ADS7953: Rsource impedance

Lilian Chang

Part Number: ADS7953

Hi Team,

In datasheet, Rsource is recommended <50ohms. My customer found when they set Rsource=0 ohm, the ADC captured data was not stable.

Why this impedance is necessary?

over 8 years ago

0 Evan Sawyer over 8 years ago

TI__Expert 3175 points

Hi Lilian,

The resistance is necessary to ensure stability at the input, as opposed to the input signal being connected directly to the 'charge bucket' capacitor (shown in the diagram you shared).

I recommend checking out the TI Precision Lab video titled "Introduction to SAR ADC Front-End Component Selection" for more information on why the charge bucket is needed.

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ADS7953: Rsource impedance