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AD7124-4 - Shared external reference

We have an application with 4 RTDs, each being measured by individual AD7124-4 devices (4 converters total). We'll also be using an ADR4525B external reference for improved accuracy.

Assuming that the internal reference buffers are enabled in each converter, and the reference output is bypassed according to data sheet recommendations, is it a reasonable design practice to share one external reference among 4 converters?

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  • Hi,

    It is possible to share one external reference such as ADR4525 to 4 x AD7124-4 identical converters. Just take note that the internal reference buffers for all 4 converters should be enabled to reduce reference errors. Even though it's possible, you should also need to consider the ratiometric configuration of the RTD if you target to have a high accuracy output. We have an available RTD calculator (https://www.analog.com/en/products/ad7124-4.html#product-tools) to give you a guide on the ratiometric configuration of RTDs and instead of using IC reference it uses reference resistors. Try exploring the RTD calculator provided in the link above, it will guide you through your RTD system design. 

    I have a question about your RTD application. how many wires does your RTD sensor have?

    Regards,

    Andrei 

Reply
  • Hi,

    It is possible to share one external reference such as ADR4525 to 4 x AD7124-4 identical converters. Just take note that the internal reference buffers for all 4 converters should be enabled to reduce reference errors. Even though it's possible, you should also need to consider the ratiometric configuration of the RTD if you target to have a high accuracy output. We have an available RTD calculator (https://www.analog.com/en/products/ad7124-4.html#product-tools) to give you a guide on the ratiometric configuration of RTDs and instead of using IC reference it uses reference resistors. Try exploring the RTD calculator provided in the link above, it will guide you through your RTD system design. 

    I have a question about your RTD application. how many wires does your RTD sensor have?

    Regards,

    Andrei 

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