MCP7940 I2C Real-Time Clock IC (RTC) Breakout Board

Description

The MCP7940N is a Real-Time Clock and Calendar IC from Microchip, which includes a backup battery and has a 64 byte SRAM. The non-volatile memory can be used for storing things like calibration data.

The IC is able to keep track of hours, minutes, seconds day of the week, day, month and year. It is compensated to the year 2399. It includes 12/24 modes of operation. There is even a dual programmable alarm.

I2C communication is used to interface with the IC. It can powered from 1.8V to 5.5V, making it perfect for 3.3V and 5V systems. The backup battery voltage range is from 1.3V to 5.5V.

The operational current of the IC is very low, only using 1.2uA of current at 3.3V (low typical timekeeping current). The IC can operate from the backup battery with a current consumption of only 925nA (at 3V)!

For all the details, please see the official datasheet from Microchip. Our breakout board for the MCP7940N IC includes the I2C pins, power input and has an onboard battery holder (CR2035). It comes with a straight 4-pin header and a right-angle header. We leave the soldering up to you, to decide which type of connector you need.

Our design uses a highly accurate 32.768kHz crystal for time keeping. The crystal has a frequency tolerance of +/- 20ppm. The IC itself can be calibrated for tolerance offsets. It includes trimming of +/- 1ppm and range of +/- 129 ppm. All components used are able to be used with an operating temperature range of -40 degC to + 85 degC.

10kOhm pull-up resistors on the I2C communication lines are included on the board.

There is an Arduino library for the MCP7940: https://www.arduino.cc/reference/en/libraries/mcp7940/

Designed and made in the USA.  

You can purchase the board from our Tindie store: https://www.tindie.com/products/m12labs/mcp7940-real-time-clock-rtc-breakout-board/