Rainbow Electronics DS1342 - Manual

_______________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Low-Current I 2 C RTCs for High-ESR Crystals
DS1341/DS1342
General Description
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 a lead(Pb)-free/RoHS-
compliant, 8-pin FSOP package. The devices support a
-40NC to +85NC extended temperature range.
Applications
Features
S
Low Timekeeping Current of 250nA (typ)
S
Compatible with Crystal ESR Up to 80kI
S
Use Crystals with C L = 6pF (DS1341) or
C L = 12.5pF (DS1342)
S
+1.8V to +5.5V Operating Voltage Range
S
Maintain Time Down to +1.15V (typ)
S
Fast (400kHz) I 2 C Interface
S
Bus Timeout for Lockup-Free Operation
S
RTC Counts Seconds, Minutes, Hours, Day, Date,
Month, and Year with Leap Year Compensation
Valid Through 2099
S
External Clock Source for Synchronization Clock
Reference (e.g., 32kHz, 50Hz/60Hz Power Line,
GPS 1PPS)
S
Two Time-of-Day Alarms with Two Interrupt
Outputs
S
Programmable Square-Wave Output
S
Industrial Temperature Range
S
Small, 8-Pin µSOP Package
19-4998; Rev 0; 10/09
Pin Configuration Typical Operating Circuit
Ordering Information
+Denotes a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
*Future product—contact factory for availability.
Medical
Point of Sale (POS)
Telematics Portable Instruments
Portable Audio
Automotive
µSOP
2 7 SQW/INTB X2
1 8 V CC X1
SCL CLKIN/INTA 3 6
SDA GND 4 5
DS1341
DS1342
TOP VIEW
+
DS1341/DS1342
SCL
SDA
CLKIN/INTA
SQW/INTB X1
X2
GND
V CC
V CC
R PU R PU R PU
CPU
V CC
PART TEMP RANGE
PIN-
PACKAGE OSC
C L (pF)
DS1341U+ -40NC to +85NC 8 FSOP 6
DS1341U+T&R -40NC to +85NC 8 FSOP 6
DS1342U+* -40NC to +85NC 8 FSOP 12.5
DS1342U+T&R* -40NC to +85NC 8 FSOP 12.5