The recommended crystal oscillator frequency for the DS1305E+ is 32.768 kHz.
To ensure correct startup, the VCC pin should be powered up before the XTAL pin, and the RST pin should be held high during power-up.
The RST pin is an active-low reset input that resets the DS1305E+ when pulled low. It can be used to reset the device during power-up or to reset the clock during normal operation.
The clock on the DS1305E+ can be set by writing the desired time and date to the device's registers using the I2C interface.
The internal oscillator on the DS1305E+ has an accuracy of ±20 ppm over the operating temperature range of -40°C to +85°C.
DS1305E+ datasheet
by Maxim Integrated Products
