DS1553 Maxim, DS1553 Datasheet - Page 6

• Manufacturer Part Number: DS1553
• Description: The DS1553 is a full-function, year-2000-compliant (Y2KC) real-time clock/calendar (RTC) with an RTC alarm, watchdog timer, power-on reset, battery monitor, and "8k x 8 nonvolatile static RAM (NV SRAM)
• Manufacturer: Maxim

CLOCK OPERATIONS
Table 2 and the following paragraphs describe the operation of RTC, alarm, and watchdog functions.
Table 2. Register Map
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
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
ADDRESS
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
1FFDh
1FFCh
1FFBh
1FFAh
1FFFh
1FFEh
1FF9h
1FF8h
1FF7h
1FF6h
1FF5h
1FF4h
1FF3h
1FF2h
1FF1h
1FF0h
OSC
bit set to 1.
WDS
AM4
AM3
AM2
AM1
OSC
WF
AE
B
W
Y
X
X
X
X
X
7
BMB
AF
FT
B
X
X
X
Y
Y
Y
Y
R
4
6
10 Year
10 Seconds
10 Seconds
10 Minutes
10 Minutes
BMB3 BMB2
ABE
B
X
X
10 Century
Y
0
10 Hours
5
10 Hour
10 Date
10 Date
10 M
BLF
DATA
B
Y
Y
X
4
BMB
B
X
Y
Y
1
0
6 of 20
3
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
BMB
Seconds
Seconds
Minutes
Century
Minutes
B
Month
Y
Y
0
Hours
0
Hour
Year
Date
Date
2
Day
RB
B
Y
Y
1
0
1
RB0
B
Y
Y
0
0
Alarm Minutes
Alarm Seconds
FUNCTION/RANGE
Alarm Hours
Alarm Date
Watchdog
Interrupts
Minutes
Seconds
Control
Unused
Month
Flags
Hour
Year
Date
Day
OSC
bit is the
00-99
01-12
01-31
01-07
00-23
00-59
00-59
00-39
01-31
00-23
00-59
00-59
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