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Stability of the 280mV Internal signal

Question asked by JonathanB on Jan 23, 2018
Latest reply on Mar 27, 2018 by Lluis

Hi, 

 

I'm currently working on a project involving the AD7779.

 

Channels 0-3 are used, 4-7 are disabled through CH_DISABLE register.

I'm using an external 2.5v Reference.

 

ODR is set to 0.5ksps

 

PGA Gain is set to 8 for every used channel, and the power mode is set to Hi-Resolution.

 

In the initialization sequence, I'm performing the offset adjustment then the gain adjustment using the internal 280mV differential signal.  Note that a digital reset is performed as per datasheet requests.

 

However, I see that this signal seems quite unstable, varying typically +/- 450 MSBs:

 

I couldn't find any clue about it's specifications / limitations.

Is this behavior expected for the 280mV p-p signal ?

 

Thank you very much!

 

Jonathan

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