DS3231SN#T&R ,Extremely Accurate I²C-Integrated RTC/TCXO/CrystalElectrical Characteristics(V = 2.3V to 5.5V, V = Active Supply (see Table 1), T = T to T , unless o ..
DS3231SN#T&R ,Extremely Accurate I²C-Integrated RTC/TCXO/CrystalFeatures2The DS3231 is a low-cost, extremely accurate I C ● Highly Accurate RTC Completely Manages ..
DS3232 ,Extremely Accurate I²C RTC with Integrated Crystal and SRAMApplications #Denotes a RoHS-compliant device that may include lead thatis exempt under the RoHS re ..
DS3232SN#T&R ,Extremely Accurate I²C RTC with Integrated Crystal and SRAMFeatures♦ Accuracy ±2ppm from 0°C to +40°CThe DS3232 is a low-cost temperature-compensated♦ Accurac ..
DS3234S# ,Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAMFeaturesThe DS3234 is a low-cost, extremely accurate SPI bus• Highly Accurate RTC with Integrated C ..
DS3234SN# ,Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAMApplicationsDS3234SN# -40°C to +85°C 20 SO DS3234SN Servers Utility Power MetersTelematics GPS #Den ..
EA2-4.5NU ,COMPACT AND LIGHTWEIGHTAPPLICATIONSElectronic switching systems, PBX, key telephone systems, automatic test equipment and ..
EA2-4.5T ,COMPACT AND LIGHTWEIGHTDATA SHEETMINIATURE SIGNAL RELAYEA2 SERIESCOMPACT AND LIGHTWEIGHTDESCRIPTIONThe EA2 series has red ..
EA25 ,COMPACT AND LIGHTWEIGHTFEATURESª Low power consumptionª Compact and light weightª 2 form c contact arrangementª Low magnet ..
EA2-5 ,COMPACT AND LIGHTWEIGHTFEATURESª Low power consumptionª Compact and light weightª 2 form c contact arrangementª Low magnet ..
EA2-5NJ ,COMPACT AND LIGHTWEIGHTDATA SHEETMINIATURE SIGNAL RELAYEA2 SERIESCOMPACT AND LIGHTWEIGHTDESCRIPTIONThe EA2 series has red ..
EA2-5NU ,COMPACT AND LIGHTWEIGHTAPPLICATIONSElectronic switching systems, PBX, key telephone systems, automatic test equipment and ..
DS3231SN#-DS3231SN#T&R
Extremely Accurate I²C-Integrated RTC/TCXO/Crystal
General DescriptionThe 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
accurate timekeeping when main power to the device
is interrupted. 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.precision temperature-compensated voltage reference
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 necessary.
Additionally, the RST pin is monitored as a pushbutton input for generating a μP reset.
Beneits and Features●Highly Accurate RTC Completely Manages All
Timekeeping Functions Real-Time Clock Counts Seconds, Minutes, Hours,
Date of the Month, Month, Day of the Week, and
Year, with Leap-Year Compensation Valid Up to 2100Accuracy ±2ppm from 0°C to +40°CAccuracy ±3.5ppm from -40°C to +85°CDigital Temp Sensor Output: ±3°C AccuracyRegister for Aging TrimRST Output/Pushbutton Reset Debounce InputTwo Time-of-Day AlarmsProgrammable Square-Wave Output Signal ●Simple Serial Interface Connects to Most
MicrocontrollersFast (400kHz) I2C Interface●Battery-Backup Input for Continuous TimekeepingLow Power Operation Extends Battery-Backup
Run Time3.3V Operation●Operating Temperature Ranges: Commercial
(0°C to +70°C) and Industrial (-40°C to +85°C)●Underwriters Laboratories® (UL) Recognized
ApplicationsUnderwriters Laboratories is a registered certification mark of
Underwriters Laboratories Inc.
Ordering Information and Pin Configuration appear at end of data
sheet.●Servers●Telematics●Utility Power Meters●GPS
DS3231VCC
SCL
RPU
RPU = tR/CB
RPU
INT/SQW
32kHz
VBAT
PUSHBUTTON
RESET
SDA
RST
N.C.
N.C.
N.C.
N.C.
VCC
VCC
GND
VCC
N.C.
N.C.
N.C.
N.C.
