Looking for a low-power alternative to MHz oscillators? Now, system designers have new lower frequency options based on programmable MEMS timing technology. This technology is ideal for industrial sensor applications because of its low frequency range, low power consumption, and resilience to radio-frequency interference (RFI) and mechanical stressors.
Traditionally, system designers have been limited to very few frequency options if they wanted less than a megahertz output frequency. With conventional quartz devices, the crystal resonator is cut from the blank material in a specific size, angle and shape to achieve each frequency. Due to manufacturing constraints, quartz vendors select a limited number of frequencies to support, especially in the lower frequency range.
In contrast, MEMS resonators are based on a standard resonator configuration. The resonator is paired with an oscillator IC/PLL and the output frequency is generated by programming the PLL to different multiplication values. This enables a very wide frequency range with six digits of accuracy.
The MEMS-based µPower SiT1569 oscillator is a perfect example and choice for industrial sensor applications because of its low-frequency options that range between 1 Hz and 462 kHz. This device draws less than 3 µA at 200 kHz. And if you need higher frequency options, the SiT1576 oscillator operates up to 2 MHz. The operating supply voltage is between 1.8V and 3.3V ±10%, and start-up time is less than 300 ms over temperature.
MEMS technology provides robustness against shock, vibration, and RFI. Resistance to mechanical force is due to the miniaturization of MEMS. The mass of a MEMS resonator is 500 to 3,000 times smaller than a quartz resonator. This is very significant because energy equals mass x acceleration. The same amount of stress acceleration (shock or vibration) has a much higher impact on a bulky quartz resonator as compared to a MEMS resonator. The SiT1569 and SiT1576 oscillators are guaranteed to be immune to 20,000g shock and 70g vibration.
Both parts are immune to shock/vibration and RFI