DS1553 Datasheet, PDF (6/20 Pages) Maxim Integrated Products – 64kB, Nonvolatile, Year-2000-Compliant Timekeeping RAM

DS1553 64kB, Nonvolatile, Year-2000-Compliant Timekeeping RAM
CLOCK OPERATIONS
Table 2 and the following paragraphs describe the operation of RTC, alarm, and watchdog functions.
Table 2. Register Map
ADDRESS
B₇
1FFFh
B₆
B₅
10 Year
DATA
B₄
B₃
B₂
B₁ B₀
Year
1FFEh
X
X
X 10 M
Month
1FFDh
X
X
10 Date
Date
1FFCh
X
FT
X
X
X
Day
1FFBh
X
X
10 Hour
Hour
1FFAh
X
10 Minutes
Minutes
1FF9h OSC
10 Seconds
Seconds
1FF8h
W
R
10 Century
Century
1FF7h
WDS
BMB
4
BMB3
BMB2
BMB
1
BMB
0
RB
1
RB0
1FF6h
AE
Y ABE
Y
Y
Y YY
1FF5h AM4 Y
10 Date
Date
1FF4h AM3 Y
10 Hours
Hours
1FF3h AM2
10 Minutes
Minutes
1FF2h AM1
10 Seconds
Seconds
1FF1h
Y
Y
Y
Y
Y
Y YY
1FF0h WF AF
0
BLF 0
0
00
FUNCTION/RANGE
Year
Month
Date
Day
Hour
Minutes
Seconds
Control
00-99
01-12
01-31
01-07
00-23
00-59
00-59
00-39
Watchdog
Interrupts
Alarm Date
Alarm Hours
Alarm Minutes
Alarm Seconds
Unused
Flags
01-31
00-23
00-59
00-59
—
—
X = Unused, Read/Writable Under Write and Read Bit Control
FT = Frequency Test Bit
OSC = Oscillator Start/Stop Bit
W = Write Bit
R = Read Bit
WDS = Watchdog Steering Bit
BMB0–BMB4 = Watchdog Multiplier Bits
RB0–RB1 = Watchdog Resolution Bits
AE = Alarm Flag Enable
Y = Unused, Read/Writable Without Write and Read Bit Control
ABE = Alarm in Battery-Backup Mode Enable
AM1–AM4 = Alarm Mask Bits
WF = Watchdog Flag
AF = Alarm Flag
0 = 0 Read Only
BLF = Battery Low Flag
CLOCK OSCILLATOR CONTROL
The clock oscillator may be stopped at any time. To increase the shelf life of the backup lithium battery
source, the oscillator can be turned off to minimize current drain from the battery. The OSC bit is the
MSB of the Seconds register (B7 of 1FF9h). Setting it to 1 stops the oscillator; setting it to 0 starts the
oscillator. The DS1553 is shipped from Dallas Semiconductor with the clock oscillator turned off, with
the OSC bit set to 1.
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