The Adafruit DS1307 Real-Time Clock Breakout keeps track of time even when your microcontroller loses power, with battery backup, 5V operation and support for Arduino, CircuitPython and Raspberry Pi. CR1220 battery not included. This is a great battery-backed real time clock (RTC) that allows your microcontroller project to keep track of time even if it is reprogrammed, or if the power is lost. Perfect for datalogging, clock-building, time stamping, timers and alarms, etc. The DS1307 is the most popular RTC - but it requires 5V power to work (although we've used it with 5V power and 3.3V logic successfully). Works great with an Arduino using Adafruit's RTC library or with a Raspberry Pi (or similar single board linux computer) Please note: This product does not come with a CR1220 coin cell battery. We recommend you purchase a coin cell battery to use with this product. The DS1307 is simple and inexpensive but not a high precision device. It may lose or gain up to 2 seconds a day. For a high-precision, temperature compensated alternative, please check out the DS3231 precision RTC. If you do not need a DS1307, or you need a 3.3V-power/logic capable RTC please check out our affordable PCF8523 RTC breakout. Features * Battery-backed real time clock (RTC) module with DS1307 chip * Maintains accurate time during power loss or microcontroller reprogramming * Ideal for datalogging, clock-building, time stamping, timers and alarms * Requires 5V power supply * Compatible with Arduino, CircuitPython, Raspberry Pi and Linux single board computers * Works with Adafruit's RTC library * Accuracy: may lose or gain up to 2 seconds per day * Coin cell battery (CR1220) not included * Simple and inexpensive RTC solution Specifications * Length: 25.8mm * Width: 21.7mm * Height: 5mm * Weight: 2.3g * Mounting holes are 2.2mm(0.086in) diameter, 25mm(0.98in) apart * This board/chip uses I2C 7-bit address 0x68 Revision History * As of October 2022 - we've updated this PCB with Adafruit Pinguin to make a lovely and legible silkscreen - you may get the new PCB or the older version with vector fonts - both are identical other than the fancy silkscreen. We also may have a slim metal or chunky plastic 32.768KHz crystal placed, both are functionally identical. Resources * Detailed guide Package Contents * 1x Adafruit DS1307 Real Time Clock Assembled Breakout Board CR1220 battery not included. https://elecena.pl/product/22713193/adafruit-ds1307-real-time-clock-assembled-breakout-board 2023-03-06 https://elecena.pl/product/22713193/adafruit-ds1307-real-time-clock-assembled-breakout-board 2023-12-27 https://elecena.pl/product/22713193/adafruit-ds1307-real-time-clock-assembled-breakout-board 2024-09-19 https://elecena.pl/product/22713193/adafruit-ds1307-real-time-clock-assembled-breakout-board 2024-11-29 https://elecena.pl/product/22713193/adafruit-ds1307-real-time-clock-assembled-breakout-board 2024-11-30 https://elecena.pl/product/22713193/adafruit-ds1307-real-time-clock-assembled-breakout-board 2025-04-09 https://elecena.pl/product/22713193/adafruit-ds1307-real-time-clock-assembled-breakout-board 2025-08-05 https://elecena.pl/product/22713193/adafruit-ds1307-real-time-clock-assembled-breakout-board 2025-11-28 https://elecena.pl/product/22713193/adafruit-ds1307-real-time-clock-assembled-breakout-board 2025-11-29