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Altera_Forum
Honored Contributor I
1,162 Views

MAX 10 Internal Oscillator

I am using a 10M2SCU169C8G demo board from QM Tech. Created an IP variation of the Internal oscillator which is supposed to output 116 Mhz. When I check the frequency, it is generating a frequency 74 Mhz 

instead. Can anyone tell me why this could be happening? There are only two outputs variation of the clock available. One is 55 Mhz and the other is 116 Mhz but, that is not what it's beinggenerated.
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3 Replies
Altera_Forum
Honored Contributor I
61 Views

Did you notice the min and max range specified along with the typical frequency?

Altera_Forum
Honored Contributor I
61 Views

As FvM said, for the internal oscillator for those parts the spec is min of 55MHz, max of 116MHz, typical value of 82MHz. You do not get to choose the frequency, all you know is it will be in that range. Your 74MHz part is perfectly normal. You may get one part that runs at 60MHz, another at 110MHz. All these are valid. 

 

If you need a more accurate frequency reference, you must use an external clock source, like a CMOS crystal oscillator with an accuracy of 25ppm to 100ppm.
Altera_Forum
Honored Contributor I
61 Views

 

--- Quote Start ---  

As FvM said, for the internal oscillator for those parts the spec is min of 55MHz, max of 116MHz, typical value of 82MHz. You do not get to choose the frequency, all you know is it will be in that range. Your 74MHz part is perfectly normal. You may get one part that runs at 60MHz, another at 110MHz. All these are valid. 

 

If you need a more accurate frequency reference, you must use an external clock source, like a CMOS crystal oscillator with an accuracy of 25ppm to 100ppm. 

--- Quote End ---  

 

 

Thank You for the response. I do have a 50 Mhz clock oscillator on the demo board and I am using it along with a PLL instance, to obtain the exact frequency I need. Did not realized though, that the internal oscillator has a range.
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