Extremely Accurate I2C-Integrated RTC/TXO/Crystal

The DS3231 is a low-cost, extremely accurate I2C real-
time clock (RTC) with an integrated temperature-
compensated crystal oscillator (TCXO) and crystal. The
device incorporates a battery input, and maintains accu-
rate timekeeping when main power to the device is inter-
rupted. The integration of the crystal resonator enhances
the long-term accuracy of the device as well as reduces
the piece-part count in a manufacturing line. The DS3231
is available in commercial and industrial temperature
ranges, and is offered in a 16-pin, 300-mil SO package.
The RTC maintains 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 an AM/PM indicator. Two programmable time-of-
day alarms and a programmable square-wave output
are provided. Address and data are transferred serially
through an I2C bidirectional bus.
A precision temperature-compensated voltage refer-
ence and comparator circuit monitors the status of VCC
to detect power failures, to provide a reset output, and
to automatically switch to the backup supply when nec-
essary. Additionally, the RST pin is monitored as a
pushbutton input for generating a reset externally.