TMP411-Q1: question about "series resistance cancellation "

Hi Jay,

1. The feature 'Series Resistance Cancellation' eliminates measurement errors caused by the Rs shown in the diagram. 

2. It's common practice to place the Rs and Cdiff near TMP411.

3. Rs is not required for operation. In some cases, Rs and Cdiff can minimize noise found in the end equipment. The resistance is specified as 3kOhm max, but TMP411 will not eliminate all error up to 3kOhm, see Figure 4 and 5. Note that series resistance is the total loop resistance including the sum of both Rs resistors.

4. The implementation of Series Resistance Cancellation is proprietary, confidential. 

5. The remote junction is excited using a current source, and the voltage is measured by the sensor. The excitation currents, cycle timing and voltage operating range are all constants in the design. The voltage developed across the junction must settle within the cycle time to properly acquire the signal with the internal ADC. Excessive resistance will also push the voltage beyond the ADC's operating range. 

thanks,

ren

Hi,Ren

Thank you for your timely response.   

Jay, I'm not sure I understand your question, but there aren't any formulas associated with question 3.

thanks,

ren