Feb.2000
MITSUBISHI LSIs
MITSUBISHI ELECTRIC
SDRAM (Rev.1.1)
Single Data Rate
M2V56S20/ 30/ 40/ TP -6, -7, -8
256M Synchronous DRAM
5
BASIC FUNCTIONS
The M2V56S20/30/40TP provides basic functions, bank (row) activate, burst read / write, bank (row)
precharge, and auto / self refresh. Each command is defined by control signals of /RAS, /CAS and /WE at
CLK rising edge. In addition to 3 signals, /CS ,CKE and A10 are used as chip select, refresh option, and
precharge option, respectively. To know the detailed definition of commands, please see the command
truth table.
Activate (ACT) [/RAS =L, /CAS =/WE =H]
ACT command activates a row in an idle bank indicated by BA.
Read (READ) [/RAS =H, /CAS =L, /WE =H]
READ command starts burst read from the active bank indicated by BA. First output data appears after
/CAS latency. When A10 =H at this command, the bank is deactivated after the burst read (auto-
precharge,
READA
)
Write (WRITE) [/RAS =H, /CAS =/WE =L]
WRITE command starts burst write to the active bank indicated by BA. Total data length to be written
is set by burst length. When A10 =H at this command, the bank is deactivated after the burst write (auto-
precharge,
WRITEA
).
Precharge (PRE) [/RAS =L, /CAS =H, /WE =L]
PRE command deactivates the active bank indicated by BA. This command also terminates burst read
/write operation. When A10 =H at this command, all banks are deactivated (precharge all,
PREA
).
Auto-Refresh (REFA) [/RAS =/CAS =L, /WE =CKE =H]
REFA command starts auto-refresh cycle. Refresh address are generated internally. After this
command, the banks are precharged automatically.
/CS
Chip Select : L=select, H=deselect
/RAS
Command
/CAS
Command
/WE
Command
CKE
Refresh Option @refresh command
A10
Precharge Option @precharge or read/write command
CLK
define basic commands