How does the cock seed effect the Delta-Sigma ADC(CS552)?

[yangyunxing]

I don't know if the clock speed effect the delta-sigma ADC.
For example, I find someone use 131kHz crystal for CS5528, and it work well.
but CS5528 data sheet recommends the most common crystal:32.768kHz.
Further more, 131kHz crystal is very rare, so I want change the 131kHz
crystal to 32.768kHz crystal, I don't know if I can do this.

 

[laktronics]

Re: How does the cock seed effect the Delta-Sigma ADC(CS552)

Hi,
Crystal frequency of 32KHz should not matter, infact it appears to be better from ADC point of view, unless it has some other connection with rest of the interfacing circuit.
Regards,
Laktronics.

 

[yangyunxing]

How does the **** seed effect the Delta-Sigma ADC(CS552)?

Very thank you! Do you have a lot of application experience about Del-Sig ADC domain? I must be sure this, because I have only one chance to finish my design, or my boss must blame me. Besides, I don't yet understand " unless it has some other connection with rest of the interfacing circuit". Other connection means what?

 

[shiv_emf]

How does the **** seed effect the Delta-Sigma ADC(CS552)?

whr can i get more info abt Delta sigma modulator and ADC !
thanks
Shiv

 

[yangyunxing]

How does the **** seed effect the Delta-Sigma ADC(CS552)?

Shiv, I suggest you need not study basis knowledge of D-S modulator,because it is too difficult. what you should do is how to use it.

 

[laktronics]

Re: How does the cock seed effect the Delta-Sigma ADC(CS552)

Hi,
As you can see from the data sheet of the manufacturer, performance of the ADC is better at 32 KHz. The only effect of the crystal frequency is on the maximum conversion data word rate, which is not critical in strainguage like low frequency applications. The maximum data word rate reduces to 1/4 th when you reduce your crystal frequency to 32KHz. At the same time, with low frequency, the accuracy of ADC improves. Also, since the system is designed for higher frequency, the SCK clock rate will be fast enough, which should work for lower crystal frequency as well.

I wonder why you do not simply change the crystal and see what happens; I can assure you it will not explode.

Regards,
Laktronics.

 

[yangyunxing]

How does the **** seed effect the Delta-Sigma ADC(CS552)?

Laktronics, I'm sorry for my poor English. I often can't expain clearly what i want to say. i have understood your explanation. Very very thank you.

 

[laktronics]

Re: How does the cock seed effect the Delta-Sigma ADC(CS552)

Hi,
I have also not felt anything wrong with your language, it is quite clear to me. Finally have you tried to use with 32KHz crystal, is it working? Earlier I was only asking you if the same crystal was also used to provide clock to some of the logic and timing circuit on the board, in which case, you may not be able to change it.
Regards,
Laktronics

 

[yangyunxing]

How does the **** seed effect the Delta-Sigma ADC(CS552)?

Laktronics, I have used your advice, and my design will be finished soon. Many FBGA components are very trouble, I have spent a week to lay out. If the test result will be right, I will tell you.