What is the difference between these two crystals?

[Jack// ani]

Which Crystal?

Hi all,

What is the diffrence bwtween these two crystals? I have seen both of them are used to clock up uC, which one is a more better one?

Thanks

 

[IanP]

Re: Which Crystal?

Really not much difference as far as microcontrollers are concerned. I prefer low profile crystals ..

 

[glenjoy]

Which Crystal?

Any of the two can do as long as their specification with reference to functionality is the same.

If my post helped you, instead of saying thank you here in Edaboard, you can press the HELPED ME Button.

 

[Jack// ani]

Which Crystal?

Then the small one is far better because it is compact! Anybody know the real reason of having these to different pakages?

 

[gidimiz]

Re: Which Crystal?

Hi,

As every one said, both are the same. The package is called HC-49 for both of them. Both of them have the same material.
The large one is: HC-49/U Package, 1.8432 MHz - 200 MHz
The small one is: HC-49/US Low-Profile Package, 3.6 mm High, 3.5 MHz - 70 MHz
And even smaller: HC-49/US Low-Profile Package, 2.5 mm High, 8.0 MHz - 70 MHz
So you can see that the larger one you can get it in a wide range of frequancy and if you have a project that you need to change the OSC then you have to remember to keep the enclosure high enough.
More info on how the Crystal is built you will find here:
https://www.4timing.com/techcrystal.htm

Good luck.

 

[silvio]

Re: Which Crystal?

Hi Jack// ani,

It doesn't matter the shape and size as long as it fits in your projects.
More frustating is when your crystal doesn't start oscilating and your micro seems dead at power up. Read this application note from Atmel site which explains how an oscillator functions and which methods can be used to check if the oscillation conditions are met in order to ensure a good start-up when power is applied.

Sorry, I forgot to post the link:
http://www.atmel.com/dyn/resources/prod_documents/doc4363.pdf

Regards,
silvio

 

[IanP]

Re: Which Crystal?

The bigger on is just an artifact of the past and in the years to come they(crystals) will become even smaller ..
I called it "bigger one" but if you go back 5 or 10 years this "bigger one" was actually the "smaller one" as then the packages were much much bigger ..

THa same happend with almost all components ..

 

[stephen_h]

Re: Which Crystal?

In five years ago, HC-49/U is the cheapest one. Now it is no difference between HC-49/U and HC-49U/S.

For specification, I can see that they are no difference.

 

[ezpcb]

Re: Which Crystal?

either one will work, but I suggest active oscillators for newbies. Some experience is needed to make microcontroller's crystal circuit working stable. I think connect the shield of crystal to GND is a good idea, as well as putting a 2M resistor in parallel with the crystal.

mike

--------------------------------
www.ezpcb.com

 

[wolfheart_2001]

Re: Which Crystal?

hi,

i saw two types of connections of the crystal [serial]and[parallel], then what is the difference??

 

[gidimiz]

Re: Which Crystal?

Hi wolfheart_2001,

Here is the answer to your question.

Serial or Parallel resonance.

When a crystal is described as being a particular frequency series or parallel resonant, it is analogous to any other part being specified at a temperature of 20 or 25 degrees. The part is the same but the frequency has been determined under those defined parameters. At series resonance, the crystal appears as a series resonant RLC circuit with 0 phase shift, so to use it in an oscillator you need to provide the 360 degree phase shift needed. At parallel resonance, the crystal is predominantly inductive and with the external capacitors, provides 180 degrees of phase shift at the specified frequency. The other 180 degrees is provided by the inverting amplifier provided in the micro. The difference in frequency between series resonance and parallel resonance is about 0.05%

For more info, go to: http://www.tla.co.nz/xtal1.html

Good luck.

 

[wolfheart_2001]

Re: Which Crystal?

hi gidimiz

thank u, the link is v.good.

 

[irfansyah]

Re: Which Crystal?

In here, the smaller one is harder to find and a bit more expensive. I like the smaller one better, merely because of the compactness...