AD7176-2 REFOUT while using an external reference

Hi,

I am designing a board to read +-10V signals using the AD7176-2. I want to drive it by a AD8475 as on page 24, but to be able to use a single 5V supply, I will use an ADR444 supplying 4.096V as an external reference.

Now I am unsure about the state of REFOUT, and I cannot really find this specific part of information in the datasheet.

The example circuit on page 24 of the datasheet suggests that although an external reference is used, there is still 2.5V on the REFOUT pin. On the other hand, on page 27 of the datasheet it says:

The internal reference is output on the REFOUT pin after the REF_EN bit in the ADC mode register is set

So to be specific, here is my question:

When using an externel reference voltage, i.e. REF_EN is NOT set, will the 2.5V internal reference voltage still be available on the REFOUT pin?

Many thanks in advance,

DRies

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  • Hi DRies,

    I think that the circuit only emphasizes driving 2 differential inputs of the device but also shows how an external reference should be set up. But you are right - this may lead to confusion as it may look like the external and internal reference voltage are working together at the same time. Actually, if you look at its evaluation board, there are solder links before the REFOUT and REFIN pins. However, these are not shown here.

    Anyway, thank you for pointing this out. This will be noted.

    Regards,

    Johnny

Reply
  • Hi DRies,

    I think that the circuit only emphasizes driving 2 differential inputs of the device but also shows how an external reference should be set up. But you are right - this may lead to confusion as it may look like the external and internal reference voltage are working together at the same time. Actually, if you look at its evaluation board, there are solder links before the REFOUT and REFIN pins. However, these are not shown here.

    Anyway, thank you for pointing this out. This will be noted.

    Regards,

    Johnny

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