ADC sample & hold time / aquisition width

Robin Kienzler

Other Parts Discussed in Thread: TMS320F28016

Hello guys,

I have a question concerning the adc behavior of the TMS320F28016:

With the ACQ_PS bit it is possible to extend the acquisition width depending on the ADC clock. Is this time completely available for
charging the sampling capacitor of the sample & hold circuit?...or is it used for conversion too?

Thanks for your support.

over 14 years ago

0 MatthewPate over 14 years ago

TI__Guru* 80080 points

Robin,

This extension only applies to the sample and hold duration, the conversion phase of the ADC remains constant from the point the sample is complete.

Best,

Matthew

0 Robin Kienzler over 14 years ago in reply to MatthewPate

Prodigy 110 points

Thanks Metthew,

do I understand you correctly that the complete acquisition width t_SHis used for charging the internal capacitor?

If not, how long is the sampling phase and how long the holding phase within t_SH?

(This information is very important for dimensioning the input impedance of the adc pins)

0 MatthewPate over 14 years ago in reply to Robin Kienzler

TI__Guru* 80080 points

Your understanding is correct, the whole acquisition width is used to charge the sampling cap. From the naming convention I can now see how this is not as clear as I'd like it to be.

Best,

Matthew

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ADC sample & hold time / aquisition width