STK14D88_08 SIMTEK [Simtek Corporation], STK14D88_08 Datasheet - Page 13

• Manufacturer Part Number: STK14D88_08
• Description: 32Kx8 Autostore nvSRAM
• Manufacturer: SIMTEK [Simtek Corporation]

Document Control #ML0033 Rev 2.0
DATA PROTECTION
The STK14D88 protects data from corruption during
low-voltage conditions by inhibiting all externally
initiated STORE and WRITE operations. The low-
voltage condition is detected when V
If the STK14D88 is in a WRITE mode (both E and W
low) at power-up, after a RECALL, or after a
STORE, the WRITE will be inhibited until a negative
transition on E or W is detected. This protects
against inadvertent writes during power up or brown
out conditions.
BEST PRACTICES
nvSRAM products have been used effectively for
over 15 years. While ease-of-use is one of the prod-
uct’s main system values, experience gained work-
ing with hundreds of applications has resulted in the
following suggestions as best practices:
• The non-volatile cells in an nvSRAM are pro-
• Power up boot firmware routines should rewrite
• If autostore has been firmware disabled, it will not
grammed on the test floor during final test and
quality assurance. Incoming inspection routines
at customer or contract manufacturer’s sites will
sometimes reprogram these values. Final NV pat-
terns are typically repeating patterns of AA, 55,
00, FF, A5, or 5A. End product’s firmware should
not assume an NV array is in a set programmed
state. Routines that check memory content val-
ues to determine first time system configuration,
cold or warm boot status, etc. should always pro-
gram a unique NV pattern (e.g., complex 4-byte
pattern of 46 E6 49 53 hex or more random
bytes) as part of the final system manufacturing
test to ensure these system routines work consis-
tently.
the nvSRAM into the desired state (autostore
enabled, etc.). While the nvSRAM is shipped in a
preset state, best practice is to again rewrite the
nvSRAM into the desired state as a safeguard
against events that might flip the bit inadvertently
(program bugs, incoming inspection routines,
etc.).
reset to “autostore enabled” on every power
down event captured by the nvSRAM. The appli-
cation firmware should re-enable or re-disable
autostore on each reset sequence based on the
behavior desired.
Jan 2008
CC
<V
SWITCH
.
13
• The V
LOW AVERAGE ACTIVE POWER
CMOS technology provides the STK14D88 with the
benefit of power supply current that scales with
cycle time. Less current will be drawn as the mem-
ory cycle time becomes longer than 50 ns. Figure 4
shows the relationship between I
WRITE cycle time. Worst-case current consumption
is shown for commercial temperature range,
V
Only standby current is drawn when the chip is dis-
abled. The overall average current drawn by the
STK14D88 depends on the following items:
CC
includes a minimum and a maximum value size.
Best practice is to meet this requirement and not
exceed the max V
internal algorithm calculates V
based on this max Vcap value. Customers that
want to use a larger V
there is extra store charge and store time should
discuss their V
understand any impact on the V
at the end of a t
=3.6V, and chip enable at maximum frequency.
1
2
3
4
5
6
50
40
30
20
10
0
Figure 4 - Current vs. Cycle Time
cap
The duty cycle of chip enable
The overall cycle rate for operations
The ratio of READs to WRITEs
The operating temperature
The V
I/O Loading
value specified in this datasheet
cap
RECALL
50
CC
cap
Cycle Time (ns)
size selection with Simtek to
Level
100 150 200 300
value because the nvSRAM
period.
cap
value to make sure
STK14D88
cap
cap
CC
Writes
Reads
voltage level
charge time
and READ/