• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 45 subscribers
  • Views 217 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.

ADS1146

Dang heng
Intellectual 880 points
Other Parts Discussed in Thread: INA333, ADS1146

hi

I am using the ADC to measure bipolar signal from hall sensor. The hall sensor internal circuit is resistive bridge structure.

 

The output of hall sensor:

 

Sense+ = 1.5V + 20mVpp

Sense-  = 1.5V + 20mVpp

 

Previously, I used INA333 (the gain is set to 40) to offset, amplify, and convert to single-ended signal. The signal is then connected to single-ended ADC. However that ADC doesn’t have 50/60Hz noise rejection capability.

 

I checked ADC with 50/60Hz noise rejection capability from TI website and found ADS1146 has the fastest sampling rate. Is there any single-ended TI ADC with 50/60Hz noise rejection?  

What is the best external conditioning circuit for the hall sensor output to interface it to ADS1146. If I use INA333 to convert the signal to single-ended and connect to ADS1146, what should be the gain of the INA333 so not to exceed common-mode signal range of the ADS1146?

 

ADS1146 will be powered by 3.4V analog supply. I will use external reference voltage for the analog reference

Thank you!

  • 0
    TI__Mastermind 23275 points

    Hi Dang,

    did you think about interfacing the hall sensor directly to the ADS1146, without using the INA333?
    As the common-mode voltage of the hall sensor signal is already inside the correct range for the PGA inside the ADS1146 to operate properly you may not need the INA333. That way you would not have to convert the differential signal to a single ended one and the PGA could be used as your gain stage. Depending on the reference voltage that you are using you could set the PGA to a gain of 32 or 64.

    Most of our Delta-Sigma ADC's (those are the ones that offer 50/60Hz rejection) have fully differential inputs. Therefore you would loose 1 Bit of resolution when converting the signal to single ended first. Feeding a differential signal to the ADC will be the better approach.

    BTW: I assume Sense- = 1.5V - 20mVpp?

    Regards,