DS3232-DS3232SN#T&R Fast Delivery |IC PHOENIX CO.,LIMITED

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DS3232-DS3232SN#T&R
Extremely Accurate I²C RTC with Integrated Crystal and SRAM
AVAILABLE
EVALUATION KIT AVAILABLE
General Description
The DS3232 is a low-cost temperature-compensated
crystal oscillator (TCXO) with a very accurate, tempera-
ture-compensated, integrated real-time clock (RTC) and
236 bytes of battery-backed SRAM. Additionally, the
DS3232 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 DS3232
is available in commercial and industrial temperature
ranges, and is offered in an industry-standard 20-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 RSTpin is monitored as a
pushbutton input for generating a µP reset.
Applications
ServersUtility Power Meters
TelematicsGPS
FeaturesAccuracy ±2ppm from 0°C to +40°CAccuracy ±3.5ppm from -40°C to +85°CBattery Backup Input for ContinuousTimekeepingOperating Temperature RangesCommercial: 0°C to +70°CIndustrial: -40°C to +85°C236 Bytes of Battery-Backed SRAMLow-Power ConsumptionReal-Time Clock Counts Seconds, Minutes,Hours, Day, Date, Month, and Year with Leap YearCompensation Valid Up to 2099Two Time-of-Day AlarmsProgrammable Square-Wave OutputFast (400kHz) I2C Interface3.3V OperationDigital Temp Sensor Output: ±3°C AccuracyRegister for Aging TrimRSTInput/Output300-Mil, 20-Pin SO PackageUnderwriters Laboratories Recognized
Extremely Accurate I2C RTC with
Integrated Crystal and SRAM
Ordering Information
PART TEMP RANGE PIN-
PACKAGE
TOP
MARK
DS3232S# 0°C to +70°C 20 SO DS3232
DS3232SN# -40°C to +85°C 20 SO DS3232N
DS3232
VCC
SCL
RPU
RPU = tR / CB
RPU
INT/SQW
32kHz
VBAT
PUSH-
BUTTON
RESET
SDA
RST
N.C.
N.C.
N.C.
N.C.
VCC
VCC
GND
VCC
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
SCL
RST
SDA
Typical Operating Circuit
#Denotes a RoHS-compliant device that may include lead that
is exempt under the RoHS requirements. Lead finish is JESD97
Category e3, and is compatible with both lead-based and
lead-free soldering processes. A "#" anywhere on the top mark
denotes a RoHS-compliant device.
Pin Configuration
DS3232
TOP VIEW
SCL
N.C.
SCL
SDAVCC
32kHz
N.C.
N.C.
VBAT
GND
N.C.
N.C.N.C.
N.C.
RST
INT/SQW
N.C.
N.C.N.C.
N.C.
DS3232
Extremely Accurate I2C RTC with
Integrated Crystal and SRAM
ABSOLUTE MAXIMUM RATINGS
RECOMMENDED OPERATING CONDITIONS
(TA= -40°C to +85°C, unless otherwise noted.) (Notes 2, 3)
Stresses 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.
