RTC 3 Click carries BQ32000, a real time clock with an integrated trickle charge circuit for automatic switchover to a backup power supply (the circuit maintains the backup charge with an onboard super capacitor). The clock frequency is derived from an onboard 32.768KHz oscillator. RTC 3 Click communicates with the target board microcontroller through mikroBUS I2C lines: SCL, SDA. In addition, the INT pin serves as a configurable interrupt output. The board is designed to use a 3.3V power supply only.