AVAILAB
LE
DS1337
I
2
C Serial Real-Time Clock
www.maxim-ic.com
GENERAL DESCRIPTION
FEATURES
Real-Time Clock (RTC) Counts Seconds,
Minutes, Hours, Day, Date, Month, and Year
with Leap-Year Compensation Valid Up to
2100
Available in a Surface-Mount Package with an
Integrated Crystal (DS1337C)
I
2
C Serial Interface
Two Time-of-Day Alarms
Oscillator Stop Flag
Programmable Square-Wave Output
Defaults to 32kHz on Power-Up
Available in 8-Pin DIP, SO, or
SOP
-40C to +85C Operating Temperature Range
The DS1337 serial real-time clock is a low-power
clock/calendar with two programmable time-of-day
alarms and a programmable square-wave output.
Address and data are transferred serially through an
I
2
C bus. The clock/calendar provides seconds,
minutes, hours, day, date, month, and year
information. The date at the end of the month is
automatically adjusted for months with fewer than 31
days, including corrections for leap year. The clock
operates in either the 24-hour or 12-hour format with
AM/PM indicator.
The device is fully accessible through the serial
interface while V
CC
is between 1.8V and 5.5V. I
2
C
operation is not guaranteed below 1.8V.
Timekeeping operation is maintained with V
CC
as low
as 1.3V.
APPLICATIONS
Handhelds (GPS, POS Terminal, MP3 Player)
Consumer Electronics (Set-Top Box, VCR/Digital
Recording)
Office Equipment (Fax/Printer, Copier)
Medical (Glucometer, Medicine Dispenser)
Telecommunications (Router, Switch, Server)
Other (Utility Meter, Vending Machine,
Diagrams
Functional
Thermostat,
Modem)
ORDERING INFORMATION
PART
DS1337+
DS1337S+
DS1337U+
DS1337C#
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 DIP (300 mils)
8 SO (150 mils)
8
SOP
16 SO (300 mils)
TOP
MARK†
DS1337
DS1337
1337
DS1337C
TYPICAL OPERATING CIRCUIT
+ Denotes a lead(Pb)-free/RoHS-compliant device.
# Denotes a RoHS-compliant device that may include lead that is
exempt under the RoHS requirements. The lead finish is JESD97
category e3, and is compatible with both lead-based and lead-free
soldering processes.
†
A “+” anywhere on the top mark denotes a lead-free device. A
“#” denotes a RoHS-compliant device.
Pin Configurations appear at end of data sheet.
Pin Configurations appear at end of data sheet.
Functional Diagrams continued at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-4652; 7/09
DS1337 I
2
C Serial Real-Time Clock
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground…………………………………………………………...…-0.3V to +6.0V
Operating Temperature Range (Noncondensing)………………………………………………………….-40°C to +85°C
Storage Temperature Range………………………………………………………………………………..-55°C to +125°C
Soldering Temperature…………………………………………………………See IPC/JEDEC J-STD-020 Specification
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only,
and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is
not implied. Exposure to the absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED DC OPERATING CONDITIONS
(T
A
= -40°C to +85°C)
PARAMETER
V
CC
Supply Voltage
SYMBOL
V
CC
V
CCT
V
IH
V
IL
CONDITIONS
Full operation
Timekeeping (Note
5)
SCL, SDA
INTA,
SQW/INTB
-0.3
MIN
1.8
1.3
0.7 x V
CC
TYP
3.3
MAX
5.5
1.8
V
CC
+ 0.3
5.5
+0.3 x V
CC
UNITS
V
V
V
V
Logic 1
Logic 0
DC ELECTRICAL CHARACTERISTICS—Full Operation
(V
CC
= 1.8V to 5.5V,
T
A
= -40°C to +85°C.) (Note 1)
PARAMETER
Input Leakage
I/O Leakage
Logic 0 Output (V
OL
= 0.4V)
Active Supply Current
Standby Current
SYMBOL
I
LI
I
LO
I
OL
I
CCA
I
CCS
CONDITIONS
(Note 2)
(Note 3)
(Note 3)
(Note 4)
(Notes 5, 6)
MIN
-1
-1
TYP
MAX
+1
+1
3
150
1.5
UNITS
A
A
mA
A
A
DC ELECTRICAL CHARACTERISTICS--Timekeeping
(V
CC
= 1.3V to 1.8V,
T
A
= -40°C to +85°C.) (Note 1)
PARAMETER
Timekeeping Current
(Oscillator Enabled)
Data-Retention Current
(Oscillator Disabled)
SYMBOL
I
CCTOSC
I
CCTDDR
CONDITIONS
(Notes 5, 7, 8, 9)
(Notes 5, 9)
MIN
TYP
425
MAX
600
100
UNITS
nA
nA
DS1337 I
2
C Serial Real-Time Clock
AC ELECTRICAL CHARACTERISTICS
(V
CC
= 1.8V to 5.5V, T
A
= -40°C to +85°C.) (Note 1)
PARAMETER
SCL Clock Frequency
Bus Free Time Between a
STOP and START Condition
Hold Time (Repeated)
START Condition (Note 10)
LOW Period of SCL Clock
HIGH Period of SCL Clock
Setup Time for a Repeated
START Condition
Data Hold Time
(Notes 11, 12)
Data Setup Time (Note 13)
Rise Time of Both SDA and
SCL Signals (Note 14)
Fall Time of Both SDA and
SCL Signals (Note 14)
Setup Time for STOP
Condition
Capacitive Load for Each Bus
Line
I/O Capacitance (SDA, SCL)
Oscillator Stop Flag (OSF)
Delay
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Note 9:
Note 10:
Note 11:
Note 12:
Note 13:
SYMBOL
f
SCL
t
BUF
t
HD:STA
t
LOW
t
HIGH
t
SU:STA
t
HD:DAT
t
SU:DAT
t
R
t
F
t
SU:STO
C
B
C
I/O
t
OSF
CONDITIONS
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
(Note 14)
(Note 15)
MIN
100
0
1.3
4.7
0.6
4.0
1.3
4.7
0.6
4.0
0.6
4.7
0
0
100
250
20 + 0.1C
B
20 + 0.1C
B
20 + 0.1C
B
20 + 0.1C
B
0.6
4.0
TYP
MAX
400
100
UNITS
kHz
s
s
s
s
s
0.9
s
ns
300
1000
300
300
ns
ns
s
400
10
100
pF
pF
ms
Limits at -40°C are guaranteed by design and are not production tested.
