The DS1341/DS1342 low-current real-time clocks (RTCs)
are timekeeping devices that provide an extremely low
standby current, which permits longer life from a power
supply. The DS1341/DS1342 support high-ESR crystals,
which broaden the pool of usable crystals for the devices.
The DS1341 uses a 6pF crystal, while the DS1342 uses
a 12.5pF crystal. These devices are accessed through
an I
2
C serial interface. Other features include two time-
of-day alarms, two interrupt outputs, a programmable
square-wave output, and a serial bus timeout mechanism.
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 24hr or 12hr format with an
AM/PM indicator.
The DS1341/DS1342 also include an input for synchroni-
zation. When a reference clock (e.g., 60Hz power line or
GPS 1PPS) is present at the CLKIN pin and the enable
external clock input bit (ECLK) is set to 1, the DS1341/
DS1342 RTCs are frequency-locked to the external clock
and the clock accuracy is determined by the external
source. In case of external clock failure, the clock is
switched to the crystal oscillator.
The devices are available in lead(Pb)-free/RoHS-
compliant, 8-pin µSOP or TDFN packages. The devices
support a -40°C to +85°C extended temperature range.
Features
● Low Timekeeping Current of 250nA (typ)
● Compatible with Crystal ESR Up to 100kΩ
● Use Crystals with C
L
= 6pF (DS1341) or
C
L
= 12.5pF (DS1342)
● +1.8V to +5.5V Operating Voltage Range
● Maintain Time Down to +1.15V (typ)
● Fast (400kHz) I
2
C Interface
● Bus Timeout for Lockup-Free Operation
● RTC Counts Seconds, Minutes, Hours, Day, Date,
Month, and Year with Leap Year Compensation Valid
Through 2099
● External Clock Source for Synchronization Clock
Reference (e.g., 32kHz, 50Hz/60Hz Power Line,
GPS 1PPS)
● Two Time-of-Day Alarms with Two Interrupt Outputs
● Programmable Square-Wave Output
● Industrial Temperature Range
● Small 8-Pin μSOP or TDFN Packages
Applications
● Medical
● Point of Sale (POS)
● Telematics
● Portable Instruments
● Portable Audio
Ordering Information
PART
DS1341U+
DS1341U+T&R
DS1341T+
DS1341T+T&R
DS1342U+
DS1342U+T&R
DS1342T+
DS1342T+T&R
TEMP RANGE
-40ºC to +85ºC
-40ºC to +85ºC
-40ºC to +85ºC
-40ºC to +85ºC
-40ºC to +85ºC
-40ºC to +85ºC
-40ºC to +85ºC
-40ºC to +85ºC
PIN-
PACKAGE
8 µSOP
8 µSOP
8 TDFN-EP*
8 TDFN-EP*
8 µSOP
8 µSOP
8 TDFN-EP*
8 TDFN-EP*
OSC C
L
(pF)
6
6
6
6
12.5
12.5
12.5
12.5
Typical Operating Circuit
V
CC
V
CC
R
PU
R
PU
R
PU
SCL
SDA
CLKIN/INTA
V
CC
X1
CPU
SQW/INTB
X2
DS1341/DS1342
GND
+Denotes
a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
*EP
= Exposed pad.
19-4998; Rev 3; 4/15
DS1341/DS1342
Low-Current I
2
C RTCs for High-ESR Crystals
Absolute Maximum Ratings
Voltage Range on Any Pin Relative to Ground ....-0.3V to +6.0V
Operating Temperature Range ........................... -40°C to +85°C
Junction Temperature Maximum .....................................+150°C
Storage Temperature Range ............................ -55°C to +125°C
Lead Temperature (soldering, 10s) ................................. +300°C
Soldering Temperature (reflow) .......................................+260°C
Package Thermal Characteristics
(Note 1)
µSOP
Junction-to-Ambient Thermal Resistance (θ
JA
) .....206.3°C/W
Junction-to-Case Thermal Resistance (θ
JC
) ...............42°C/W
TDFN
Junction-to-Ambient Thermal Resistance (θ
JA
) ..........41°C/W
Junction-to-Case Thermal Resistance (θ
JC
) .................8°C/W
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to
www.maximintegrated.com/thermal-tutorial.
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 absolute maximum rating conditions for extended periods may affect
device reliability.
DC Electrical Characteristics
(V
CC
= +1.8V to +5.5V, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
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