# RTC Module DS1307, I2C Interface, 5V

> RTC module based on the DS1307 chip, with I2C interface (address 0x68) and 5V power supply. Provides seconds, minutes, hours, day of week, date, month and year, with automatic leap year correction up to 2100. Supports 24h/12h format with AM/PM, includes 56 bytes of non-volatile RAM and backup via a CR1220 battery (not included). 32.768 kHz crystal, accuracy ~1s/day, operating temperature -40~85°C, dimensions 41x23 mm.

- Page: https://sigmanortec.ro/en/rtc-module-ds1307-i2c-interface-5v
- Price: 13.12 RON
- Availability: In stock; 1-2 zile
- Reference: 88175 · EAN: 5949843371920
- Category: Mechatronics and IoT > Sensors and Modules > Clock Module
- Specifications: Main IC: DS1307; Supply voltage: 5 V; Communication interface: I2C
- Updated: 2026-09-14
- Shop: [Sigmanortec.ro](https://sigmanortec.ro/en/llms.txt)
- Prices: RON, VAT included; prices and stock as of 2026-10-22 01:33 (Europe/Bucharest)

## Description

Real-time clock for embedded projects, maintains date and time even without power through backup on CR1220 battery. Communicates simply via I2C at 0x68 using only SDA and SCL, offers full time with automatic correction for months and leap years up to 2100, supports 24h or 12h format with AM PM, and includes 56 bytes of non-volatile RAM for settings.
The RTC DS1307 module is a precision real-time clock based on the DS1307 integrated circuit, designed for applications that require accurate tracking of date and time in embedded systems. It provides complete time information: seconds, minutes, hours, day of the week, date, month, and year, with automatic compensation for months with less than 31 days and for leap years up to 2100, eliminating the need for manual corrections in the firmware.
The module supports both 24-hour format and 12-hour format with AM/PM indicator, and includes 56 bytes of non-volatile RAM, useful for storing configuration or logging data. Communication with the microcontroller is done via the I2C interface at the fixed address 0x68, using only two pins (SDA and SCL), making it compatible with 5V boards such as Arduino Uno, Arduino Mega, as well as STM32, ESP32, and any other platform that supports the I2C protocol, as long as a logic level converter to 3.3V. is used.
An integrated voltage drop detection circuit automatically switches to the CR1220 backup battery not included (2.0-3.5V) when the main 5V power supply is interrupted, maintaining the correct time over extended periods without external power. The 32.768 kHz quartz crystal ensures an accuracy of approximately 1 second per day, and the operating temperature range between -40 and 85°C allows use in demanding industrial environments.
Specifications:
Operating voltage: 5 VDC
Backup battery voltage: 2.0 - 3.5V (CR1220), NOT INCLUDED
Normal mode current consumption: ~1.5 mA
Interface: I2C
I2C address: 0x68
RAM memory: 56 bytes
Crystal frequency: 32.768 kHz
Time format: 24-hour / 12-hour with AM/PM
Accuracy: ~1 second/day (depending on crystal)
Operating temperature: -40 ~ 85°C
Dimensions: 41 x 23 mm
Pinout:
Pin
Description
VCC
5 VDC
GND
SDA
Communication via I2C interface
SCL
Communication via I2C interface
Usage:
Connect VCC to 5V and GND to the development board ground.
Connect SDA and SCL to the corresponding pins of the platform used (e.g. A4/A5 on Arduino Uno, pins 21/22 on Arduino Mega, GPIO21/GPIO22 on ESP32).
Install the CR1220 battery in the module holder to ensure time retention when the main power is absent.
Install the RTClib library from the Arduino IDE Library Manager.
On first use or after replacing the battery, set the initial time by calling rtc.adjust() in the initialization code.
Data is stored and read in BCD (Binary Coded Decimal) format from the internal registers of the DS1307 circuit.
Call rtc.now() to obtain a DateTime object with all available time fields.
WARNING! Although the module operates at 5V, when using it with ESP32 (3.3V) it is recommended to use a logic level converter to avoid damaging the microcontroller's data pins.