Arduino UNO and Nano CH340G Schematics

Other Hardware General Electronics
61

Hello again, I have a couple of questions to ask:

  1. What is the difference between a crystal oscillator (often 2 pins) and a ceramic resonator (often 3 pins)?
  2. Is it true that a ceramic resonator doesn't need 2 extra caps, like the ones with the value of 22pF and usually needed for a crystal oscillator?
  3. Which is better, ceramic resonator or crystal oscillator?
62

The following links may help:

63

So a crystal oscillator is the same thing as a ceramic resonator?

64

Then, why are people still using crystal oscillators when there's a smaller but same functionality option (ceramic resonators)?

65

Is your Google broken? If you google this it's explained in every way you want - functional/superficial, with technical detail etc.

66

Ye, I don't understand all of it

67

Crystal oscillators are typically significantly more accurate. They're also not necessarily much bigger including the caps. 0102 caps are pretty small and crystals also come in very small SMT packages.

For your Nano you could use either. It doesn't matter much unless you require specific timings that a ceramic oscillator can't provide.

Then search for what you don't understand and learn about it...

68

Quartz crystals are accurate (often 20ppm or so), and need load caps. Ceramic resonators are poor frequency stability (5000ppm or worse), the three-pin ceramics but have caps built in and thus need a ground pin for them.

Usually - the datasheet for the particular device is the place to check details like this though.

Define "better" - it could mean "cheaper" to one person and "more accurate" to another.

These days MEMS oscillators are also starting to appear, basically micro-mechanical oscillators using silicon, and these are as good/better than quartz IIRC - but still much more expensive.

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In Performance

70

But, not that accurate?

71

For UNO too?

72

Like a CH340G IC?

Cuz, the ATMEGA328P often uses the ceramic resonators
And the CH340G often uses the quartz oscillators

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Are external caps a "Needed Component" for the Ceramic Resonators?

Because on MY Arduino UNO SMD Clone Board
There are still 2 caps for the ceramic resonator for the atmega328p...
And for the CH340G uses the quartz oscillator with 2 caps

And, on the ORIGINAL Arduino UNO DIP Board as well as the SMD ones
The ceramic resonator for the atmega328p doesn't use those 2 caps
And for the atmega16u2 uses the quartz oscillator with 2 caps

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Not for three-pin ceramic resonators. I thought I said this?

Is it a 2 pin or a 3 pin resonator? If its 2 pin if can't have two caps to ground as it doesn't see ground.

Anyway I'd pretty much always use a quartz crystal or TCXO, the cost difference isn't much, and often you need accurate clocks.

75

3p resonator