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AD7606 Error Budget

Question asked by jeffadams on Feb 19, 2016
Latest reply on Feb 25, 2016 by jcolao

Hi Folks,


Newbie question - please be gentle :-) I am having to pick up a problem, and as usual, time is pressing.


The question is for an 8 channel AD7606, set up for the +/- 10 V range.It's being driven from an active, single-ended transducer - in fact a 741 op-amp is driving the input. The Vx leg has a 3K3 resistor in series, the VxGnd pin is strapped to ground. ( There is a 3K3 resistor present in the VxGnd line, but it has been shorted by an external layout fault. )


In operation, the expected input is very low frequency, and has a range of 0V to +5V.


So - given a reasonably simple layout - how do I go about expressing the total expected conversion error?


The reason I ask, is because I also have an input, driven via a simple, single ended resistive pre-scaler, which is producing about 100 * LSB of conversion error at an ADC input voltage of +8.5 V. This is quite a long way out from the data sheet, so I am assuming that the total error budget depends on circuit layout as much as the internals of the conversion process.


How does one approach the issue of conversion error budget, especially when you've been presented with a 'less than ideal' circuit.


Kind regards