DS1557 Maxim, DS1557 Datasheet - Page 5

• Manufacturer Part Number: DS1557
• Description: The DS1557 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 512k x 8 nonvolatile static RAM
• Manufacturer: Maxim

CLOCK OPERATIONS
Table 2 and the following paragraphs describe the operation of RTC, alarm, and watchdog functions.
Table 2. Register Map
ADDRESS
X = Unused, Read/Writeable Under Write and Read Bit Control
Y = Unused, Read/Writeable Without Write and Read Bit Control
OSC = Oscillator Start/Stop Bit
W = Write Bit
R = Read Bit
WDS = Watchdog Steering Bit
BMB0 to BMB4 = Watchdog Multiplier Bits
RB0 to RB1 = Watchdog Resolution Bits
7FFFDh
7FFFCh
7FFFBh
7FFFAh
7FFFEh
7FFFFh
7FFF9h
7FFF8h
7FFF7h
7FFF6h
7FFF5h
7FFF4h
7FFF3h
7FFF2h
7FFF1h
7FFF0h
WDS
AM4
AM3
AM2
AM1
OSC
WF
AE
B
W
X
X
X
X
X
Y
7
BMB4
AF
FT
B
X
X
X
Y
Y
Y
Y
R
6
10 Year
10 Seconds
10 Seconds
10 Minutes
10 Minutes
BMB3
Abe
B
X
X
Y
0
10 Century
5
10 Hours
10 Hour
10 Date
10 Date
BMB2
Month
BLF
B
10
DATA
X
Y
Y
4
BMB1
B
X
Y
Y
0
5 of 17
3
AE = Alarm Flag Enable
FT = Frequency Test Bit
ABE = Alarm in Battery-BackUp Mode Enable
AM1 to AM4 = Alarm Mask Bits
WF = Watchdog Flag
AF = Alarm Flag
0 = 0 (Read Only)
BLF = Battery Low Flag
BMB0
Seconds
Seconds
Minutes
Century
Minutes
B
Y
Y
Month
0
Hours
Hour
Year
Date
Date
2
Day
RB1
B
Y
Y
0
1
RB0
B
Y
Y
0
0
Alarm Minutes
Alarm Seconds
Alarm Hours
FUNCTION/RANGE
Alarm Date
Watchdog
Interrupts
Minutes
Seconds
Control
Unused
Month
Flags
Hour
Year
Date
Day
00-99
01-12
01-31
01-07
00-23
00-59
00-59
00-39
01-31
00-23
00-59
00-59