Harman Kardon AVR 2600, Service Manual

Page: 161 / 229

7
Revision 1.9
256M Double Data Rate Synchronous DRAM
A3S56D30ETP
A3S56D40ETP
BASIC FUNCTIONS
The A3S56D30/40ETP 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.
/CLK
CLK
Chip Select : L=select, H=deselect
/CS
define basic commands
Command /RAS
Command
/CAS
Command
/WE
Refresh Option @refresh command
CKE
Precharge Option @precharge or read/write command
A10
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 including bank address are generated
internally. After this command, the banks are precharged automatically.
AVR3600
harman/kardon
161