Contents
How to choose the best load capacitors for a crystal oscillator?
Most often the best starting point of selecting load capacitors for a crystal oscillator is the datasheet of the device being driven. To give an example, an ATMEGA328PB-MU Please note the 16Mhz crystal would be used in a 5V application.
What is the CS of a crystal oscillator?
CS is the total stray capacitance for one XTAL pin on the microcontroller. Let’s go ahead and pull the components used on the manufacturer’s demonstration board as an example, the ATMEGA328PB-XMINI Manufacturer’s specified Load Capacitance for this crystal is 9pF. Common Stray Capacitance values often fall in the 2pF to 5pF range.
When was the microchip crystal oscillator invented?
2002 Microchip Technology Inc. Oscillators are an important component of radio fre- quency (RF) and digital devices. Today, product design engineers often do not find themselves designing oscil- lators because the oscillator circuitry is provided on the device. However, the circuitry is not complete.
Why do I need an external MEMS oscillator?
One shortfall of crystal oscillators is mechanical shock/vibration can cause them to fail, in these cases it’s advisable to use an external MEMS oscillator. C1, C2 = 2* (CL) – Cstray. Any idea why these answers might be coming out different?
What should the capacitance of a crystal be?
If you want the crystal to oscillate as close as possible to the marked frequency, on average, you match up the total load capacitance to what the xtal maker has specified by specifying the two capacitors (usually they are both the same value, so you have only one degree of freedom).
Which is the correct value for load capacitance?
One crystal manufacturer defines it like this: Another website has this to show for an answer: Quite many seem to think that the load capacitance is the value the crystal manufacturer recommends for the external capacitors. This, to me, seems completely incorrect. (But, as it turns out, might still work perfectly ok).