Voltage Range on VCC, VBAT, 32kHz, SCL, SDA, RST,
INT/SQW Relative to Ground.............................-0.3V to +6.0V
Junction-to-Ambient Thermal Resistance (θJC) (Note 1)..55.1°C/W
Junction-to-Case Thermal Resistance (θJC) (Note 1)..........24°C/W
Operating Temperature Range
(noncondensing).............................................-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, PC Board Layout, and Assemblysection.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
VCC 2.3 3.3 5.5 Supply Voltage VBAT 2.3 3.0 5.5 V
Logic 1 Input SDA, SCL VIH0.7 x
VCC
VCC +
0.3 V
Logic 0 Input SDA, SCL VIL -0.3 +0.3 x
VCCV
ELECTRICAL CHARACTERISTICS
(VCC= 2.3V to 5.5V, VCC= active supply (see Table 1), TA= -40°C to +85°C, unless otherwise noted.) (Typical values are at VCC=
3.3V, VBAT= 3.0V, and TA= +25°C, unless otherwise noted.) (Notes 2, 3)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
VCC = 3.3V200Active Supply CurrentICCA32kHz output off
(Notes 4, 5)VCC = 5.5V325µA
VCC = 3.3V120
Standby Supply CurrentICCS
I2C bus inactive, 32kHz
output off, SQW output off
(Note 5)VCC = 5.5V160
VCC = 3.3V500Temperature Conversion CurrentICCSCONVI2C bus inactive, 32kHz
output off, SQW output offVCC = 5.5V600µA
Power-Fail VoltageVPF2.452.5752.70V
ACTIVE SUPPLY (Table 1 ) (2.3V to 5.5V, TA = -40°C to +85°C, unless otherwise noted) (Note 2)
Logic 1 Output, 32kHz
IOH = -1mA
IOH = -0.75mA
IOH = -0.14mA
VOH
Active supply > 3.3V,
3.3V > active supply > 2.7V,
2.7V > active supply > 2.3V
2.0V
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 /thermal-tutorial.
DS3232
Extremely Accurate I2C RTC with
Integrated Crystal and SRAM
ELECTRICAL CHARACTERISTICS (continued)
(VCC= 2.3V to 5.5V, VCC= active supply (see Table 1), TA= -40°C to +85°C, unless otherwise noted.) (Typical values are at VCC=
3.3V, VBAT= 3.0V, and TA= +25°C, unless otherwise noted.) (Notes 2, 3)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSLogic 0 Output, INT/SQW, SDA VOL IOL = 3mA 0.4 VLogic 0 Output, RST, 32kHz VOL IOL = 1mA 0.4 VOutput Leakage Current 32kHz,
INT/SQW, SDA ILO Output high impedance -1 0 +1µAInput Leakage SCL ILI -1 +1µARST Pin I/O Leakage IOL RST high impedance (Note 6) -200 +10 µATCXO Output Frequency fOUT VCC = 3.3V or VBAT = 3.3V 32.768 kHzDuty Cycle
(Revision A3 Devices) 2.97V ≤ VCC < 3.63 31 69 %0°C to +40°C -2 +2 Frequency Stability vs.
Temperature Δf/fOUT VCC = 3.3V or
VBAT = 3.3V - 40° C to 0°C and 40° C to + 85°C -3.5 +3.5 ppmFrequency Stability vs. Voltage Δf/V VCC = 3.3V or VBAT = 3.3V 1 ppm/V-40°C 0.7 +25°C 0.1 +70°C 0.4 Trim Register Frequency
Sensitivity per LSB Δf/LSB Specified at:+85°C 0.8 ppm
Temperature AccuracyTempVCC = 3.3V or VBAT = 3.3V-3+3°C
First year±1.0Crystal AgingΔf/f0After reflow,
not production tested0–10 years±5.0ppm
ELECTRICAL CHARACTERISTICS
(VCC= 0V, VBAT= 2.3V to 5.5V, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
VBAT = 3.3V80Active Battery Current
(Note 5)IBATAEO SC = 0, BBS Q W = 0,C L = 400kH z, BB32kH z = 0VBAT = 5.5V200µA
VBAT = 3.4V1.52.5Timekeeping Battery Current
(Note 5)IBATT
EOSC = 0, BBSQW = 0,
SCL = SDA = 0V,
BB32kHz = 0,
CRATE0 = CRATE1 = 0VBAT = 5.5V1.53.0
Temperature Conversion CurrentIBATTCEOSC = 0, BBSQW = 0, SCL = SDA = 0V600µA
Data-Retention CurrentIBATTDREOSC = 1, SCL = SDA = 0V, +25°C100nA
DS3232
Extremely Accurate I2C RTC with
Integrated Crystal and SRAM
