DS3232 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
MFG CO.
'DS3232' PDF : 18 Pages View PDF
Extremely Accurate I2C RTC with
Integrated Crystal and SRAM
Pin Description
PIN
NAME
FUNCTION
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.
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
5
INT/SQW
(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.
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
6
RST 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
Backup Power-Supply Input. This pin should be decoupled using a 0.1μF to 1.0μF low-leakage capacitor.
If the I2C interface is inactive whenever the device is powered by the VBAT input, the decoupling capacitor
16
VBAT is not required. If VBAT is not used, connect to ground. Diodes placed in series between the VBAT pin and
the battery can cause improper operation. UL recognized to ensure against reverse charging when used
with a lithium battery. Go to www.maxim-ic.com/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.
18, 20
Serial-Clock Input. This pin is the clock input for the I2C serial interface and is used to synchronize data
SCL 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 floating.
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 VCC to detect
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. Also available are 236 bytes of
general-purpose battery-backed SRAM.
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