SCL
SDA
RST
DS3231Extremely Accurate I2C-Integrated
RTC/TCXO/Crystal
Typical Operating Circuit
Voltage Range on Any Pin Relative to Ground ....-0.3V to +6.0V
Junction-to-Ambient Thermal Resistance (θJA) (Note 1) 73°C/WJunction-to-Case Thermal Resistance (θJC) (Note 1) ....23°C/W
Operating Temperature Range
DS3231S ............................................................0°C to +70°C
DS3231SN ......................................................-40°C to +85°C
Junction Temperature ......................................................+125°C
Storage Temperature Range ..............................-40°C to +85°C
Lead Temperature (soldering, 10s) .................................+260°C
Soldering Temperature (reflow, 2 times max) .................+260°C
(see the Handling, PCB Layout, and Assembly section)
(TA = TMIN to TMAX, unless otherwise noted.) (Notes 2, 3)
(VCC = 2.3V to 5.5V, VCC = Active Supply (see Table 1), TA = TMIN to TMAX, unless otherwise noted.) (Typical values are at VCC =
3.3V, VBAT = 3.0V, and TA = +25°C, unless otherwise noted.) (Notes 2, 3)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSupply Voltage VCC2.33.35.5V
VBAT2.33.05.5V
Logic 1 Input SDA, SCLVIH0.7 x
VCC
VCC +
0.3V
Logic 0 Input SDA, SCLVIL-0.30.3 x
VCCV
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSActive Supply Current ICCA(Notes 4, 5)VCC = 3.63V200µAVCC = 5.5V300
Standby Supply CurrentICCS
I2C bus inactive, 32kHz
output on, SQW output off
(Note 5)
VCC = 3.63V110
VCC = 5.5V170
Temperature Conversion CurrentICCSCONVI2C bus inactive, 32kHz
output on, SQW output off
VCC = 3.63V575µAVCC = 5.5V650
Power-Fail VoltageVPF2.452.5752.70V
Logic 0 Output, 32kHz, INT/SQW,
SDAVOLIOL = 3mA0.4V
Logic 0 Output, RSTVOLIOL = 1mA0.4V
Output Leakage Current 32kHz,
INT/SQW, SDAILOOutput high impedance-10+1µA
Input Leakage SCLILI-1+1µA
RST Pin I/O LeakageIOLRST high impedance (Note 6)-200+10µA
VBAT Leakage Current
DS3231Extremely Accurate I2C-Integrated
RTC/TCXO/Crystal
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.
Absolute Maximum RatingsStresses 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.
Recommended Operating Conditions
Electrical Characteristics
(VCC = 0V, VBAT = 2.3V to 5.5V, TA = TMIN to TMAX, unless otherwise noted.) (Note 2)
(VCC = 2.3V to 5.5V, VCC = Active Supply (see Table 1), TA = TMIN to TMAX, unless otherwise noted.) (Typical values are at VCC =
3.3V, VBAT = 3.0V, and TA = +25°C, unless otherwise noted.) (Notes 2, 3)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSActive Battery Current IBATAEOSC = 0, BBSQW = 0,
SCL = 400kHz (Note 5)
VBAT = 3.63V70µAVBAT = 5.5V150
Timekeeping Battery Current IBATT
EOSC = 0, BBSQW = 0,
EN32kHz = 1,
SCL = SDA = 0V or
SCL = SDA = VBAT (Note 5)
VBAT = 3.63V0.843.0
VBAT = 5.5V1.03.5
Temperature Conversion CurrentIBATTC
EOSC = 0, BBSQW = 0,
SCL = SDA = 0V or
SCL = SDA = VBAT
VBAT = 3.63V575
VBAT = 5.5V650
Data-Retention CurrentIBATTDREOSC = 1, SCL = SDA = 0V, +25°C100nA
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSOutput FrequencyfOUTVCC = 3.3V or VBAT = 3.3V32.768kHz
Frequency Stability vs.
Temperature (Commercial)Δf/fOUT
VCC = 3.3V or
VBAT = 3.3V,
aging offset = 00h
0°C to +40°C±2
ppm
>40°C to +70°C±3.5
Frequency Stability vs.
