Using 30M as a crystal is /maybe a problem : many crystals (over 20M or so) are made as overtone crystals, most 3. harmonic, so your 30M crystal might be a 10M crystal, thats used on 3. overtone.

If using such a crystal in standard oscillator circuit, it will run at 10M.

So better stay with lower (=standard) frequency crystals, 8 or 16 MHz , and you have a reliable clock.

If you need 30 or 40 M oscillator (why ? ) , then be sure to have not a model for use at overtone and have the load caps very small, to get it running at all.

mƎALLEm

ST Technical Moderator

Hello,

Is it the same behavior as the other thread ?

If yes start by reviewing the compatibility of the crystal by referring to the AN2867 and calculating the gain margin:

Do you get the gain margin > 5 based on what do you have in the HW?

what do you mean exactly by lagging? running at low frequency?

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Andrew Neil

Super User

@ChaitanyaParate wrote:
I am using 30 Mhz crystal oscillator, .

Do you mean a crystal oscillator - or just a crystal ?

Difference between just a crystal, and a crystal oscillator.

@ChaitanyaParate wrote:
it doesn't work properly

What, exactly, does that mean:

fails to oscillate at all ?
does oscillates, but at wrong frequency? If so, what frequency?
bursts into flames ?
other ... ?

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.