SCL only.
SDA,
INTA,
and SQW/INTB.
I
CCA
—SCL clocking at max frequency = 400kHz, V
IL
= 0.0V, V
IH
= V
CC.
Specified with the I C bus inactive, V
IL
= 0.0V, V
IH
= V
CC.
SQW enabled.
Specified with the SQW function disabled by setting INTCN = 1.
Using recommended crystal on X1 and X2.
The device is fully accessible when 1.8
V
CC
5.5V. Time and date are maintained when 1.3V
V
CC
1.8V.
After this period, the first clock pulse is generated
A device must internally provide a hold time of at least 300ns for the SDA signal (referred to the V
IHMIN
of the SCL signal) to
bridge the undefined region of the falling edge of SCL.
The maximum t
HD:DAT
need only be met if the device does not stretch the LOW period (t
LOW
) of the SCL signal.
A fast-mode device can be used in a standard-mode system, but the requirement t
SU:DAT
to 250ns must then be met. This is
automatically the case if the device does not stretch the LOW period of the SCL signal. If such a device does stretch the LOW
period of the SCL signal, it must output the next data bit to the SDA line t
R max
+ t
SU:DAT
= 1000 + 250 = 1250ns before the SCL
line is released.
C
B
—total capacitance of one bus line in pF.
Guaranteed by design. Not production tested.
2
Note 14:
Note 15:
DS1337 I
2
C Serial Real-Time Clock
Note 16:
The parameter t
OSF
is the period of time that the oscillator must be stopped for the OSF bit to be set over the
voltage range of V
CC(MIN)
≤
V
CC
≤
V
CC(MAX).
.
TYPICAL OPERATING CHARACTERISTICS
(V
CC
= 3.3V, T
A
= +25°C, unless otherwise noted.)
I
CCTOSC
1000
900
800
700
600
500
400
300
1.3
1.8
2.3
I
CC
vs. V
CC
I
CCS
I
CCA
vs. V
CC
125
INTCN = 0
(Squarew ave on)
100
I
CC
(nA)
I
CC
(uA)
INTCN = 1
(Squarew ave off)
75
50
25
0
2.8
3.3 3.8
V
CC
(V)
4.3
4.8
5.3
1.8
2.3
2.8
3.3
3.8
V
CC
(V)
4.3
4.8
5.3
700
650
I
CCS
vs. Temperature
V
CC
= 3.0V
OSCILLATOR FREQUENCY vs. V
CC
32768.35
32768.3
32768.25
FREQUENCY (Hz)
32768.2
INTCN = 0
(Squarew ave on)
600
550
500
450
400
350
-40.0
INTCN = 1
(Squarew ave off)
I
CC
(nA)
32768.15
32768.1
32768.05
32768
1.3
1.8
2.3
2.8 3.3
V
CC
(V)
3.8
4.3
4.8
-20.0
0.0
20.0
40.0
V
CC
(V)
60.0
80.0
DS1337 I
2
C Serial Real-Time Clock
PIN DESCRIPTION
8
1
PIN
16
—
NAME
X1
FUNCTION
Connections for a Standard 32.768kHz Quartz Crystal. The internal
oscillator circuitry is designed for operation with a crystal having a specified
load capacitance (C
L
) of 6pF. For more information about crystal selection
and crystal layout considerations, refer to
Application Note 58: Crystal
Considerations with Dallas Real-Time Clocks.
An external 32.768kHz
oscillator can also drive the DS1337. In this configuration, the X1 pin is
connected to the external oscillator signal and the X2 pin is floated.
Interrupt Output. When enabled,
INTA
is asserted low when the
time/day/date matches the values set in the alarm registers. This pin is an
open-drain output and requires an external pullup resistor.
The pull up
voltage may be up to 5.5V, regardless of the voltage on V
CC
. If not used, this pin
may be left floating.
2
—
X2
3
14
INTA
4
5
6
7
8
—
15
16
1
2
3
4–13
GND
SDA
SCL
SQW/INTB
V
CC
N.C.
Ground. DC power is provided to the device on this pin.
Serial Data Input/Output. SDA is the input/output pin for the I
2
C serial
interface. The SDA pin is open-drain output and requires an external pullup
resistor.
Serial Clock Input. SCL is used to synchronize data movement on the serial
interface.
Square-Wave/Interrupt Output. Programmable square-wave or interrupt
output signal. It is an open-drain output and requires an external pullup
resistor.
The pull up voltage may be up to 5.5V, regardless of the voltage on V
CC
.
If not used, this pin may be left floating.
DC Power. DC power is provided to the device on this pin.
No Connect. These pins are not connected internally, but must be
grounded for proper operation.
TIMING DIAGRAM
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