X20C17
AUTOSTORE Feature
The X20C17 automatically initiates a nonvolatile store
cycle whenever V falls below the AUTOSTORE
CC
The AUTOSTORE feature automatically saves the
contents of the X20C17’s static RAM to the on-board
bit-for-bit shadow E2PROM at power-down. This circuitry
insures that no data is lost during accidental power-
downs or general system crashes, and is ideal for
microprocessor caching systems, embedded software
systems, and general system back-up memory.
threshold voltage (V
). V
must remain above
ASTH
CC
the AUTOSTORE Cycle End Voltage (V
) for the
ASEND
duration of the store cycle (t
). The detailed timing
ASTO
for this feature is illustrated in the AUTOSTORE timing
diagram, below. Once the AUTOSTORE cycle is initi-
ated, all other device functions are inhibited.
AUTOSTORE CYCLE Timing Diagram and Suggested AUTOSTORE Implementation Circuit
V
CC
V
5
4
3
2
1
CC
V
≤ 0.3V
F
V
V
ASTH
Autostore Cycle in Progress
ASEND
V
CC
t
ASTO
Store Time
X20C17
22µF
Time (Ms)
AUTOSTORE CYCLE LIMITS
X20C17
Symbol
Parameter
AUTOSTORE Cycle Time
Min.
Max.
2.5
Units
ms
V
(5)
t
ASTO
V
AUTOSTORE Threshold Voltage
AUTOSTORE Cycle End Voltage
4.0
3.5
4.3
ASTH
(5)
V
V
ASEND
Notes: (5) t
and V
are periodically sampled and not 100% tested.
ASEND
ASTO
Characteristics subject to change without notice. 8 of 12
XICOR [ XICOR INC. ]
