DS1343_1112 Datasheet, PDF (1/20 Pages) Maxim Integrated Products – Low-Current SPI/3-Wire RTCs

19-5801; Rev 1; 12/11
Low-Current SPI/3-Wire RTCs
General Description
The DS1343/DS1344 low-current real-time clocks (RTCs)
are timekeeping devices that provide an extremely low
standby current, permitting longer life from a backup
supply source. The devices also support high-ESR
crystals, broadening the pool of usable crystals for the
devices. 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 24-hour or
12-hour format with an AM/PM indicator.
Address and data are transferred serially through an
SPI or 3-wire interface. Two programmable time-of-day
alarms are provided. Each alarm can generate an inter-
rupt on a combination of seconds, minutes, hours, and
day. Don’t-care states can be inserted into one or more
fields if it is desired for them to be ignored for the alarm
condition. The time-of-day alarms can be programmed
to assert two different interrupt outputs, or they can be
combined to assert one common interrupt output. Both
interrupt outputs operate when the device is powered by
either VCC or VBAT.
The devices are available in a lead-free/RoHS-compliant,
20-pin TSSOP or 14-pin TDFN package, and support a
-40°C to +85°C extended industrial temperature range.
Medical
Handheld Devices
Telematics
Embedded Timestamping
Applications
Features
S Low Timekeeping Current of 250nA (typ)
S Compatible with Crystal ESR Up to 100kI
S Versions Available to Support Either 6pF or
12.5pF Crystals
S RTC Counts Seconds, Minutes, Hours, Day, Date,
Month, and Year with Leap Year Compensation
Valid Through 2099
S Power-Fail and Switch Circuitry
S Three Operating Voltages
1.8V ±5%
3.0V±10%
3.3V ±10%
S Trickle-Charge Capability
S Maintain Time Down to 1.15V (typ)
S Support Motorola SPI Modes 1 and 3, or Standard
3-Wire Interface
S Burst Mode for Reading/Writing Successive
Addresses in Clock/RAM
S 96-Byte Battery-Backed NV RAM for Data Storage
S Two Time-of-Day Alarms with Two Interrupt
Outputs
S Industrial Temperature Range
S 20-Pin TSSOP or 14-Pin TDFN Package
S Underwriters Laboratories (UL) Recognized
Typical Operating Circuit
VCC
Ordering Information appears at end of data sheet.
RPU
INT
RST
μP
3-WIRE
PORT
VCC
INT0
X1
PF
INT1
CE
DS1343
DS1344
X2
SCLK
SDI
SDO
VBAT
SERMODE GND
NOTE: SHOWN IN 3-WIRE I/O CONFIGURATION.
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