ADS114S08: AD conversion value fluctuates greatly when PGA is turned on

Ryu Yamashita

Part Number: ADS114S08

Tool/software:

Hi team,

I am using EVM to measure AD values, but only when I turn on PGA, the amplitude of the AD conversion values increases.
When the actual input is 1V, stable results are obtained when the PGA is turned off, but when PGAGAIN is set to 1, the result fluctuates greatly.
Are there any possible causes?

Best Regards,
Ryu.

7 months ago

0 Bryan Lizon86 7 months ago

TI__Guru 51776 points

Hi Ryu Yamashita,

Can you please show us how your signal source is connected to the ADC / EVM? It is possible you are violating the PGA common-mode range requirements, this is certainly true if you are measuring a single-ended input voltage.

-Bryan

0 Ryu Yamashita 7 months ago in reply to Bryan Lizon86

Genius 3600 points

Hi Bryan,

Where is the common mode range of the PGA described?
I could not find it from the datasheet.

Best Regards,
Ryu.

+1 Bryan Lizon86 7 months ago in reply to Ryu Yamashita

TI__Guru 51776 points

Hi Ryu Yamashita,

I copied the relevant portion of the datasheet below. Ensure that you are meeting these requirements, otherwise you will get unstable results

-Bryan

Data converters

Data converters forum

ADS114S08: AD conversion value fluctuates greatly when PGA is turned on