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Is there a way to use one multichannel sigma delta for design 4ch 3wire-RTD signal co

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For design single channel 3wire RTD simply we can use sigma delta ADCs like as ad7792 but for 4 channel 3 wire RTD design we need 8 current sources,
Is there a way to use one multichannel sigma delta for design 4ch 3wire-RTD signal converter?
 

Re: 4channel 3wire RTD design

The AD7792 3-wire compensation scheme looks quite nice at first sight. Reviewing the current source performance specification (e.g. 200 ppm TC) already chills the enthusiasm.

But appart from this specific problem, either if you use single or dual current source for your Pt100 circuit, why not feed them through spearate muxes to multiple sensors in a multichannel configuration?
 

Re: 4channel 3wire RTD design

The AD7794 is same as AD7792 but have 4 diff channels.

But how to multiplex Iref and Vref input pins between 4 RTDs?
I have only 5V in the circuit.
 

Re: 4channel 3wire RTD design

I don't exactly understand what you mean with Iref and Vref? Referring to the AD7792 input circuit, you would multiplex two current source outputs and two voltage sense inputs.
 

Re: 4channel 3wire RTD design

I need an IC that can convert 4 RTD to 16bit digital data,RTDs are 3 wired.

Please give IC part number that do above task.

ad7792 can do it for 1 RTD.
 

Re: 4channel 3wire RTD design

it seems there is no single IC solutions for 4channel RTD.
 

Re: 4channel 3wire RTD design

Hi, i am experiencing somewhat same issue but i want to multiplex 32 RTDs, for which i am using 32 channel multiplexer ADG732, but for the purpose of multiplexing excitation current into the RTDs i want to excite each RTD at a time, can u suggest me that is it possible for ADG732 to demultiplex 1mA from my current source to 32 channels?
 

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