A simple RC circuit with a 1kΩ resistor and a 10nF capacitor is recommended to ensure a clean power-on reset. This circuit should be connected between VCC and GND, with the capacitor connected to the VCC pin and the resistor connected to the GND pin.
To ensure that the oscillator starts up correctly, it is recommended to add a 1kΩ resistor between the XIN pin and VCC, and a 1kΩ resistor between the XOUT pin and GND. This helps to stabilize the oscillator and prevent it from oscillating at an incorrect frequency.
The maximum clock frequency that can be used with the PCF8563TS/5 is 32.768 kHz. This is the frequency at which the internal oscillator is designed to operate, and it is not recommended to exceed this frequency.
To configure the PCF8563TS/5 to generate a 1Hz clock signal, you need to set the clock divider to 32768 (which is the default value). This can be done by writing the value 0x00 to the Clock Divider Register (address 0x0E). You can then use the CLKOUT pin to output the 1Hz clock signal.
The VBAT pin is used to connect a battery or a supercapacitor to the PCF8563TS/5. This allows the device to maintain its internal clock and calendar information even when the main power supply (VCC) is disconnected or powered down.
PCF8563TS/5 datasheet
by NXP Semiconductors
