X84161 Datasheet, PDF (5/18 Pages) Xicor Inc. – uPort Saver EEPROM

X84161/641/129
Low Power Operation
The device enters an idle state, which draws minimal cur-
rent when:
—an illegal sequence is entered. The following are the
more common illegal sequences:
• Read/Write/Write—any time
• Read/Write ‘1’—When writing the address or
writing data.
• Write ‘1’—when reading data
• Read/Read/Write ‘1’—after data is written to
device, but before entering the NV write sequence.
—the device powers-up;
—a nonvolatile write operation completes.
While a sequential read is in progress, the device
remains in an active state. This state draws more current
than the idle state, but not as much as during a read
itself. To go back to the lowest power condition, an invalid
condition is created by writing a ‘1’ after the last bit of a
read operation.
Write Protection
The following circuitry has been included to prevent
inadvertent nonvolatile writes:
—The internal Write Enable latch is reset upon
power-up.
—A reset sequence must be issued to set the internal
write enable latch before starting a write sequence.
—A special “start nonvolatile write” command sequence
is required to start a nonvolatile write cycle.
—The internal Write Enable latch is reset automatically
at the end of a nonvolatile write cycle.
—The internal Write Enable latch is reset and remains
reset as long as the WP pin is LOW, which blocks all
nonvolatile write cycles.
—The internal Write Enable latch resets on an invalid
write operation.
SYMBOL TABLE
WAVEFORM INPUTS
OUTPUTS
Must be
steady
Will be
steady
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
5