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High precision ADCs need a precision voltage reference.

The question is: If such a reference source can supply the current, can that voltage (after being fed through suitable LRC filters) be used for powering the chip? (Or vice versa - power the chip, then LRC, then reference input)

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Yes it can and here's an example: -

enter image description here

Vdd is 2.5V and the reference input can also be 2.5 volts. The VIO supply range also encompasses 2.5 volts.

I would feed the reference input first then tee off to the supplies through suitable filtering. Make your reference supply as "strong" as possible so that it doesn't get glitched by the current that is taken by the supply rails.

Even at 500 kSps the total power taken by the chip is 3.5 mW so it is do-able. Regards a suitable reference I have used an LTC6655 with an NPN transistor to give it a bit more drive capability - the LTC6655 has a sense pin and allows this quite easily: -

enter image description here

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  • \$\begingroup\$ Thanks. What sort of noise penalties, if any? \$\endgroup\$ Commented Sep 23, 2016 at 9:19
  • \$\begingroup\$ There can be noise penalties but it's down to ensuring that the peak current taken by the rails does not screw up the ref voltage. I used this once and didn't see a problem ( I had 16 ADCs sharing the same ref voltage as shown above) but I decided against it on risk alone and although all 16 ADCs still shared the ref I applied a seperate 2V5 supply for the power pins. \$\endgroup\$
    – Andy aka
    Commented Sep 23, 2016 at 9:36
  • \$\begingroup\$ Did this answer work for you @Dirk - if so, please consider formally accepting it. If not, can you explain why? \$\endgroup\$
    – Andy aka
    Commented Dec 7, 2016 at 14:12

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