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ADA4841 Input voltage headroom

Question asked by LMagalhaes on Nov 28, 2016
Latest reply on Nov 28, 2016 by harryh

Hi there,

 

I'm building a precision voltage generator and I'm using a DAC to drive the ADA4841 which is in a voltage follower configuration.

 

Previously it was the ADA4807, but it had some issues like: powering the unit from the USB and batteries would have an impact on the voltage output (deviation of 2~4 mV) and it was susceptible to any hands being near the circuit or the cables. When it was changed to the ADA4841, these problems went away. Maybe because this one is unity gain stable while the other one wasn't? I would still like to understand why I had these problems.

 

But, my question is the following: With the ADA4807 it was possible to have a voltage swing of 100mV to 4.5V on the input and have the same output voltage swing. With the ADA4841, it's only possible to go up to 4.2V. Is there any part replacement for this opamp which will allow the output voltage to go up to 4.5V ? The opamp is being supplied +/-5V.

 

Thanks,

 

Luís

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