Have You Considered These Key Parameters For Your Board’s Timing Solutions?
Selecting a quartz tuning fork or a crystal oscillator for timing purposes requires careful planning to ensure your final design performs as expected. You cannot afford to miss critical parameters or select components that perform poorly. Engineers in the design community should consider these two recommendations when choosing products:
- Avoid components from distributors that are not authorized by a leading manufacturer.
- Seek out engineering support for board testing, component selection, optimization and more.
Relying on a highly knowledgeable company that builds superior electronic components can help you select products that prepare your project for marketplace success. When choosing crystals, you likely already have your eye on the most important parameters, including:
- Frequency.
- Operating temperature range.
- Frequency tolerance.
- Whether this crystal is recommended for your industry’s applications.
However, two additional metrics are critical for performance: load capacitance and equivalent series resistance.
What Is Load Capacitance?
Load capacitance is the amount of energy a particular electronic component can store. A crystal tuning fork has a particular capacitance measured in picofarads (pF). The circuit board that will eventually contain your quartz tuning fork also has its own capacitance from other components on the board. This is known as stray capacitance.
Overall load capacitance for a crystal integrated into a circuit board is the total amount of capacitance the crystal will experience when in operation.
Why Does Load Capacitance Matter In Timing Solutions?
To provide the stable, clean, precise signal that you depend on from a quartz crystal, the load capacitance of the crystal should be matched with the overall capacitance of the board, including stray capacitance, so your oscillator can operate by the correct signal strength.
If you match these effectively, you ensure that power is always consistent throughout an oscillator’s cycles. When energy levels are maintained, you can limit power fluctuations that affect your crystal’s stability performance.
Use this load capacitance calculator to choose the right crystal component. First, plug in a crystal’s load capacitance from the datasheet provided by the manufacturer. Then, plug in the amount of stray capacitance from your board (typically between two and five pFs). The value calculated from these numbers will help you choose a component.
What Is Equivalent Series Resistance?
Equivalent series resistance (ESR) refers to how much energy resistance a component needs to overcome to function as expected. In the case of a tuning fork crystal or another quartz crystal used for oscillation, ESR refers to how much resistance must be surmounted before its resonating frequency occurs and can be maintained.
On a manufacturers’ datasheet for a crystal you are considering for your project, the ESR number is likely expressed in ohms (Ω) for Mhz and K ohms for tuning forks.
Why Is ESR Important For Timing Solutions?
In any quartz oscillator, knowing its equivalent series resistance parameters gives you a sense of how you must design the circuit to ensure that the oscillator can resonate and emit the precise frequency you expect. If the ESR is too high, the oscillator may not resonate at all.
Understanding how to compensate for ESR is particularly important for applications built for industries that intend to use as little power as possible, so as not to deplete the battery. For example, remotely deployed devices or personal devices typically desire low power consumption from components.
Are There Any Other Tools To Use When Selecting Crystals and Other Timing Solutions?
Beyond the load capacitance calculator, other resources can help you choose frequency-control components:
- Some frequency-control manufacturers have a parametric search tool that allows you to select your parameters and requirements to determine what products they have available for your project.
- Select your tolerance requirements and operating temperature with this calculator to determine the stability shift per second, among other calculations.
- Test your components’ stability with this PPM to Hz calculator to determine the frequency variation of any given crystal during operation.
Where Can I Find Engineering Support When Selecting My Timing Solutions Or Building My Board?
An industry-leading manufacturer of frequency-control components, including quartz tuning forks and crystal oscillators for timing, should offer engineering support to enhance your projects’ quality. Whether you need help determining load capacitance or ESR, having an experienced partner on your side provides additional benefits you cannot recreate on your own.
Look for support services like:
- Product samples.
- Product selection.
- Recommendations for how to approach board layout.
- Board testing.
- Board optimization.
- And much more.
Continue learning about the most critical aspects of frequency-control, starting with these resources:
Understanding Load Capacitance and Equivalent Series Resistance was last modified: November 14th, 2024 by