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LM4140: Application with Temperature sensors

Gabriel Santos Pinto
Intellectual 585 points
Part Number: LM4140
Other Parts Discussed in Thread: LM4040

Hello, I'm looking to build an interface circuit for a temperature sensor, probably a thermocouple with a 1k or 10kohm resistor. 

I found this application note: 

regarding the use of this voltage reference with an RTD Sensor. 

From what I understand this document refers to the the use of a 100ohm RTD sensor, would a 1k or 10kohm thermocouple work well with this configuration? If not, is there anybody that can point me in the right direction?

Thanks in advance and regards,

Gabriel 

  • 0
    TI__Mastermind 19370 points
    Hi Gabriel,

    In short yes you can. The 100 Ohm was selected as an example for 1mA but a larger RTD resistor will just have a lower current. The only restriction is a resistor value that require the LM4040 to supply a current that is greater than 10mA.

    In theory the basics of an RTD sensor are from this application note and the configuration is a simplified configuration from 8.2.6 from the LM4040 DS.

    -Marcoo
  • 0
    Guru 140200 points
    Hi Gabriel,

    take care, the circuit shown in your link is highly simplified. To work in an industrial environment, especially with longer cables, you might need additional protection and filtering.

    Kai