STK11C88-3
DEVICE OPERATION
The STK11C88-3 is a versatile 3.3V VCC memory
SOFTWARE NONVOLATILE STORE
chip that provides several modes of operation. The
STK11C88-3 can operate as a standard 32K x 8
SRAM. It has a 32K x 8 Nonvolatile Elements
shadow to which the SRAM information can be cop-
ied or from which the SRAM can be updated in non-
volatile mode.
The STK11C88-3 software STORE cycle is initiated
by executing sequential READ cycles from six spe-
cific address locations. During the STORE cycle an
erase of the previous nonvolatile data is first per-
formed, followed by a program of the nonvolatile
elements. The program operation copies the SRAM
data into nonvolatile memory. Once a STORE cycle
is initiated, further input and output are disabled until
the cycle is completed.
NOISE CONSIDERATIONS
Note that the STK11C88-3 is a high-speed memory
and so must have a high frequency bypass capaci-
tor of approximately 0.1μF connected between VCC
and VSS, using leads and traces that are as short as
possible. As with all high-speed CMOS ICs, normal
careful routing of power, ground and signals will
help prevent noise problems.
Because a sequence of reads from specific
addresses is used for STORE initiation, it is impor-
tant that no other READ or WRITE accesses inter-
vene in the sequence, or the sequence will be
aborted and no STORE or RECALL will take place.
To initiate the software STORE cycle, the following
READ sequence must be performed:
SRAM READ
The STK11C88-3 performs a READ cycle whenever
E and G are low and W is high. The address speci-
fied on pins A0-14 determines which of the 32,768
data bytes will be accessed. When the READ is initi-
ated by an address transition, the outputs will be
valid after a delay of tAVQV (READ cycle #1). If the
READ is initiated by E or G, the outputs will be valid
at tELQV or at tGLQV, whichever is later (READ cycle #2).
The data outputs will repeatedly respond to address
changes within the tAVQV access time without the need
for transitions on any control input pins, and will
remain valid until another address change or until E
or G is brought high.
1. Read address
2. Read address
3. Read address
4. Read address
5. Read address
6. Read address
0E38 (hex)
31C7 (hex)
03E0 (hex)
3C1F (hex)
303F (hex)
0FC0 (hex)
Valid READ
Valid READ
Valid READ
Valid READ
Valid READ
Initiate STORE cycle
The software sequence is clocked with E controlled
READs.
Once the sixth address in the sequence has been
entered, the STORE cycle will commence and the
chip will be disabled. It is important that READ cycles
and not WRITE cycles be used in the sequence,
although it is not necessary that G be low for the
sequence to be valid. After the tSTORE cycle time has
been fulfilled, the SRAM will again be activated for
READ and WRITE operation.
SRAM WRITE
A WRITE cycle is performed whenever E and W are
low. The address inputs must be stable prior to
entering the WRITE cycle and must remain stable
until either E or W goes high at the end of the cycle.
The data on the common I/O pins DQ0-7 will be writ-
ten into the memory if it is valid tDVWH before the end
of a W controlled WRITE or tDVEH before the end of an
E controlled WRITE.
SOFTWARE NONVOLATILE RECALL
A software RECALL cycle is initiated with a sequence
of READ operations in a manner similar to the soft-
ware STORE initiation. To initiate the RECALL cycle,
the following sequence of READ operations must be
performed:
It is recommended that G be kept high during the
entire WRITE cycle to avoid data bus contention on
the common I/O lines. If G is left low, internal circuitry
will turn off the output buffers tWLQZ after W goes low.
1. Read address
2. Read address
3. Read address
4. Read address
5. Read address
6. Read address
0E38 (hex)
31C7 (hex)
03E0 (hex)
3C1F (hex)
303F (hex)
0C63 (hex)
Valid READ
Valid READ
Valid READ
Valid READ
Valid READ
Initiate RECALL cycle
March 2006
7
Document Control # ML0013 rev 0.2
SIMTEK [ SIMTEK CORPORATION ]
