X20C16
The second method of storing data is with the
AUTOSTORE command. When enable, data is auto-
matically stored for the RAM into the EEPROM array
whenever V
CC
falls below the preset Autostore thresh-
old. This feature is enabled by performing the first two
steps for the software store with the command combi-
nation being 555[H]/CC[H].
The AUTOSTORE feature is disable by issuing the
three step command sequence with the command
combination being 555[H]/CD[H]. The AUTOSTORE
feature will also be reset if V
CC
falls below the power-
up reset threshold (approximately 3.5V) and is then
raised back into the operation range.
Write Protection
The X20C16 supports two methods of protecting the
nonvolatile data.
– If after power-up the AUTOSTORE feature is not
enabled, no AUTOSTORE can occur.
– V
CC
Sense—All functions are inhibited when V
CC
is
3.0V typical.
The following symbol table provides a key to under-
standing the conventions used in the device timing dia-
grams. The diagrams should be used in conjunction
with the device timing specifications to determine
actual device operation and perfomance, as well as
device suitability for user’s application.
SYMBOL TABLE
WAVEFORM
INPUTS
Must be
steady
OUTPUTS
Will be
steady
ro
O
bs
ol
et
e
P
du
May change
from LOW
to HIGH
May change
from HIGH
to LOW
Don’t Care:
Changes
Allowed
N/A
Will change
from LOW
to HIGH
Will change
from HIGH
to LOW
Changing:
State Not
Known
Center Line
is High
Impedance
REV 1.0 6/21/00
www.xicor.com
Characteristics subject to change without notice.
ct
4 of 21
XICOR [ XICOR INC. ]