AC ELECTRICAL CHARACTERISTICS
(Active supply (see Table 1) = 2.3V to 5.5V, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
Fast mode100400SCL Clock FrequencyfSCLStandard mode0.04100kHz
Fast mode1.3Bus Free Time Between STOP
and START ConditionstBUFStandard mode4.7µs
Fast mode0.6Hold Time (Repeated) START
Condition (Note 7)tHD:STAStandard mode4.0µs
Fast mode1.325,000Low Period of SCL ClocktLOWStandard mode4.725,000µs
Fast mode0.6High Period of SCL ClocktHIGHStandard mode4.0µs
Fast mode00.9Data Hold Time (Notes 8, 9)tHD:DATStandard mode00.9µs
Fast mode100Data Setup Time (Note 10)tSU:DATStandard mode250ns
Fast mode0.6Start Setup TimetSU:STAStandard mode4.7µs
Fast mode300Rise Time of Both SDA and SCL
Signals (Note 11)tRStandard mode
20 +
0.1CB1000ns
Fast mode300Fall Time of Both SDA and SCL
Signals (Note 11)tFStandard mode
20 +
0.1CB300ns
Fast mode0.6Setup Time for STOP ConditiontSU:STOStandard mode4.7µs
Capacitive Load for Each Bus
Line (Note 11)CB400pF
Capacitance for SDA, SCLCI/O10pF
Pulse Width of Spikes That Must
Be Suppressed by the Input FiltertSP30ns
Pushbutton DebouncePBDB250ms
Interface TimeouttIF(Note 12)2535ms
Reset Active TimetRST250ms
Oscillator Stop Flag (OSF) DelaytOSF(Note 13)100ms
Temperature Conversion TimetCONV125200ms
POWER-SWITCH CHARACTERISTICS
(TA= -40°C to +85°C)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
VCC Fall Time; VPF(MAX) to
VPF(MIN)tVCCF300µs
VCC Rise Time; VPF(MIN) to
VPF(MAX)tVCCR0µs
DS3232
Extremely Accurate I2C RTC with
Integrated Crystal and SRAM
Pushbutton Reset Timing
tRSTPBDB
RST
Power-Switch Timing
VCCPF(MAX)
RST
VPF(MIN)
tVCCFtVCCR
tREC
VPFVPF
DS3232
Extremely Accurate I2C RTC with
Integrated Crystal and SRAM
Data Transfer on I2C Serial Bus
SCL
NOTE: TIMING IS REFERENCED TO VIL(MAX) AND VIH(MIN).
SDA
STOPSTARTREPEATED
START
tBUF
tHD:STA
tHD:DATtSU:DAT
tSU:STO
tHD:STAtSP
tSU:STAtHIGH
tLOW
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 RSTpin 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 signal)
to bridge the undefined region of the falling edge of SCL.
Note 9:The maximum tHD:DATneeds 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:Minimum operating frequency of the I2C interface is imposed by the timeout period.
Note 13:The parameter tOSFis the period of time the oscillator must be stopped for the OSF flag to be set over the voltage range of
0V ≤VCC≤VCC(MAX) and 2.3V ≤VBAT≤3.4V.
Note 14:This delay only applies if the oscillator is enabled and running. If the EOSCbit is 1, tRECis bypassed and RSTimmediately
goes high.
WARNING: Negative undershoots below -0.3V while the part is in battery-backed mode may
cause loss of data.
DS3232
Extremely Accurate I2C RTC with
Integrated Crystal and SRAM
STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
DS3232 toc01
VCC (V)
SUPPLY CURRENT (nA)
RST ACTIVE
SCL = SDA = VCC
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
DS3232 toc02
VBAT (V)
SUPPLY CURRENT (nA)
VCC = 0V
BB32kHz = 0
BBSQW = 0
BSY = 0
SUPPLY CURRENT
vs. TEMPERATURE
DS3232 toc03
TEMPERATURE (°C)
SUPPLY CURRENT (6040-20020
VCC = 0V
BB32kHz = 0
VBAT = 3.4V
VBAT = 3.0V
FREQUENCY DEVIATION
vs. TEMPERATURE vs. AGING
DS3232 toc04
TEMPERATURE (°C)
FREQUENCY DEVIATION (ppm)6040-20020
AGING = -128
AGING = -33
AGING = +127
AGING = 0
AGING = +32
Typical Operating Characteristics
(VCC= +3.3V, TA = +25°C, unless otherwise noted.)
