
DS1554 256k, Nonvolatile, Y2K-Compliant Timekeeping RAM
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Figure 1. Block Diagram
Table 1. Operating Modes
VCC
CE
OE
WE
DQ0–DQ7
MODE
POWER
VIH
X
High-Z
Deselect
Standby
VIL
X
VIL
DIN
Write
Active
VIL
VIH
DOUT
Read
Active
VCC > VPF
VIL
VIH
High-Z
Read
Active
VSO < VCC <VPF
X
High-Z
Deselect
CMOS Standby
VCC <VSO < VPF
X
High-Z
Data Retention
Battery Current
Maxim
DS1554