DS3231SN# Maxim Integrated Products, DS3231SN# Datasheet - Page 10

• Manufacturer Part Number: DS3231SN#
• Description: IC RTC W/TCXO 16-SOIC
• Manufacturer: Maxim Integrated Products
• Type: Clock/Calendar/TCXO/Crystalr

Specifications of DS3231SN#

• Time Format: HH:MM:SS (12/24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.300", 7.5mm Width)
• Function: Clock/Calendar/Battery Backup
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.3 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Rtc Bus Interface: Serial (I2C)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The temperature sensor, oscillator, and control logic
form the TCXO. The controller reads the output of the
on-chip temperature sensor and uses a lookup table to
determine the capacitance required, adds the aging
correction in AGE register, and then sets the capaci-
tance selection registers. New values, including
changes to the AGE register, are loaded only when a
change in the temperature value occurs, or when a
user-initiated temperature conversion is completed.
Temperature conversion occurs on initial application of
V
This function is provided by a temperature-compensat-
ed voltage reference and a comparator circuit that
monitors the V
the part is powered by V
but greater than V
If V
device is powered by V
To preserve the battery, the first time V
the device, the oscillator will not start up until V
exceeds V
the part. Typical oscillator startup time is less than one
second. Approximately 2 seconds after V
or a valid I
temperature measurement and applies the calculated
correction to the oscillator. Once the oscillator is run-
ning, it continues to run as long as a valid power
source is available (V
tinues to measure the temperature and correct the
oscillator frequency every 64 seconds.
On the first application of power (V
I
date registers are reset to 01/01/00 01 00:00:00
(MM/DD/YY DOW HH:MM:SS).
There are several modes of operation that affect the
amount of V
is powered by V
Extremely Accurate I
RTC/TCXO/Crystal
Table 1. Power Control
10
2
CC
C address is written to the part (V
CC
and once every 64 seconds afterwards.
V
V
V
V
SUPPLY CONDITION
____________________________________________________________________
CC
CC
CC
CC
is less than V
< V
< V
> V
> V
PF
2
PF
PF
PF
PF
BAT
C address is written, the device makes a
, or until a valid I
, V
, V
, V
, V
CC
CC
CC
CC
CC
current that is drawn. While the device
BAT
level. When V
BAT
< V
> V
< V
> V
CC
and the serial interface is active,
, the DS3231 is powered by V
BAT
BAT
BAT
BAT
PF
BAT
CC
or V
and is less than V
. See Table 1.
. When V
BAT
V
2
C address is written to
CC
BAT
), and the device con-
ACTIVE SUPPLY
CC
is greater than V
CC
BAT
Power Control
) or when a valid
BAT
32kHz TCXO
Operation
is less than V
), the time and
V
V
V
V
CC
BAT
CC
CC
CC
is applied to
is applied,
BAT
, the
2
CC
PF
CC
PF
C-Integrated
,
.
active battery current, I
interface is inactive, timekeeping current (I
includes the averaged temperature conversion current,
I
Considerations for Accurate Real-Time Clocks for
details). Temperature conversion current, I
specified since the system must be able to support the
periodic higher current pulse and still maintain a valid
voltage level. Data retention current, I
current drawn by the part when the oscillator is
stopped (EOSC = 1). This mode can be used to mini-
mize battery requirements for times when maintaining
time and date information is not necessary, e.g., while
the end system is waiting to be shipped to a customer.
The DS3231 provides for a pushbutton switch to be
connected to the RST output pin. When the DS3231 is
not in a reset cycle, it continuously monitors the RST
signal for a low going edge. If an edge transition is
detected, the DS3231 debounces the switch by pulling
the RST low. After the internal timer has expired
(PB
If the line is still low, the DS3231 continuously monitors
the line looking for a rising edge. Upon detecting
release, the DS3231 forces the RST pin low and holds it
low for t
RST is also used to indicate a power-fail condition.
When V
nal is generated, which forces the RST pin low. When
V
low for approximately 250ms (t
supply to stabilize. If the oscillator is not running (see
the Power Control section) when V
bypassed and RST immediately goes high. Assertion of
the RST output, whether by pushbutton or power-fail
detection, does not affect the internal operation of the
DS3231.
With the clock source from the TCXO, the RTC provides
seconds, minutes, hours, day, date, month, and year
information. The date at the end of the month is auto-
matically 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.
The clock provides two programmable time-of-day
alarms and a programmable square-wave output. The
INT/SQW pin either generates an interrupt due to alarm
condition or outputs a square-wave signal and the
selection is controlled by the bit INTCN.
BATTC
CC
DB
returns to a level above V
), the DS3231 continues to monitor the RST line.
, is used (refer to Application Note 3644: Power
RST
CC
.
is lower than V
Pushbutton Reset Function
BATA
PF
, is drawn. When the serial
, an internal power-fail sig-
REC
PF
, the RST pin is held
CC
Real-Time Clock
) to allow the power
is applied, t
BATTDR
BATT
BATTC
), which
, is the
REC
, is
is