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CN0172 Thermocouple Evaluation Board Register Settings

Question asked by alexc63 on Jun 5, 2014
Latest reply on Jun 10, 2014 by Lluis

Hi,

 

I am using the CN-0172 evaluation board using the AD7792 and the ADT7320 and 3 thermocouples - I am using T Type for my application. I am connecting the eval board to my own microcontroller, not the dev board supplied by Analog Devices. There is no reference to how the software supplied by Analog configures the hardware on the CN0172, and just have a few questions about how to configure the registers for the AD7792 ADC myself.

 

For the AD7792, should it be set to uni or bipolar mode for a thermocouple input?

 

Also what is a suitable gain and filter update frequency for this application?

 

The board will be powered by 3.3V. The temperature range will be between 10 and 60 DegreesC so will be looking at input voltages of 300uV to 2.5mV from the thermocouple. I am unclear what is a suitable gain for these input voltages, and how is this affected by the bias voltage?

 

From the schematic for the evaluation board, I will make the following assumptions. The internal voltage reference will be used; the internal clock will be used; bias voltage generator disabled as there is an external bias voltage of vcc/2 on each of the negative inputs; burnout currents disabled; excitation currents disabled.

 

Any help will be much appreciated.

 

Many thanks

 

Alex

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