Temperature (Industrial)Δf/fOUT
VCC = 3.3V or
VBAT = 3.3V,
aging offset = 00h
-40°C to <0°C±3.5
ppm0°C to +40°C±2
>40°C to +85°C±3.5
Frequency Stability vs. VoltageΔf/V1ppm/V
Trim Register Frequency
Sensitivity per LSBΔf/LSBSpeciied at:
-40°C0.7
ppm+25°C0.1
+70°C0.4
+85°C0.8
Temperature AccuracyTempVCC = 3.3V or VBAT = 3.3V-3+3°C
Crystal AgingΔf/fOAfter relow,
not production tested
First year±1.0ppm0–10 years±5.0
DS3231Extremely Accurate I2C-Integrated
RTC/TCXO/Crystal
Electrical Characteristics
Electrical Characteristics (continued)
(VCC = VCC(MIN) to VCC(MAX) or VBAT = VBAT(MIN) to VBAT(MAX), VBAT > VCC, TA = TMIN to TMAX, unless otherwise noted.) (Note 2)
(TA = TMIN to TMAX)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSCL Clock FrequencyfSCLFast mode100400kHzStandard mode0100
Bus Free Time Between STOP
and START ConditionstBUFFast mode1.3µsStandard mode4.7
Hold Time (Repeated) START
Condition (Note 7)tHD:STAFast mode0.6µsStandard mode4.0
Low Period of SCL ClocktLOWFast mode1.3µsStandard mode4.7
High Period of SCL ClocktHIGHFast mode0.6µsStandard mode4.0
Data Hold Time (Notes 8, 9)tHD:DATFast mode00.9µsStandard mode00.9
Data Setup Time (Note 10)tSU:DATFast mode100nsStandard mode250
START Setup TimetSU:STAFast mode0.6µsStandard mode4.7
Rise Time of Both SDA and SCL
Signals (Note 11)tRFast mode20 +
0.1CB
300nsStandard mode1000
Fall Time of Both SDA and SCL
Signals (Note 11)tFFast mode20 +
0.1CB
300nsStandard mode300
Setup Time for STOP ConditiontSU:STOFast mode0.6µsStandard mode4.7
Capacitive Load for Each Bus
Line CB(Note 11)400pF
Capacitance for SDA, SCLCI/O10pF
Pulse Width of Spikes That Must
Be Suppressed by the Input FiltertSP30ns
Pushbutton DebouncePBDB250ms
Reset Active TimetRST250ms
Oscillator Stop Flag (OSF) DelaytOSF(Note 12)100ms
Temperature Conversion TimetCONV125200ms
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSVCC Fall Time; VPF(MAX) to
VPF(MIN)tVCCF300µs
VCC Rise Time; VPF(MIN) to
VPF(MAX)tVCCR0µs
Recovery at Power-UptREC(Note 13)250300ms
DS3231Extremely Accurate I2C-Integrated
RTC/TCXO/Crystal
AC Electrical Characteristics
Power-Switch Characteristics
tRSTPBDB
RST
VCC
tVCCFtVCCR
tREC
VPF(MAX)
VPFVPF
VPF(MIN)
RST
DS3231Extremely Accurate I2C-Integrated
RTC/TCXO/Crystal
Pushbutton Reset Timing
Power-Switch Timing
WARNING: Negative undershoots below -0.3V while the part is in battery-backed mode may cause loss of data.
Note 2: Limits at -40°C are guaranteed by design and not production tested.
Note 3: All voltages are referenced to ground.
Note 4: ICCA—SCL clocking at max frequency = 400kHz.
Note 5: Current is the averaged input current, which includes the temperature conversion current.
Note 6: The RST pin has an internal 50kΩ (nominal) pullup resistor to VCC.
Note 7: After this period, the first clock pulse is generated.
Note 8: A device must internally provide a hold time of at least 300ns for the SDA signal (referred to the VIH(MIN) of the SCL sig-
nal) to bridge the undefined region of the falling edge of SCL.
Note 9: The maximum tHD:DAT needs only to be met if the device does not stretch the low period (tLOW) of the SCL signal.
Note 10: A fast-mode device can be used in a standard-mode system, but the requirement tSU:DAT ≥ 250ns must then be met. This
is automatically the case if the device does not stretch the low period of the SCL signal. If such a device does stretch the
low period of the SCL signal, it must output the next data bit to the SDA line tR(MAX) + tSU:DAT = 1000 + 250 = 1250ns
before the SCL line is released.
Note 11: CB—total capacitance of one bus line in pF.
Note 12: The parameter tOSF is the period of time the oscillator must be stopped for the OSF flag to be set over the voltage range of 0.0V ≤ VCC ≤ VCC(MAX) and 2.3V ≤ VBAT ≤ 3.4V.
Note 13: This delay applies only if the oscillator is enabled and running. If the EOSC bit is a 1, tREC is bypassed and RST immedi-
ately goes high. The state of RST does not affect the I2C interface, RTC, or TCXO.
