMAND INHIBIT function prevents new commands from being executed by the SDRAM, regardless of whether the CLK signal is
enabled. The SDRAM is effectively deselected. Operations already in progress are not affected.
NO OPERATION (NOP)
The NO OPERATION (NOP) command is used to perform a NOP to an SDRAM which is selected (CS# is LOW). This prevents unwanted
commands from being registered during idle or wait states. Operations already in progress are not affected.
LOAD MODE REGISTER
The Mode Register is loaded via inputs A0-A10. See Mode Register heading in the Register Definition sec-tion. The LOAD MODE REGISTER
command can only be issued when all banks are idle, and a subsequent executable command cannot be issued until t MRD is met.
ACTIVE
The ACTIVE command is used to open (or activate) a row in a particular bank for a subsequent access. The value on the BA0 and BA1 inputs
selects the bank, and the address provided on inputs A0-A10 selects the row. This row remains active (or open) for accesses until a
PRECHARGE command is issued to that bank. A PRECHARGE command must be issued before opening a different row in the same bank.
READ
The READ command is used to initiate a burst read access to an active row. The value on the BA0 and BA1 (B1) inputs selects the bank, and
the address provided on inputs A0-A7 selects the starting column location. The value on input A10 determines whether or not AUTO
PRECHARGE is used. If AUTO PRECHARGE is selected, the row being accessed will be precharged at the end of the READ burst; if AUTO
PRECHARGE iis not selected, the row will remain open for subsequent accesses. Read data appears on the DQs subject to the logic level on
the DQM inputs two clocks earlier. If a given DQMx signal was registered HIGH, the corresponding DQs will be High-Z two clocks later; if the
DQMx signal was registered LOW, the corresponding DQs will provide valid data. DQM0 corresponds to DQ0-DQ7, DQM1 corresponds to DQ8-
DQ15, DQM2 corresponds to DQ16-DQ23 and DQM3 corresponds to DQ24-DQ31.
WRITE
The WRITE command is used to initiate a burst write access to an active row. The value on the BA0 and BA1 inputs selects the bank, and the
address provided on inputs A0-A7 selects the starting column location. The value on input A10 determines whether or not AUTO PRECHARGE
is used. If AUTO PRECHARGE is selected, the row being accessed will be precharged at the end of the WRITE burst; if AUTO PRECHARGE is
not selected, the row will remain open for subsequent accesses. Input data appearing on the DQs is written to the memory array subject to the
DQM input logic level appearing coincident with the data. If a given DQM signal is registered LOW, the corresponding data will be written to
memory; if the DQM signal is registered HIGH, the corresponding data inputs will be ignored, and a WRITE will not be executed to that
byte/column location.
PRECHARGE
The PRECHARGE command is used to deactivate the open row in a particular bank or the open row in all banks. The bank(s) will be available
for a subsequent row access a specified time ( tRP) after the PRECHARGE command is issued. Input A10 determines whether one or all banks
are to be precharged, and in the case where only one bank is to be precharged, inputs BA0 and BA1 select the bank. Otherwise BA0 and BA1
are treated as “Don’t Care.” Once a bank has been precharged, it is in the idle state and must be activated prior to any READ or WRITE
commands being issued to that bank.
G-Link Technology Corp.
17
Dec 2003 Rev.0.3