Difference btw resonator and crystal oscillator

pls, what are the fundamental differences btw a resonator and crystal oscillator and which of them is preferable to use in PIC circuitry

folarinv said:

pls, what are the fundamental differences btw a resonator and crystal oscillator and which of them is preferable to use in PIC circuitry

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A resonator is cheaper (and usually includes internal capacitors), but a crystal is more accurate and stable.

If you don't need the absolute best accuracy, then a resonator is fine.

From what I've read a resonator also has a more stable frequency output over a wide range of temperatures whereas as crystal's output will vary more with temperate changes.

rackley said:

From what I've read a resonator also has a more stable frequency output over a wide range of temperatures whereas as crystal's output will vary more with temperate changes.

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the inverse is true

So what exactly is the resonator? Is is some kind of RLC circuit?

DigiTan said:

So what exactly is the resonator? Is is some kind of RLC circuit?

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Presumably, as it's called a "ceramic resonator", it's a slice of ceramic?, just as a crystal is a slice of quartz.

Also note the difference between the setup using a simple crystal with 2 caps and the external crystal oscillator. The simple crystal itself has both pins connected to the PIC. The PIC pumps it and it rings out at the desired frequency (probably a gross oversimplification). The oscillator has a crystal and its own driver and probably an output stage built into it, so it takes in 5v and just has a frequency output. The oscillator cannot generally be made to respond to the "sleep" mode the way a crystal can.

A ceramic resonator uses a ceramic element as a piezoelectric resonator instead of quartz and have some form of internal load capacitance resulting in a three pin case where the center conductor (I assume in all cases) goes to ground. Ceramic resonators, as far as I remember, have good temperature characteristics but only fair mechanical stability. Ceramic resonators are more stable than an RC but less stable than a crystal. They are an inexpensive alternative to crystals.
You need to decide how critical the accuracy of the timing needs are in your circuit, An RC is good if timing is no issue at all, use a resonator if you need some precision, use a crystal for most circuits, use a TCXO for good accuracy, and use a OCXO for high accuracy.