X20C05
AUTOSTORE Feature
The AUTOSTORE feature automatically saves the con-
tents of the X20C05’s RAM to the on-board bit-for-bit
shadow E PROM 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.
toautomaticallyperformastoreoperationwheneverV
CC
CC
falls below the AUTOSTORE threshold (V
). V
ASTH
2
must remain above the AUTOSTORE Cycle End Volt-
age (V ) for the duration of the store cycle (t ).
ASEND
ASTO
The detailed timing for this feature is illustrated in the
AUTOSTORE timing diagram, below. Once the
AUTOSTOREcycleisinitiated, allotherdevicefunctions
are inhibited.
The AUTOSTORE instruction (EAS) to the SDP register
setstheAUTOSTOREenablelatch,allowingtheX20C05
AUTOSTORE CYCLE Timing Diagrams
V
5
4
3
2
1
CC
V
ASTH
AUTOSTORE CYCLE IN PROGRESS
V
ASEND
t
ASTO
STORE TIME
TIME (ms)
CC
V
t
V
ASTH
0V
t
PUR
t
PUR
ASTO
AS
3827 FHD F14
AUTOSTORE CYCLE LIMITS
Symbol
X20C05
Parameter
Min.
Max.
Units
t
AUTOSTORE Cycle Time
2.5
4.3
ms
V
ASTO
V
V
AUTOSTORE Threshold Voltage
AUTOSTORE Cycle End Voltage
4.0
3.5
ASTH
V
ASEND
3827 PGM T15
12
XICOR [ XICOR INC. ]
