Do delta-sigma ADC average a fast changing signal?

[atwoz]

I have been looking at some delta sigma ADC IC's, I need a 24bit delta sigma to get the average voltage of a signal that changes faster than the output rate of the delta sigma. Most delta sigmas have output rates of 100's of samples per second.

My question is: If my signal is a 10kHz sine wave, and I use a 24bit delta sigma that outputs 100 samples per second, will the delta sigma average the 10kHz sine wave so that in the output I will have the real average of the wave even when I'm only getting 100 samples per second?

Thanks!

[Dago]

Edit: wrong information. I retract my answer

[David Hess]

I have been looking at some delta sigma ADC IC's, I need a 24bit delta sigma to get the average voltage of a signal that changes faster than the output rate of the delta sigma. Most delta sigmas have output rates of 100's of samples per second.

Noise consideration means that they will be slower than that when delivering high resolution results.  Often the sample rate is a submultiple of 50 or 60 Hz (or both) so power line noise is rejected.

My question is: If my signal is a 10kHz sine wave, and I use a 24bit delta sigma that outputs 100 samples per second, will the delta sigma average the 10kHz sine wave so that in the output I will have the real average of the wave even when I'm only getting 100 samples per second?

That is exactly what will happen.  Delta-sigma converters are a type of integrating converter and average their inputs over the sample period.  This is in contrast to sampling converters which acquire a sample at one specific point in time.

[atwoz]

Thanks a lot David! I have another question. After a Delta-Sigma ADC outputs a sample (averaged) does the integrator reset for the next set of readings or will the next sample gets averaged along with the past readings?

[David Hess]

Thanks a lot David! I have another question. After a Delta-Sigma ADC outputs a sample (averaged) does the integrator reset for the next set of readings or will the next sample gets averaged along with the past readings?

This depends on the details of the converter.  Linear Technology makes "no latency" delta-sigma ADCs where every sample is independent.  Some other delta-sigma converters have a pipeline latency of like 3 samples making them more difficult to use with a multiplexor if you wanted to do that.