DS3231 real-time clock pinout

The DS3231 is a battery-backed I²C real-time clock with a temperature-compensated crystal oscillator, two alarms, and a programmable square-wave output.

SO-16 · 300 mil

16 contacts Current package

Analog Devices / Maxim Integrated ·

−40 to +85 °C.

SO-16 · 300 mil pinout

Top view. Start at the package pin-1 index and follow the numbered leads.

Selected pin details

15 · SDA

Bidirectional · Bidirectional

Open-drain I²C data. The bus needs a pull-up to its logic rail.

Analog Devices / Maxim DS3231 datasheet, electrical characteristics, pin description, and typical operating circuit.

Electrical limits · Link to this pin

All 16 pins

Pin	Signal	Direction	Function
1	32kHz Open-drain output	Open-drain output	32.768 kHz output. Use an external pull-up when enabled and connected.
2	VCC Supply input	Supply input	Primary device supply. Place the bypass capacitor close to this pin.
3	INT/SQW Open drain	Open drain	Alarm interrupt or programmable square wave. Add a pull-up when used.
4	RST Bidirectional	Bidirectional	Active-low reset status and debounced pushbutton input, with internal pull-up.
5	NC Tie to ground	Tie to ground	No internal signal connection. The manufacturer requires a ground connection.
6	NC Tie to ground	Tie to ground	No internal signal connection. The manufacturer requires a ground connection.
7	NC Tie to ground	Tie to ground	No internal signal connection. The manufacturer requires a ground connection.
8	NC Tie to ground	Tie to ground	No internal signal connection. The manufacturer requires a ground connection.
9	NC Tie to ground	Tie to ground	No internal signal connection. The manufacturer requires a ground connection.
10	NC Tie to ground	Tie to ground	No internal signal connection. The manufacturer requires a ground connection.
11	NC Tie to ground	Tie to ground	No internal signal connection. The manufacturer requires a ground connection.
12	NC Tie to ground	Tie to ground	No internal signal connection. The manufacturer requires a ground connection.
13	GND Supply return	Supply return	Connect to the common ground plane or bench return.
14	VBAT Supply input	Supply input	Backup supply input. Ground it when no backup source is used.
15	SDA Bidirectional	Bidirectional	Open-drain I²C data. The bus needs a pull-up to its logic rail.
16	SCL Input	Input	I²C clock. Connect to the host clock line with its bus pull-up.

Signal assignments

I²C

7-bit address 0x68, up to 400 kHz. Use consecutive reads to retrieve the buffered calendar fields.

Alarm / square wave

Use a pull-up and program INTCN in the control register to select alarms or square wave.

INT/SQW (3)

Electrical limits

Parameter	Limit	Conditions and source
Main supply2.3–5.5 V	2.3–5.5 V	Verify main power versus the power-fail threshold when using a backup cell. Analog Devices / Maxim DS3231 datasheet, electrical characteristics, pin description, and typical operating circuit.
Backup supply2.3–5.5 V	2.3–5.5 V	A 3 V primary lithium cell is suitable for the bare IC. Analog Devices / Maxim DS3231 datasheet, electrical characteristics, pin description, and typical operating circuit.
Oscillator accuracy±2 ppm	±2 ppm	0 to +40 °C. Consult the part grade and temperature conditions for wider ranges. Analog Devices / Maxim DS3231 datasheet, electrical characteristics, pin description, and typical operating circuit.
I²C speed400 kHz maximum	400 kHz maximum	Size the pull-ups for bus capacitance and logic thresholds. Analog Devices / Maxim DS3231 datasheet, electrical characteristics, pin description, and typical operating circuit.

Models and documents

This map covers the quartz-based DS3231 in a 16-lead wide SO package. Verify the separate DS3231M MEMS datasheet for an M suffix.

DS3231S#: 0 to +70 °C.
DS3231SN#: −40 to +85 °C.

DS3231 manufacturer documentation· Analog Devices / Maxim DS3231 datasheet, electrical characteristics, pin description, and typical operating circuit.