When ad7321 collects voltage, a spike voltage appears

[Malugu]

When AD7321BRUZ collects voltage, a spike voltage appears at the input every time it is acquired.

After the input is opened, the ripple voltage is shown in the following figure:





Can you explain this situation.

[KlausST]

Hi,

please use the link to the manufacturer internet site. There you get the latest and most reliable informations.

Spike:
This is caused by the "track and hold" capacitor and is quite usual for a SAR ADC.
Thus often a buffer OPAMP is recommended.
Read the datasheet "Track-and-Hold Section"

Klaus

[FvM]

You don't show what's connected to VIN0 and VIN1. The ADC inputs are usually driven by a low impedance buffer, otherwise charge injection of the sampling switches will be observed.