DS3231S+ DALLAS [Dallas Semiconductor], DS3231S+ Datasheet - Page 9

• Manufacturer Part Number: DS3231S+
• Description: Extremely Accurate I2C-Integrated RTC/TXO/Crystal
• Manufacturer: DALLAS [Dallas Semiconductor]

The DS3231 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,
5–12
PIN
13
14
15
16
1
2
3
4
INT/SQW
NAME
32kHz
GND
V
N.C.
SDA
SCL
V
RST
BAT
CC
32kHz Output. This open-drain pin requires an external pullup resistor. It may be left open if not used.
DC 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.
Active-Low Interrupt or Square-Wave Output. This open-drain pin requires an external pullup resistor. It may 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.
Acti ve- Low Reset. Thi s p i n i s an op en- d r ai n i np ut/outp ut. It i nd i cates the status of V
V
p i n i s d r i ven hi g h i m p ed ance. The acti ve- l ow , op en- d r ai n outp ut i s com b i ned w i th a d eb ounced p ushb utton
i np ut functi on. Thi s p i n can b e acti vated b y a p ushb utton r eset r eq uest. It has an i nter nal 50kΩ nom i nal val ue
p ul l up r esi stor to V
star tup ti m e of the osci l l ator i s ad d ed to the t
No Connection. Must be connected to ground.
Ground
Backup Power-Supply Input. This pin should be decoupled using a 0.1µF to 1.0µF low-leakage capacitor.
If the I
not required. If V
used with a lithium battery. Go to www.maxim-ic.com/qa/info/ul.
Serial Data Input/Output. This pin is the data input/output for the I
requires an external pullup resistor.
Serial Clock Input. This pin is the clock input for the I
movement on the serial interface.
P F
Detailed Description
sp eci fi cati on. As V
2
C interface is inactive whenever the device is powered by the V
Extremely Accurate I
B A T
C C
. N o exter nal p ul l up r esi stor s shoul d b e connected . If the cr ystal osci l l ator i s d i sab l ed , the
is not used, connect to ground. UL recognized to ensure against reverse charging when
_____________________________________________________________________
C C
fal l s b el ow V
P F
, the RS T p i n i s d r i ven l ow . W hen V
R S T
d el ay.
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 I
A temperature-compensated voltage reference and
comparator circuit monitors the level of V
power failures and to automatically switch to the back-
up supply when necessary. The RST pin provides an
external pushbutton function and acts as an indicator
of a power-fail event.
FUNCTION
2
C serial interface and is used to synchronize data
RTC/TCXO/Crystal
2
C serial interface. This open-drain pin
B A T
2
2
C C
input, the decoupling capacitor is
C bus interface.
C-Integrated
exceed s V
C C
Pin Description
r el ati ve to the
P F
, for t
R S T
CC
, the RS T
to detect
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