A family of clock ICs from Silego Technology integrates the tuning-fork crystal function into standard CMOS silicon. Most electronic systems contain a low frequency and ultra-low power 32.768kHz crystal for time keeping, system wake-up, or clocking an ultra-low power microcontroller. They will also contain a high frequency and performance MHz AT cut crystal for serial data communication, processors, RF transceivers, and high speed memory interface. The GreenCLK products are targeted at portable media players, camcorders, LCD and plasma TVs, smartphones, notebook, netbook, and desktop PCs, where the crystals are found together in a system. The company says that the ICs contain the first 32.768kHz silicon technology that is competitive with quartz in terms of size, power consumption, and frequency accuracy. It also claims that over-temperature accuracy from -40 to 85°C is improved by more than a factor of five, compared to a typical tuning fork crystal. During system sleep mode, the ICs consume less than 2.5µA while generating the 32.768kHz clock. The reduction in component count leads to a reduction in board estate as well as increasing mechanical robustness. The ICs are available in various formats with 4.2V support for direct connection to Li-Pol batteries, ML coin cell battery chargers, automatic power switching between battery back-up and active power modes, and output level controls from less than 1 to 3.3V.