DELTA TIME AND FREQUENCY
vs. TEMPERATURE
TEMPERATURE (°C)
DELTA FREQUENCY (ppm)
DELTA TIME (MIN/YEAR)705060-10010203040-30-20
DS3232 toc05
CRYSTAL
+20ppm
CRYSTAL
-20ppm
TYPICAL CRYSTAL,
UNCOMPENSATED
DS3232
ACCURACY
BAND
DS3232
Extremely Accurate I2C RTC with
Integrated Crystal and SRAM
Block Diagram
RST
VCC
INT/SQW
CLOCK AND CALENDAR
REGISTERS
SRAM
USER BUFFER
(7 BYTES)
I2C INTERFACE AND
ADDRESS REGISTER
DECODE
POWER CONTROL
VCC
VBAT
GND
SCL
SDA
TEMPERATURE
SENSOR
CONTROL LOGIC/
DIVIDER
SQUARE-WAVE BUFFER;
INT/SQW CONTROL
CONTROL AND STATUS
REGISTERS
VOLTAGE REFERENCE;
DEBOUNCE CIRCUIT;
PUSHBUTTON RESET
OSCILLATOR AND
CAPACITOR ARRAY
DS3232
32kHz
Detailed Description
The DS3232 is a serial RTC driven by a temperature-
compensated 32kHz crystal oscillator. The TCXO pro-
vides a stable and accurate reference clock, and
maintains the RTC to within ±2 minutes per year accu-
racy 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 programmable square-wave output. The
INT/SQW provides either an interrupt signal due to
alarm conditions or a square-wave output. The clock/cal-
endar 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
comparator circuit monitors the level of VCCto detect
DS3232
Extremely Accurate I2C RTC with
Integrated Crystal and SRAM
Pin Description
PINNAMEFUNCTION
1, 2,
7–14, 19 N.C. No Connection. Not connected internally. Must be connected to ground.
3 32kHz 32kHz Push-Pull Output. If disabled with either EN32kHz = 0 or BB32kHz = 0, the state of the 32kHz pin
will be low.
4 VCC DC Power Pin for Primary Power Supply. This pin should be decoupled using a 0.1μF to 1.0μF capacitor. INT/SQW
Active-Low Interrupt or Square-Wave Output. This open-drain pin requires an external pullup resistor. It can
be left open if not used. 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 first 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 specification. As VCC falls below VPF, the RST pin is driven low. When VCC exceeds VPF, for tRST, the
RST pin is driven high impedance. 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 50k
nominal value pullup resistor to VCC. No external pullup resistors should be connected. If the crystal
oscillator is disabled, tRST is bypassed and RST immediately goes high.
15 GND Ground
16 VBAT
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 /qa/info/ul.
17 SDA Serial-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.
18, 20 SCL
Serial-Clock Input. This pin is the clock input for the I2C serial interface and is used to synchronize data
movement on the serial interface. A connection to only one of the pins is required. The other pin must be
connected to the same signal or be left unconnected. Up to 5.5V can be used for this pin, regardless of the
voltage on VCC.
power failures and to automatically switch to the back-
up supply when necessary. The RSTpin provides an
external pushbutton function and acts as an indicator of
a power-fail event. Also available are 236 bytes of gen-
eral-purpose battery-backed SRAM.
Operation
The block diagram shows the main elements of the
DS3232. The eight blocks can be grouped into four
functional groups: TCXO, power control, pushbutton
function, and RTC. Their operations are described sep-
arately in the following sections.
