±5ppm, I2C Real-Time Clock
TOP VIEW
32KHZ 1
VCC 2
INT/SQW 3
RST 4
N.C. 5
N.C. 6
N.C. 7
N.C. 8
+
DS3231M
SO
16 SCL
15 SDA
14 VBAT
13 GND
12 N.C.
11 N.C.
10 N.C.
9 N.C.
Pin Configuration
TOP VIEW
+
32KHZ 1
VCC 2
INT/SQW 3
DS3231M
RST 4
SO
8 SCL
7 SDA
6 VBAT
5 GND
Pin Description
PIN
8 SO 16 SO
1
1
2
2
3
3
4
4
—
5–12
5
13
6
14
NAME
32KHZ
VCC
INT/
SQW
RST
N.C.
GND
VBAT
FUNCTION
32.768kHz Output (50% Duty Cycle). This open-drain pin requires an external pullup resistor.
When enabled with the EN32KHZ bit in the Status register (0Fh), this output operates on either
power supply. This pin can be left open circuit if not used.
DC Power Pin for Primary Power Supply. This pin should be decoupled using a 0.1FF to 1.0FF
capacitor. Connect to ground if not used.
Active-Low Interrupt or 1Hz Square-Wave Output. This open-drain pin requires an external pullup
resistor connected to a supply at 5.5V or less. 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 1Hz square wave. When INTCN is set to logic 1, 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 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 50kI (RPU) 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.
No Connection. These pins must be connected to ground.
Ground
Backup Power-Supply Input. When using the device with the VBAT input as the primary power
source, this pin should be decoupled using a 0.1FF to 1.0FF 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.maxim-ic.com/qa/info/ul for more information.
7