• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 45 subscribers
  • Views 658 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.

trying 4 wire method on 2 wire RTD

Embedded World
Prodigy 170 points
Other Parts Discussed in Thread: ADS1247

I am trying to do 4 wire RTD measurement method on 2 wire RTD or thermistor.
as in picture attached. 

AIN0 is channel used as current source.
AN1 & AIN2 are differential channels across which measurement is done.
R3 is used put measurement in common mode level.

1. Question is when I use AIN0 as current source on power up, current will rush through capacitor across R1. (forget to mentioned its name in picture) 

Will it cause trouble in measurement?

2. So can I do 4 wire measurement like this for 2 wire RTD or thermistor?

 

 

  • 0
    TI__Guru** 113765 points

    Hi Embedded,

    Yes there will be a short period of time where there will be a rush of current when first applied, but the ADS1247 will not be adversely affected.  What you really want to do is place the resistors where they will do the most good where R1 and R2 are on the other side of the caps.  This will allow the resistors and capacitors to be a filter for anti-aliasing and to filter EMI/RFI.  This will also limit the rush of current when first turning on the IDAC.

    Best regards,

    Bob B