W364M72V-100SBM White Electronic Designs, W364M72V-100SBM Datasheet - Page 6

• Manufacturer Part Number: W364M72V-100SBM
• Manufacturer: White Electronic Designs

Specifications of W364M72V-100SBM

• Lead Free Status / Rohs Status: Supplier Unconfirmed

WRITE BURST MODE
When M9 = 0, the burst length programmed via M0-M2 applies
to both READ and WRITE bursts; when M9 = 1, the programmed
burst length applies to READ bursts, but write accesses are single-
location (nonburst) accesses.
COMMANDS
The Truth Table provides a quick reference of available com mands.
This is followed by a written de scrip tion of each com mand. Three
additional Truth Tables appear following the Op er a tion section;
these tables provide current state/next state information.
COMMAND INHIBIT
The COMMAND INHIBIT function pre vents new commands from
being executed by the SDRAM, regardless of whether the CLK
signal is enabled. The SDRAM is effectively de se lect ed. Op er a tions
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 pre vents
unwanted commands from being registered dur ing idle or wait
states. Op er a tions already in progress are not affected.
LOAD MODE REGISTER
The Mode Register is loaded via inputs A0-11 (A12 should be driven
low). See Mode Reg is ter heading in the Register Defi ni tion sec tion.
The LOAD MODE REGISTER command can only be issued when
all banks are idle, and a sub se quent ex e cut able com mand cannot
be issued until t
Microsemi Corporation reserves the right to change products or specifi cations without notice.
February 2011 © 2011 Microsemi Corporation. All rights reserved.
Rev. 4
MRD
is met.
Command
Command
CLK
CLK
I/O
I/O
READ
READ
T0
T0
CAS Latency = 2
FIGURE 4 – CAS LATENCY
T1
T1
NOP
NOP
CAS Latency = 3
t
LZ
t
AC
T2
T2
NOP
NOP
6
t
D
LZ
t
OUT
OH
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,
BA1 inputs se lects the bank, and the address pro vid ed on inputs
A0-12 selects the row. This row remains active (or open) for
ac cess es until a PRECHARGE com mand 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, BA1 inputs selects the bank,
and the address provided on inputs A0-9, A11 se lects the starting
column location. The value on input A10 de ter mines 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 is not selected, the row will remain
open for subsequent ac cess es. Read data appears on the I/Os
sub ject to the logic level on the DQM inputs two clocks earlier. If a
given DQM signal was registered HIGH, the cor re spond ing I/Os
will be High-Z two clocks later; if the DQM signal was registered
LOW, the I/Os will provide valid data.
WRITE
The WRITE command is used to initiate a burst write access to
an active row. The value on the BA0, BA1 inputs selects the bank,
and the address provided on inputs A0-9, A11 se lects the starting
column location. The value on input A10 de ter mines 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 sub se quent accesses. Input data appearing on
t
AC
T3
T3
NOP
D
t
OUT
OH
T4
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