DS1558W Maxim Integrated Products, DS1558W Datasheet - Page 7

• Manufacturer Part Number: DS1558W
• Description: IC RTC W/NV RAM 3.3V 48-LQFP
• Manufacturer: Maxim Integrated Products
• Type: Watchdog Timer/NVSRAMr

Specifications of DS1558W

• Time Format: HH:MM:SS (24 hr)
• Date Format: YY-MM-DD-dd
• Interface: Parallel
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Memory Size: -

CLOCK OPERATIONS
Table 2 and the following paragraphs describe the operation of the RTC, alarm, and watchdog functions.
Table 2. DS1558 REGISTER MAP
CLOCK OSCILLATOR CONTROL
The oscillator can be turned off to minimi
the seconds register (B7 of 7FFF9h). Setting
oscillator. The initial state of
bit should be enabled.
monitoring the
OSCILLATOR STARTUP TIME
Oscillator startup times are highly dependent upon crystal characteristics and layout. High ESR and
excessive capacitive loads are the major contributors to long startup times. A circuit using a crystal with
the recommended characteristics and following the recommended layout usually starts within 1 second.
ADDR
X = Unused, Read/Writeable Under Write and
FT = Frequency Test Bit
OSC = Oscillator Start/Stop Bit
W = Write Bit
R = Read Bit
WEN = Watchdog Enable Bit
BMB0–BMB4 = Watchdog Multiplier Bits
RB0–RB1 = Watchdog Resolution Bits
7FFFD
7FFF
7FFF
7FFFAh
7FFF
7FFFF
7FFF9h
7FFF
7FFF7h
7FFF6h
7FFF5h
7FF
7FFF3h
7FFF2h
7FFF1h
7FFF0h
F4h
Eh
Ch
Bh
ESS
8h
h
h
WDS
AM4
A
A
A
OSC
W
AE
B
W
IRQ
X
X
X
X
X
Y
M3
M2
M1
7
F
/FT pin for 512Hz.
BMB4
AF
FT
B
X
X
X
R
Y
Y
Y
Y
Oscillator operation and fre
6
10 YEAR
10 SECONDS
1
10 MINUTES
1
0 SE
0 M
BMB3
OSC
ABE
10 CENTURY
INUT
B
X
X
CO
Y
1
0
10 HOUR
10 DATE
10 DATE
5
0 HOURS
NDS
Read Bit Control
is not guaranteed. When power is applied for the first time, the
ES
BMB2
10 M
BL
B
DATA
X
Y
Y
4
F
ze current drain from
BMB1
OSC
B
X
Y
Y
0
7 of 18
3
to a 1 stops the oscillator; setting to a 0 starts the
quency can be verified by se
AE = Alarm Flag Enable
Y = Unused, Read/Writeable Without Write and Read Bit Control
ABE = Alarm in Backup-Battery Mode Enable
AM1–AM4 = Alarm Mask Bits
WF = Watchdog Flag
AF = Alarm Flag
0 = Reads as a 0 and Cannot Be Changed
BLF = Batter
BMB0
CENTURY
SECONDS
SECONDS
MINUTES
MINUTES
MONTH
HOURS
B
Y
Y
YEAR
HOUR
DATE
DATE
0
2
DAY
RB1
y Lo
B
Y
Y
0
1
the battery. The
w Flag
RB0
B
Y
Y
0
0
ALARM SECONDS
ALARM MINUTES
ALARM HOURS
ALARM DATE
INTERRUPTS
WATCHDOG
FUNCTION/RAN
CONTROL
SECONDS
MINUTES
UNUSED
MONTH
FLAGS
HOUR
YEAR
DATE
OSC
DAY
tting the FT
bit is the MSB of
GE
00–99
01–12
01–31
01–07
00–23
00–59
00–59
00–39
01–31
00–23
00–59
00–59
bit and
—
—
—
—
OSC