• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 45 subscribers
  • Views 591 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

About the MUX of ADS1120 at Turbo mode

Tao_2199
Genius 5770 points
Other Parts Discussed in Thread: ADS1120

Hello,

 

My customer is asking about the MUX of ADS1120.

(1) They confirmed that the output error is lager after changing MUX.

(It is high compared to what they expect.)

(2) This issue is happened at first conversion.

(3) They are using on Turbo mode and PGA=enabled..

 

According to the thread(below) of ADS1120, It is described following about MUX.

https://e2e.ti.com/support/data_converters/precision_data_converters/f/73/t/402890

 

“What happens on a mux change is the register value is decoded and the mux disconnects from the previous input channels then connects to the new channels. 

Also, the digital filter is reset which actually starts a new conversion once the channels have switched.”

 

“What sometimes happens when using continuous conversion mode is the previous channel data has not been read out at the correct time.

The best method is to use an interrupt driven system where the data is read immediately after the falling edge of DRDY.

Then you can change the mux right after the data has been read.

At this point the next falling edge of DRDY should be the new mux position data.”

 

(Question)

(1) They are using ADS1120 at turbo mode and PGA=enabled.

Is there a possibility that the above problems occur in the same way in turbo mode?

 

Of cause, I think that it is needed to confirm their condition (register setting, code) and the behavior of issue.

Could you please give some comment and opinion or advice?

 

Regards,

Tao_2199

  • 0
    TI__Guru** 113765 points

    Hi Tao_2199,

    As I do not know all the register settings, nor have I seen the schematic it would only be a guess as to what might be happening.  If I could see a series of data showing the error it would be helpful.  It would also be helpful to know if the customer is using single-shot mode or continuous mode. 

    In turbo mode and at 2ksps (although the specific data rate is not specified), it is quite possible the customer is seeing analog settling after changing channels.  In this type of situation it may be helpful to either throw out the first few samples, or to use a small delay after switching mux channels and then send the START/SYNC command to restart the conversion.

    As far as the referenced post, there is a small possibility that the data is corrupted if an update should occur at about the same time as the data is about to be read.  However, I think it is more likely the case that there is some analog settling.  Again, the schematic and result codes would be helpful (as well as what code was expected.)

    Best regards,

    Bob B