SDA
SCL
tHD:STA
tLOW
tHIGHtF
tBUF
tHD:DAT
tSU:DATREPEATED
START
tSU:STA
tHD:STA
tSU:STO
tSP
STOPSTART
DS3231Extremely Accurate I2C-Integrated
RTC/TCXO/Crystal
Data Transfer on I2C Serial Bus
(VCC = +3.3V, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGEDS3231 toc02
VBAT (V)
IBAT
(µA)
VCC = 0V, BSY = 0,
SDA = SCL = VBAT OR VCC
EN32kHz = 1
EN32kHz = 0
SUPPLY CURRENT
vs. TEMPERATUREDS3231 toc03
TEMPERATURE (°C)
IBAT
(µA)3510-15
VCC = 0, EN32kHz = 1, BSY = 0,
SDA = SCL = VBAT OR GND
FREQUENCY DEVIATION
vs. TEMPERATURE vs. AGING VALUEDS3231 toc04
TEMPERATURE (°C)
FREQUENCY DEVIATION (ppm)3510-15
STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
DS3231 toc01
VCC (V)
CCS
(µA)
RST ACTIVE
BSY = 0, SCL = SDA = VCC
DELTA TIME AND FREQUENCY
vs. TEMPERATUREDELTA FREQUENCY (ppm)
DELTA TIME (MIN/YEAR)705060-10010203040-30-20
DS3231 toc05
CRYSTAL
+20ppm
CRYSTAL
-20ppm
TYPICAL CRYSTAL,
UNCOMPENSATED
DS3231
ACCURACY
BAND
DS3231Extremely Accurate I2C-Integrated
RTC/TCXO/Crystal
Typical Operating Characteristics
CLOCK AND CALENDAR
REGISTERS
USER BUFFER
(7 BYTES)
VOLTAGE REFERENCE;
DEBOUNCE CIRCUIT;
PUSHBUTTON RESET
I2C INTERFACE AND
ADDRESS REGISTER
DECODE
POWER CONTROL
VCC
VBAT
GND
SCL
SDA
TEMPERATURE
SENSOR
CONTROL LOGIC/
DIVIDER
ALARM, STATUS, AND
CONTROL REGISTERS
OSCILLATOR AND
CAPACITOR ARRAYX1
32kHz
INT/SQW
SQUARE-WAVE BUFFER;
INT/SQW CONTROL
RST
VCC
DS32311Hz
1Hz
DS3231Extremely Accurate I2C-Integrated
RTC/TCXO/Crystal
Block Diagram
Detailed DescriptionThe DS3231 is a serial RTC driven by a temperature-
compensated 32kHz crystal oscillator. The TCXO provides
a stable and accurate reference clock, and maintains the
RTC to within ±2 minutes per year accuracy from -40°C
to +85°C. The TCXO frequency output is available at the
32kHz pin. The RTC is a low-power clock/calendar with
two programmable time-of-day alarms and a programma-
ble square-wave output. The INT/SQW provides either an
interrupt signal due to alarm conditions or a square-wave
output. 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 the 24-hour or 12-hour
format with an AM/PM indicator. The internal registers are
accessible though an I2C bus interface.
A temperature-compensated voltage reference and com-
parator circuit monitors the level of VCC to detect power fail-
ures and to automatically switch to the backup supply when
necessary. The RST pin provides an external pushbutton
function and acts as an indicator of a power-fail event.
OperationThe block diagram shows the main elements of the
DS3231. The eight blocks can be grouped into four func-
tional groups: TCXO, power control, pushbutton function,
and RTC. Their operations are described separately in the
PINNAMEFUNCTION32kHz32kHz Output. This open-drain pin requires an external pullup resistor. When enabled, the output operates on
either power supply. It may be left open if not used.VCCDC Power Pin for Primary Power Supply. This pin should be decoupled using a 0.1µF to 1.0µF capacitor.
If not used, connect to ground.INT/SQW
Active-Low Interrupt or Square-Wave Output. This open-drain pin requires an external pullup resistor connected
to a supply at 5.5V or less. This multifunction pin is determined by the state of the INTCN bit in the Control
Register (0Eh). When INTCN is set to logic 0, this pin outputs a square wave and its frequency is determined by
RS2 and RS1 bits. When INTCN is set to logic 1, then a match between the timekeeping registers and either of
the alarm registers activates the INT/SQW pin (if the alarm is enabled). Because the INTCN bit is set to logic 1 when power is irst applied, the pin defaults to an interrupt output with alarms disabled. The pullup voltage can
be up to 5.5V, regardless of the voltage on VCC. If not used, this pin can be left unconnected.RST
Active-Low Reset. This pin is an open-drain input/output. It indicates the status of VCC relative to the
VPF speciication. As VCC falls below VPF, the RST pin is driven low. When VCC exceeds VPF, for tRST, the
RST pin is pulled high by the internal pullup resistor. The active-low, open-drain output is combined with a
debounced pushbutton input function. This pin can be activated by a pushbutton reset request. It has an internal 50kΩ nominal value pullup resistor to VCC. No external pullup resistors should be connected. If the oscillator is
disabled, tREC is bypassed and RST immediately goes high.
