{"title":"Adafruit PCF8523 Real Time Clock Breakout Board","handle":"adafruit-pcf8523-real-time-clock-breakout-board","url":"/products/adafruit-pcf8523-real-time-clock-breakout-board","description":"Keep track of time even when your project loses power or gets reprogrammed. This updated PCF8523 Real Time Clock breakout features STEMMA QT / Qwiic connectors for solderless I2C wiring, plus traditional breadboard headers. It works with both 3.3 V and 5 V power and logic, making it compatible with virtually any microcontroller or SBC.\n\nWorks with Arduino (using the Adafruit RTC library), CircuitPython, and Raspberry Pi or other single-board Linux computers. For higher precision (temperature-compensated), see the DS3231 Precision RTC. For DS1307 compatibility, see the DS1307 RTC Breakout.\n\nKey Features\n\n\nPCF8523 RTC Chip – Battery-backed real-time clock with I2C interface\n\nSTEMMA QT / Qwiic Connectors – Solderless I2C connection, compatible with SparkFun Qwiic\n\n3.3 V and 5 V Compatible – Works with both power and logic levels\n\nCR1220 Battery Backup – Keeps time for 5+ years on a coin cell (battery not included)\n\nBreadboard Friendly – Header strip included for breadboard mounting\n\nTwo Mounting Holes – For permanent installation\n\n\n\nNote: CR1220 coin cell battery and STEMMA QT cable are not included. The PCF8523 is not a high-precision device — it may lose or gain up to 2 seconds per day. For temperature-compensated accuracy, use the DS3231 Precision RTC.\n\n\nCompatibility\n\nArduino (Adafruit RTClib library)\nCircuitPython / Python\nRaspberry Pi and other Linux SBCs\nAny microcontroller with I2C support\n\n\nIdeal For\n\nDatalogging with accurate timestamps\nClock and alarm projects\nScheduled task execution\nSTEMMA QT / Qwiic I2C projects\n\n\nPackage Contents\n\n1× Adafruit PCF8523 Real Time Clock Breakout, fully assembled and tested\n1× Header strip for breadboard mounting\n\n\nResources\n\n\nPCF8523 RTC Learn Guide – Code, libraries, schematics, and wiring diagrams\n\nWhat is STEMMA QT? – Introduction to the STEMMA QT connector system\n","vendor":"Adafruit","product_type":"physical","in_stock":true,"options":[],"variants":[{"id":2930,"title":"Default Title","sku":"AF-5189","price":10.11,"on_sale":false,"in_stock":true,"available_quantity":75,"option1":"Default Title"}]}