STK14C88-M Simtek, STK14C88-M Datasheet - Page 9

• Manufacturer Part Number: STK14C88-M
• Description: 32K x 8 AUTOSTORE nvSRAM QUANTUM TRAP CMOS NONVOLATILE STATIC RAM
• Manufacturer: Simtek

SOFTWARE NONVOLATILE RECALL
A software
of
ware
the following sequence of E controlled
tions must be performed:
Internally,
SRAM
information is transferred into the
the t
ready for
operation in no way alters the data in the
cells. The nonvolatile data can be recalled an unlim-
ited number of times.
AutoStore ™ OPERATION
The STK14C88-M can be powered in one of three
modes.
During
STK14C88-M will draw current from V
capacitor connected to the V
charge will be used by the chip to perform a single
STORE
on the V
automatically disconnect the V
initiate a
*If HSB is not used, it should be left unconnected.
April 1999
1. Read address
2. Read address
3. Read address
4. Read address
5. Read address
6. Read address
READ
Figure 2: AutoStore ™ Mode
RECALL
STORE
+
data is cleared, and second, the nonvolatile
operation. After power up, when the voltage
STORE
operations in a manner similar to the soft-
CAP
READ
normal
RECALL
cycle time the
RECALL
pin drops below V
initiation. To initiate the
1
16
and
operation.
10k
is a two-step procedure. First, the
cycle is initiated with a sequence
AutoStore ™
0E38 (hex)
31C7 (hex)
03E0 (hex)
3C1F (hex)
303F (hex)
0C63 (hex)
WRITE
32
31
30
17
SRAM
operations. The
CAP
CAP
SWITCH
will once again be
Valid READ
Valid READ
Valid READ
Valid READ
Valid READ
Initiate RECALL cycle
pin from V
SRAM
pin. This stored
operation,
CCX
RECALL
, the part will
READ
to charge a
Figure 3: System Power Mode
cells. After
EEPROM
RECALL
CCX
opera-
cycle,
and
the
1
16
5-51
32
31
30
17
Figure 2 shows the proper connection of capacitors
for automatic store operation. A charge storage
capacitor having a capacity of between 68 F and
220 F ( 20%) rated at 6V should be provided.
In system power mode (Figure 3), both V
V
the 100 F capacitor. In this mode the AutoStore ™
function of the STK14C88-M will operate on the
stored system charge as power goes down. The
user must, however, guarantee that V
drop below 3.6V during the 10ms
If an automatic
then V
V
mode, in which the AutoStore ™ function is disabled.
If the STK14C88-M is operated in this configuration,
references to V
throughout this data sheet. In this mode,
operations may be triggered through software con-
trol or the HSB pin. It is not permissable to change
between these three options “on the fly”.
In order to prevent unneeded
automatic
externally driving HSB low will be ignored unless at
least one
most recent
initiated
whether a
optional pull-up resistor is shown connected to HSB.
This can be used to signal the system that the
AutoStore ™ cycle is in progress.
CAP
CAP
are connected to the + 5V power supply without
(Figure 4). This is the AutoStore ™ Inhibit
CCX
STORE
WRITE
can be tied to ground and + 5V applied to
STORE
WRITE
STORE
STORE
cycles are performed regardless of
operation has taken place since the
CCX
s as well as those initiated by
operation has taken place. An
should be changed to V
or
on power loss is not required,
Figure 4: AutoStore ™
RECALL
Inhibit Mode
1
16
STORE
STK14C88-M
STORE
cycle. Software-
32
31
30
17
CCX
operations,
cycle.
does not
CCX
STORE
and
CAP