Abstract: Various embodiments of the invention relate generally to real-time clock circuit, and more particularly to systems, devices and methods of integrating two oscillators in one real-time clock circuit to generate accurate time of day over an industrial temperature range. A primary oscillator is employed to generate a first high precision clock while having a higher frequency and consuming more power; a secondary oscillator is employed to generate a second clock that has a low frequency and consumes less power, but may not meet the time accuracy requirement. When the real-time clock is provided with sufficient power (MSN mode), time of day is constantly tracked by the primary oscillator, but when the real-time clock is powered by a battery (SLEEP mode), time of day is tracked by the secondary oscillator while the primary oscillator is switched on at an update frequency to compensate errors in the time of day.