X20C16 Datasheet, PDF (12/21 Pages) Xicor Inc. – High Speed AUTOSTORE™ NOVRAM

X20C16
AUTOSTORE Feature
The AUTOSTORE feature automatically saves the con-
tents of the X20C16’s static RAM to the on-board bit-for-
bit shadow E²PROM at power-down. This circuitry in-
sures that no data is lost during accidental power-downs
or general system crashes, and is ideal for microproces-
sor caching systems, embedded software systems, and
general system back-up memory.
AUTOSTORE CYCLE Timing Diagrams
The AUTOSTORE instruction (EAS) to the SDP register
sets the AUTOSTORE enable latch, allowing the X20C16
to automatically perform a store operation whenever
V_CC falls below the AUTOSTORE threshold (V_ASTH).
V_CC must remain above the AUTOSTORE Cycle End
Voltage (V_ASEND) for the duration of the store cycle
(t_ASTO). The detailed timing for this feature is illustrated
in the AUTOSTORE timing diagram, below. Once the
AUTOSTORE cycle is initiated, all other device func-
tions are inhibited.
5
VCC
4
AUTOSTORE CYCLE IN PROGRESS ^VASTH
VASEND
3
2 _tASTO
1
STORE TIME
TIME (ms)
VASTH
0V
AS
VCC
tPUR
tASTO
tPUR
AUTOSTORE CYCLE LIMITS
Symbol
t_ASTO
V_ASTH
V_ASEND
Parameter
AUTOSTORE Cycle Time
AUTOSTORE Threshold Voltage
AUTOSTORE Cycle End Voltage
Min.
4.0
3.5
X20C16
Max.
2.5
4.3
3826 FHD F14
Units
ms
V
V
3826 PGM T15
12