The S-35390A is a low-current-consumption 2-wire CMOS real-time clock IC that features a wide operating voltage range (1.3 V to 5.5 V) and can be driven on a variety of supply voltages, from a main supply to a backup supply. The time keeping current consumption of 0.25 µA and minimum time keeping operation voltage of 1.1 V enable greatly increased battery duration.
In a system that operates on a backup battery, the free register incorporated in the real-time clock can be used for the user backup memory function. The user register can hold data on a supply voltage as low as 1.2 V (min.), so the data stored in the register before the main power supply was cut can be called any time after the voltage is restored.
This product also includes a clock adjustment function that enables wide-ranging correction of deviation in the frequency of the crystal oscillator at a minimum resolution of 1 ppm. Also, by combining this function with a temperature sensor, the clock adjustment value can be set in accordance with changes in the temperature, which makes it possible to realize a clock function that retains a high degree of accuracy regardless of temperature variation.