HYB18T256324F–[16/20/22]
256-Mbit DDR SGRAM
Pin Configuration
Data Sheet
20
Rev. 1.11, 04-2005
10292004-DOXT-FS0U
2.4.2
If there is more than one bank activated in the Graphics
SDRAM, some commands can be performed in parallel
due to the chip’s multibank architecture. The following
table defines for which commands such a scheme is
possible. All other transitions are illegal. Notes 1-11
define the start and end of the actions belonging to a
Function Truth Table for more than one Activated Bank
submitted command. This table is based on the
assumption that there are no other actions ongoing on
bank n or bank m. If there are any actions ongoing on a
third bank t
RRD
, t
RTW
and t
WTR
have to be taken always
into account.
1. Action ACTIVATE starts with issuing the command
and ends after t
RCD
2. Action WRITE starts with issuing the command and
ends t
WR
after the first pos. edge of CLK following
the last falling WDQS edge; exept for READ,
READ/A. WRITE, WRITE/A ends
t
WTR
after the first
pos. edge of CLK following the last falling WDQS
edge.
3. Action WRITE/A starts with issuing the command
and ends t
WR
after the first positive edge of CLK
following the last falling WDQS edge; exept for
READ, READ/A. WRITE, WRITE/A ends t
WTR
after
the first pos. edge of CLK following the last falling
WDQS edge.
4. Action READ starts with issuing the command and
ends with the first positive edge of CLK following the
last falling edge of RDQS
5. Action READ/A starts with issuing the command
and ends with the first positive edge of CLK
following the last falling edge of RDQS
6. Action PRECHARGE and PRECHARGE ALL start
with issuing the command and ends after t
RP
7. During POWER DOWN and SELF REFRESH only
the EXIT commands are allowed
8. Action AUTO REFRESH starts with issuing the
command and ends after t
RFC
9. Actions MODE REGISTER SET and EXTENDED
MODE REGISTER SET start with issuing the
command and ends after t
MRD
10.Action POWER DOWN EXIT starts with issuing the
command and ends after t
XPN
11.Action SELF REFRESH EXIT starts with issuing the
command and ends after t
XSC
12.During action ACTIVATE an ACT command on
another bank is allowed considering t
RRD
, a PRE
command on another bank is allowed any time.
WR, WR/A, RD and RD/A are always allowed.
13.During action WRITE an ACT or a PRE command
on another bank is allowed any time. A new WR or
WR/A command on another bank must be
separated by at least one NOP from the ongoing
WRITE. RD or RD/A are not allowed before t
WTR
is
met.
Table 7
Current
State
ACTIVE
Function Truth Table I
ongoing action on bank n
possible action in parallel on bank m
ACTIVATE
1
WRITE
2
WRITE/A
3
READ
4
READ/A
5
PRECHARGE
6
PRECHARGE ALL
6
POWER DOWN ENTRY
7
ACTIVATE
1
POWER DOWN ENTRY
7
AUTO REFRESH
8
SELF REFRESH ENTRY
7
MODE REGISTER SET (MRS)
9
EXTENDED MRS
9
POWER DOWN EXIT
10
SELF REFRESH EXIT
11
ACT, PRE, WRITE, WRITE/A, READ, READ/A
12
ACT, PRE, WRITE, WRITE/A, READ, READ/A
13
ACT, PRE, WRITE, WRITE/A, READ
14
ACT, PRE, WRITE, WRITE/A, READ, READ/A
15
ACT, PRE, WRITE, WRITE/A, READ, READ/A
15
ACT, PRE, WRITE, WRITE/A, READ, READ/A
12
-
-
ACT
-
-
-
-
-
-
-
IDLE
POWER DOWN
SELF REFRESH