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Use of TL431 for voltage reference of AD7683

gigarashi
on Jan 12, 2017

Hi,

I am interesting to use TL431 voltage reference to generate 5V to be used in Vref input of AD7683.

This voltage reference has low noise voltage enough for AD7683?

I am asking because many voltage reference devices inform noise voltage parameter, normally in a specific range of frequency and in micro volts.

For example, ADR435 device, from Analog: Low noise (0.1 Hz to 10.0 Hz): 3.5 µV p-p @ 2.5 V output.

Unfortunatelly, this information does not informed in the TL431 datasheet. I tried TI, OnSemi, etc...

Regards,

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  • FormerMember
    0 FormerMember on Jan 13, 2017 12:28 AM

    I would not even consider the TL431 with a 16 bit ADC;  you are just throwing money away.

    The TL431 is a commodity reference, with 50 ppm/C tempco.  So after your temperature

    changes by 10 degrees, you have less than a 14 bit system.   There is a noise curve

    (fig 7) on the TI data sheet.   Integrate over your bandwidth.

    Depending on system cost target, look at the ADR3425 or the ADR4525 and everything

    in between.

    Harry

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  • FormerMember
    0 FormerMember on Jan 13, 2017 12:28 AM

    I would not even consider the TL431 with a 16 bit ADC;  you are just throwing money away.

    The TL431 is a commodity reference, with 50 ppm/C tempco.  So after your temperature

    changes by 10 degrees, you have less than a 14 bit system.   There is a noise curve

    (fig 7) on the TI data sheet.   Integrate over your bandwidth.

    Depending on system cost target, look at the ADR3425 or the ADR4525 and everything

    in between.

    Harry

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