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AD7797/AD7796 doesn't work with 120 Ohm bridge sensor

Question asked by Ivan-Rusov Employee on Oct 22, 2013
Latest reply on Oct 22, 2013 by harryh

Hi,

 

I have a request regarding to AD7797/AD7796. You can see it below.

 

AD7797/AD7796 is used for measuring signal from bridge sensor. Wrong ADC data (overflow, offsets, etc.) occurs when 120 Ohm bridge sensor (strain gage) is connected to ADC. 350 Ohm bridge sensor works fine with AD7797/AD7796. 3.5 kOhm sensor also works fine. 120 Ohm bridge sensor works fine with another ADC AD7195, but AD7195 has much grater power consumption than AD7797/AD7796, so AD7195 can't be used in current application. Using 120 Ohm bridge sensor is mandatory in this application.

 

Could you please explain me a nature of this phenomena? Did you observe it before? Any recommendations would be great. Thank you in advance.

 

Regards,

Ivan

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