32kHz TCXO
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. The tempera-
ture is read on initial application of VCCand once every
64 seconds (default, see the description for CRATE1
and CRATE0 in the control/status register) afterwards.
DS3232
Power Control
This function is provided by a temperature-compensat-
ed voltage reference and a comparator circuit that
monitors the VCClevel. When VCCis greater than VPF,
the part is powered by VCC. When VCCis less than VPF
but greater than VBAT, the DS3232 is powered by VCC.
If VCCis less than VPFand is less than VBAT, the
device is powered by VBAT. See Table 1.
To preserve the battery, the first time VBATis applied to
the device, the oscillator does not start up and no tem-
perature conversions take place until VCCexceeds VPF
or until a valid I2C address is written to the part. After
the first time VCCis ramped up, the oscillator starts up
and the VBATsource powers the oscillator during
power-down and keeps the oscillator running. When
the DS3232 switches to VBAT, the oscillator may be dis-
abled by setting the EOSCbit.
VBATOperation
There are several modes of operation that affect the
amount of VBATcurrent that is drawn. While the device
is powered by VBATand the serial interface is active,
active battery current, IBATA, is drawn. When the serial
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 Clocksfor
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
voltage 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 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.
Pushbutton Reset Function
The DS3232 provides for a pushbutton switch to be con-
nected to the RSToutput pin. When the DS3232 is not in
a reset cycle, it continuously monitors the RSTsignal for a
low going edge. If an edge transition is detected, the
DS3232 debounces the switch by pulling the RSTlow.
After the internal timer has expired (PBDB), the DS3232
continues to monitor the RSTline. If the line is still low, the
DS3232 continuously monitors the line looking for a rising
edge. Upon detecting release, the DS3232 forces the
RSTpin low and holds it low for tRST.
The same pin, RST, is used to indicate a power-fail con-
dition. When VCCis lower than VPF, an internal power-
fail signal is generated, which forces the RSTpin low.
When VCCreturns to a level above VPF, the RSTpin is
held low for tRECto allow the power supply to stabilize.
If the oscillator is not running (see the Power Control
section) when VCCis applied, tRECis bypassed and
RSTimmediately goes high.
Assertion of the RSToutput, whether by pushbutton or
power-fail detection, does not affect the internal opera-
tion of the DS3232.
Real-Time Clock
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 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 controlled by the bit INTCN.
SRAM
The DS3232 provides 236 bytes of general-purpose
battery-backed read/write memory. The I2C address
ranges from 14h to 0FFh. The SRAM can be written or
read whenever VCCor VBATis greater than the mini-
mum operating voltage.
Address Map
Figure 1 shows the address map for the DS3232 time-
keeping registers. During a multibyte access, when the
address pointer reaches the end of the register space
(0FFh), it wraps around to location 00h. On an I2C
START or address pointer incrementing to location 00h,
the current time is transferred to a second set of regis-
ters. The time information is read from these secondary
registers, while the clock may continue to run. This
eliminates the need to reread the registers in case the
main registers update during a read.2C Interface
The I2C interface is accessible whenever either VCCor
VBATis at a valid level. If a microcontroller connected to
the DS3232 resets because of a loss of VCCor other
Extremely Accurate I2C RTC with
Integrated Crystal and SRAM
SUPPLY CONDITIONPOWERED BY
VCC < VPF, VCC < VBATVBAT
VCC < VPF, VCC > VBATVCC
VCC > VPF, VCC < VBATVCC
VCC > VPF, VCC > VBATVCC
Table 1. Power Control
DS3232

Partno	Mfg	Dc	Qty	Available	Descript
DS3232	MAXIM	N/a	8	avai	Extremely Accurate I²C RTC with Integrated Crystal and SRAM
DS3232SN#T&R \|DS3232SNT&R	DALLAS	N/a	2000	avai	Extremely Accurate I²C RTC with Integrated Crystal and SRAM