The recommended power-up sequence is to apply VCC first, followed by VBAT. This ensures that the internal voltage regulators are powered up correctly.
To ensure the oscillator starts up correctly, make sure that the X1 and X2 pins are connected to a suitable crystal oscillator with the correct load capacitance, and that the oscillator enable pin (OE) is set high.
The RST pin is an active-low reset input that resets the device when pulled low. It can be used to reset the device in the event of a fault or to initialize the device during power-up.
To configure the DS1318E+T&R for battery-backed SRAM operation, connect a battery to the VBAT pin, and ensure that the SRAM is connected to the correct address and data lines. The device will automatically switch to battery-backed mode when VCC falls below a certain threshold.
The maximum frequency of the clock output on the DS1318E+T&R is 32.768 kHz, which is the frequency of the internal oscillator.
DS1318E+T&R datasheet
by Maxim Integrated Products
