Author Topic: PIC oscillator circuite  (Read 6086 times)

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Offline Zedy

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PIC oscillator circuite
« on: December 26, 2010, 02:45:13 pm »
hey!
Some simple question:
A series resistor, Rs, may be required for AT strip cut crystals, it is said in pic datasheet.
So... if I have Series resistance of 100 ? in Quartz datasheet, is it the same resistance what pic datasheet is talking about?
 

Online Simon

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Re: PIC oscillator circuite
« Reply #1 on: December 26, 2010, 02:50:15 pm »
can you clarify the question  please ?
 

Offline Zedy

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Re: PIC oscillator circuite
« Reply #2 on: December 26, 2010, 02:59:24 pm »
can you clarify the question  please ?
sorry about my bad english,

but what I what to know is should I use this serial resistor?
 

Online Simon

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Re: PIC oscillator circuite
« Reply #3 on: December 26, 2010, 03:02:51 pm »
The datasheet for the resistor and pic in question should show you the common basic diagrams for setting the crystal up
 

Offline djsb

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Re: PIC oscillator circuite
« Reply #4 on: December 26, 2010, 03:39:47 pm »
Post the page from the PIC data sheet AND the crystal data sheet (in PDF form) or cut and paste the relevant data here if you can (as an image) and we will be a lot clearer as to your meaning. Thanks.

David
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 University Electronics Technician, London PIC,CCS C,Arduino,Kicad, Altium Designer,LPKF S103,S62 Operator, Electronics instructor.  http://debuggingrules.com/ Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime.
 

Offline migsantiago

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Re: PIC oscillator circuite
« Reply #5 on: December 26, 2010, 03:47:52 pm »
hey!
Some simple question:
A series resistor, Rs, may be required for AT strip cut crystals, it is said in pic datasheet.
So... if I have Series resistance of 100 Ω in Quartz datasheet, is it the same resistance what pic datasheet is talking about?

Hi!

The datasheet says you should consult the datasheet for the crystal you're using. The manufacturer should say what resistor you should use.

I wouldn't care so much about that resistor. I've never had to use it before.  ;)
« Last Edit: December 26, 2010, 03:55:40 pm by migsantiago »
 

Offline djsb

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Re: PIC oscillator circuite
« Reply #6 on: December 27, 2010, 12:47:38 pm »
These Microchip application notes may also be useful

• AN826, “Crystal Oscillator Basics and
Crystal Selection for rfPIC ®  and PIC ® 
Devices” (DS00826)
• AN849, “Basic PIC ®  Oscillator Design”
(DS00849)
• AN943, “Practical PIC ®  Oscillator
Analysis and Design” (DS00943)
• AN949, “Making Your Oscillator Work”
(DS00949)

David
David
Hertfordshire,UK
 University Electronics Technician, London PIC,CCS C,Arduino,Kicad, Altium Designer,LPKF S103,S62 Operator, Electronics instructor.  http://debuggingrules.com/ Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime.
 

Offline Zedy

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Re: PIC oscillator circuite
« Reply #7 on: December 27, 2010, 10:26:29 pm »

The datasheet says you should consult the datasheet for the crystal you're using. The manufacturer should say what resistor you should use.

I wouldn't care so much about that resistor. I've never had to use it before.  ;)
crystal datasheet is very poor, and doesn't say anything

Post the page from the PIC data sheet AND the crystal data sheet (in PDF form) or cut and paste the relevant data here if you can (as an image) and we will be a lot clearer as to your meaning. Thanks.


I usually don't care about oscillator, but this time I need very precise frequency.
 

Offline tecman

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Re: PIC oscillator circuite
« Reply #8 on: December 29, 2010, 11:49:18 pm »
I believe your datasheet data is referring to the equivalent series resistance of the crystal at resonance.  Usually a series resistor is not required, and as stated only for crystals with low drive power requirements.

I would not use a resistor.

paul
 

Offline Zedy

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Re: PIC oscillator circuite
« Reply #9 on: December 30, 2010, 12:23:44 pm »
I believe your datasheet data is referring to the equivalent series resistance of the crystal at resonance.  Usually a series resistor is not required, and as stated only for crystals with low drive power requirements.

I would not use a resistor.

paul


Thank you, it was, what I wanted to hear :)
 


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