Capacitor value selection for crystal

[Murugesh_89]

Hi,
For the pic18f45k22 microcontroller, i want to use the 10MHz smd crystal.
What value of capacitor should be used in the crystal circuit for this case?

 

[FvM]

The datasheet knows the answer.

 

[Murugesh_89]

I have gone through the pic18f45k22 datasheet, it has nothing about this parameter.

 

[nagkiller]

The spec is on the datasheet of Crystal...

 

[FvM]

You are right, in contrast to previous datasheets, the 18F45K22 datasheet doesn't specify values. Instead it's referring to several application notes e.g. AN849 https://ww1.microchip.com/downloads/en/AppNotes/00849a.pdf

In a short, I would start with previously suggest 22 pF capacitors.

 

[thirunavukkarasu]

You may use 22 pf, 33 pf, or 15 pf.... No problem with these three i am using 33 pf.

This capacitor value is used for stabilizing only, it has no effect on the frequency of the crystal, so you can use any of these three values

 

[FvM]

This capacitor value is used for stabilizing only, it has no effect on the frequency of the crystal, so you can use any of these three values.

The capcitor value has a definitely an effect on the actual oscillation frequency, but the ppm range frequency variation caused by the capacitor can be ignored in most applications. If you however intend to use the primary oscillator for realtime clock purposes, you'll notice ppm variations.

The relation between external oscillator capacitors and crystal load capacitance specified in crystal datasheets is also explained in the Mircochip application notes.

 

[thirunavukkarasu]

use this capacitor in protious

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