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AD8495 Input Filter - Resisistor Value

Question asked by AngelicaZ on Nov 8, 2017
Latest reply on Nov 24, 2017 by AngelicaZ

Hi!

I've been running simulations with AD8495, the circuit is similar to the Fig 29 in the datasheet, I implement a filter at the input. I noticed that as I change the resistor value of the low pass filter, I get a slight different output voltage. In the datasheet it is not mentioned anything about the impact of resistor value to the output voltage.

In the Application Note AN-1087, it says that for 780°C at the measurement junction, the actual output of AD8495 for a K type is 3.975V. I only get that voltage if the resistor of the filter is 2.4k, but it changes if I change the resistor in the filter. I don't understand if this drift error is to be expected in real life, or if the spice model of AD8495 just doesn't compensate to get a close linear fitting as depicted in Table 3 of the Application Note AN-1087. Will I get the output voltages of Table 3 in App Note, regardless of the resistor value in the input filter?

Can you please advice on this?

Thank you!

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