5–12N.C.No Connection. Must be connected to ground.GNDGroundVBAT
Backup Power-Supply Input. When using the device with the VBAT input as the primary power source, this pin
should be decoupled using a 0.1µF to 1.0µF low-leakage capacitor. When using the device with the VBAT input
as the backup power source, the capacitor is not required. If VBAT is not used, connect to ground. The device is
UL recognized to ensure against reverse charging when used with a primary lithium battery.
Go to www.maximintegrated.com/qa/info/ul. SDASerial Data Input/Output. This pin is the data input/output for the I2C serial interface. This open-drain pin
requires an external pullup resistor. The pullup voltage can be up to 5.5V, regardless of the voltage on VCC.SCLSerial Clock Input. This pin is the clock input for the I2C serial interface and is used to synchronize data
movement on the serial interface. Up to 5.5V can be used for this pin, regardless of the voltage on VCC.
DS3231Extremely Accurate I2C-Integrated
RTC/TCXO/Crystal
Pin Description
32kHz TCXOThe 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 capacitance selection reg-
isters. 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 VCC and once every 64 seconds afterwards.
Power ControlThis function is provided by a temperature-compensated
voltage reference and a comparator circuit that monitors
the VCC level. When VCC is greater than VPF, the part is
powered by VCC. When VCC is less than VPF but greater
than VBAT, the DS3231 is powered by VCC. If VCC is less
than VPF and is less than VBAT, the device is powered by
VBAT. See Table 1.
To preserve the battery, the first time VBAT is applied
to the device, the oscillator will not start up until VCC
exceeds VPF, or until a valid I2C address is written to
the part. Typical oscillator startup time is less than one
second. Approximately 2 seconds after VCC is applied,
or a valid I2C address is written, the device makes a
temperature measurement and applies the calculated
correction to the oscillator. Once the oscillator is running,
it continues to run as long as a valid power source is avail-
able (VCC or VBAT), and the device continues to measure
the temperature and correct the oscillator frequency every
64 seconds.
On the first application of power (VCC) or when a valid I2C
address is written to the part (VBAT), the time and date
registers are reset to 01/01/00 01 00:00:00 (DD/MM/YY
DOW HH:MM:SS).
VBAT OperationThere are several modes of operation that affect the
amount of VBAT current that is drawn. While the device
is powered by VBAT and the serial interface is active,
active battery current, IBATA, is drawn. When the seri-
al interface is inactive, timekeeping current (IBATT),
which includes the averaged temperature conversion
current, IBATTC, is used (refer to Application Note 3644:
Power Considerations for Accurate Real-Time Clocks
for details). Temperature conversion current, IBATTC, is
specified since the system must be able to support the
periodic higher current pulse and still maintain a valid volt-
age level. Data retention current, IBATTDR, is the current
drawn by the part when the oscillator is stopped (EOSC
= 1). This mode can be used to minimize battery require-
ments for times when maintaining time and date informa-
tion is not necessary, e.g., while the end system is waiting
to be shipped to a customer.
Pushbutton Reset FunctionThe DS3231 provides for a pushbutton switch to be con-
nected 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 (PBDB), the DS3231
continues to monitor the RST line. 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 tRST.
RST is also used to indicate a power-fail condition. When
VCC is lower than VPF, an internal power-fail signal is
generated, which forces the RST pin low. When VCC
returns to a level above VPF, the RST pin is held low for
approximately 250ms (tREC) to allow the power supply
to stabilize. If the oscillator is not running (see the Power
Control section) when VCC is applied, tREC is 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.
Real-Time ClockWith 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 automati-
cally adjusted for months with fewer than 31 days, includ-
ing 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 con-
trolled by the bit INTCN.
Table 1. Power Control
SUPPLY CONDITIONACTIVE SUPPLYVCC < VPF, VCC < VBATVBAT
VCC < VPF, VCC > VBATVCC
VCC > VPF, VCC < VBATVCC
VCC > VPF, VCC > VBATVCC
DS3231Extremely Accurate I2C-Integrated
RTC/TCXO/Crystal
