5.9.8. Real-Time Clock (HPS)
The HPS system has a battery-backed real-time clock (RTC) connected through the I2C interface. The RTC is implemented using a DS1339 device from Maxim Semiconductor. The device has a built-in power sense circuit that detects power failures and automatically switches to the backup battery supply, maintaining time. The device uses an Energizer 357-303HVZ Lithium coin battery with a nominal voltage of 1.55V.