STK12C68-S35 Cypress Semiconductor Corp, STK12C68-S35 Datasheet - Page 10

• Manufacturer Part Number: STK12C68-S35
• Manufacturer: Cypress Semiconductor Corp
• Type: NVSRAMr

Specifications of STK12C68-S35

• Word Size: 8b
• Organization: 8Kx8
• Density: 64Kb
• Interface Type: Parallel
• Access Time (max): 35ns
• Operating Supply Voltage (typ): 5V
• Package Type: SOIC
• Operating Temperature Classification: Commercial
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 4.5V
• Operating Temp Range: 0C to 70C
• Pin Count: 28
• Mounting: Surface Mount
• Supply Current: 75mA
• Lead Free Status / RoHS Status: Not Compliant

STK12C68, STK12C68-5 (SMD5962-94599)
Document Control #ML0008 Rev 2.0
SOFTWARE NONVOLATILE RECALL
A software
of
ware
the following sequence of
tions must be performed:
Internally,
SRAM
information is transferred into the
the t
ready for
operation in no way alters the data in the Nonvolatile
Elements. The nonvolatile data can be recalled an
unlimited number of times.
AutoStore MODE
The STK12C68, STK12C68-5 can be powered in
one of three modes.
During normal AutoStore operation, the STK12C68,
STK12C68-5 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
Figure 2 shows the proper connection of capacitors
for automatic store operation. A charge storage
capacitor having a capacity of between 68μF and
220μF (± 20%) rated at 6V should be provided.
In system power mode, both V
nected to the + 5V power supply without the 68μF
capacitor. In this mode the AutoStore function of the
STK12C68, STK12C68-5 will operate on the stored
system charge as power goes down. The user must,
however, guarantee that V
3.6V during the 10ms
AutoStore INHIBIT MODE
If an automatic
then V
1. Read address
2. Read address
3. Read address
4. Read address
5. Read address
6. Read address
READ
RECALL
June, 2008
STORE
CC
data is cleared, and second, the nonvolatile
operation. After power up, when the voltage
STORE
operations in a manner similar to the soft-
can be tied to ground and + 5V applied to
CAP
READ
RECALL
cycle time the
RECALL
pin drops below V
initiation. To initiate the
STORE
and
operation.
is a two-step procedure. First, the
cycle is initiated with a sequence
0000 (hex)
1555 (hex)
0AAA (hex)
1FFF (hex)
10F0 (hex)
0F0E (hex)
WRITE
STORE
on power loss is not required,
SRAM
E
CC
operations. The
controlled
cycle.
does not drop below
CAP
CAP
CC
SWITCH
will once again be
Valid READ
Valid READ
Valid READ
Valid READ
Valid READ
Initiate RECALL cycle
and V
SRAM
pin from V
pin. This stored
RECALL
CC
, the part will
READ
CAP
to charge a
cells. After
are con-
RECALL
opera-
CC
cycle,
and
10
V
which the AutoStore function is disabled. If the
STK12C68, STK12C68-5 is operated in this configu-
ration, references to V
throughout this data sheet. In this mode,
operations may be triggered through software con-
trol or the HSB pin. To enable or disable AutoStore
using an IO port pin, see “PREVENTING STORES”
on page 11.
In order to prevent unneeded
automatic
externally driving HSB low will be ignored unless at
least one
most recent
ated
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.
If the power supply drops faster than 20 μs/volt
before V
should be inserted between V
ply to avoid momentary excess of current between
V
CAP
cc
*If HSB is not used, it should be left unconnected.
and V
(Figure 3). This is the AutoStore Inhibit mode, in
STORE
CC
WRITE
cap
Figure 3: AutoStore Inhibit Mode
reaches V
STORE
WRITE
.
STORE
Figure 2: AutoStore Mode
cycles are performed regardless of
+
operation has taken place since the
s as well as those initiated by
operation has taken place. An
or
SWITCH
CC
14
RECALL
14
1
1
should be changed to V
, then a 2.2 ohm resistor
15
28
27
26
28
27
26
15
CC
cycle. Software initi-
and the system sup-
STORE
operations,
STORE
CAP