2023.08.09 - Everyday Terms Engineers Need to Know About Crystals

Everyday Terms Engineers Need to Know About Crystals

Everyday terms Engineers Need to Know About Crystal Oscillators and Crystal Resonators

Crystal oscillators and crystal resonators are essential components used in electronic devices to generate precise and stable frequencies. As an engineer working with these components, it's important to understand some key terms that will help you select the right crystal for your application. Here are six everyday terms you need to know:

1. Fundamental Mode

The fundamental mode refers to the primary frequency at which a crystal is designed to vibrate. Most crystals operate in the fundamental mode, meaning they vibrate at their intended frequency. However, crystals can also be designed to vibrate at higher frequencies, known as overtones. These overtones occur near multiples of the fundamental resonant frequency, such as the 3rd or 5th overtone. When selecting a crystal, it's crucial to determine whether it operates in the fundamental mode or an overtone mode.

2. Operating Temperature Range

The operating temperature range specifies the temperatures within which a crystal can function reliably. Different applications may require crystals that can withstand specific temperature ranges. For example, automotive-grade crystals may have an operating temperature range of -40°C to 125°C. It's important to pay attention to the operating temperature range of a crystal to ensure it meets the requirements of your application.

3. Frequency Stability

Frequency stability refers to the ability of a crystal oscillator or resonator to maintain a consistent frequency output over time. It is expressed in parts per million (ppm) and typically measured at room temperature (25°C). The lower the ppm value, the more stable the frequency output. Crystals with higher stability are often used in applications where precision is crucial, such as GPS devices.

4. Frequency Tolerance

Frequency tolerance represents the acceptable deviation from the stated frequency across the entire operating temperature range of the crystal. It is added to the frequency stability value measured at room temperature. For example, a crystal with a frequency stability of 50 ppm and a frequency tolerance of 50 ppm means that the actual frequency may vary by up to 100 ppm across the entire temperature range.

5. Load Capacitance

Load capacitance refers to the capacitance value within the crystal oscillator or resonator. It is expressed in picofarads (pF) and determines the external capacitance required for the crystal to function optimally. The load capacitance can be a standard value specified on the datasheet or customized based on the specific requirements of the circuit design. Optimizing the load capacitance helps ensure the crystal's stable operation across temperature extremes.

6. Case Size

The case size indicates the physical dimensions of the crystal package. It is typically expressed as length x width x height (e.g., 5.0mm x 3.2mm x 0.8mm). Additionally, the case size may specify the number of pads (2 or 4) and the package type, such as ceramic, plastic, glass weld, or epoxy weld. Engineers often refer to case sizes using industry-standard codes like 2016 or 3225.

By familiarizing yourself with these everyday terms, you'll gain a better understanding of crystal oscillators and crystal resonators. Remember to consider fundamental mode, operating temperature range, frequency stability, frequency tolerance, load capacitance, and case size when selecting the right crystal for your electronic designs.

Note: The information provided is based on industry knowledge and best practices. For detailed specifications and further guidance, consult the manufacturer's datasheets and application notes.

For additional information, contact Harmony Electronics to discuss our crystal devices and how we can assist with your quartz frequency component needs. We encourage you to explore our website to learn more about our company, applications, and product offerings.

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