ADS1284: Bandwidth Noise

Mark Philip Felipe

Part Number: ADS1284

Hi Team,

Have found that the datasheet shows the PGA noise (V/sqrt(Hz)). However, we also need the specification of the noise BW of the ADC itself. We have checked that the filter is based on a SINC5. But, it never shows the value of the noise.

We would like to know what is the aproximation of the Bandwidth noise, depending on the sample rate parameter.

Thank you.

-Mark

over 2 years ago

0 Cole Macias over 2 years ago

TI__Mastermind 18900 points

Hello Mark,

Thanks for posting on the forum. Let me check with the team on this one.

Just so I understand, the customer's intent is to understand the PGA noise separately from the ADC + PGA noise spec given in tables 1-4 in the datasheet?

Best,

-Cole

0 Mark Philip Felipe over 2 years ago in reply to Cole Macias

TI__Genius 9745 points

Hi Cole, yes this is correct.

0 Cole Macias over 2 years ago in reply to Mark Philip Felipe

TI__Mastermind 18900 points

Hello Mark,

I was able to derive the ADC noise spectral density from table 3. This is applicable for all sample rates.

PGA Spectral Noise density [nV/sqrt(Hz)] = ~5.3

ADC Spectral Noise density [nV/sqrt(Hz)] = ~58

This is under the assumption that the customer is using the FIR filter, as it will be the dominant roll off. In addition, this is for the high resolution mode with chopping on.

Let me know if these assumptions are not valid and I can recalculate.

Best,

-Cole

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ADS1284: Bandwidth Noise