A 0.1uF capacitor and a 1kΩ resistor in series can be used to create a power-on reset circuit for the DS1302. This ensures that the device is properly reset during power-up.
The DS1302 has an internal switchover circuit that automatically switches to the battery when the main power fails. However, it's recommended to add an external diode (e.g., 1N4148) between the VCC and VBAT pins to prevent backflow of current from the battery to the main power supply.
A 32.768kHz crystal oscillator with a 10pF capacitor in series and a 1MΩ resistor in parallel can be used to drive the X1 and X2 pins of the DS1302. This ensures a stable clock signal for the device.
To ensure accurate timekeeping, it's essential to use a high-quality crystal oscillator and to compensate for temperature variations. The DS1302 has a built-in temperature compensation circuit, but it's recommended to add external temperature compensation components (e.g., thermistors) for optimal accuracy.
The DS1302 is rated for operation from -40°C to +85°C. However, it's recommended to operate the device within a narrower temperature range (e.g., 0°C to 70°C) for optimal performance and accuracy.
DS1302ZN/T&R datasheet
by Maxim Integrated Products
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