What is the actual purpose of changing the ADC clock frequency?

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I do have a SAM E70 Xplained development board.

When I was looking at the ADC function, I saw that the ADC clock frequency can be varied between pclk/2 to pclk/512.

I really want to know why we need to change the frequency of ADC conversion?

Why don't we fix it at the highest frequency available?

 

In my case, my pclk is 150MHz.

My requirement is to sample AC voltage.

 

Can anybody help me with this?

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Silly beans are always silly
:)

Last Edited: Thu. Oct 27, 2016 - 11:07 AM
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Your pclk is 150MHz. What do you do if your pclk is 10MHz? The adc is timing sensitive as it uses a charge balancing technique. Thus is doesn't work too well if you clock it too fast or too slow. Just like Goldilocks and the three bears - it has to be just right.

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Well, that explains something.

Thank you very much.

I'll be back to clear more silly doubts of mine.

Silly beans are always silly
:)