AnsweredAssumed Answered

AD7091 max analog input range ?

Question asked by ladu on May 16, 2016
Latest reply on May 20, 2016 by harryh

Hello,

I plan to use AD7091R-8  with VDD and Vdrive to 3.3V and use embedded 2V5 voltage reference.

some of the circuits i want to measure use drivers with low impedance and powered with 5V. Even if I can adjust operating scale of these circuits to 2.5V, I can not prevent these clipping to 5V during power-up down sequences or in case of circuits saturation due to HW failure. Connecting these circuits directly to ADC makes the risk of having a large current through power rail diodes high.

 

Thus here are my questions :

- I see on datasheet that each MUX inputs are limited to VREF  thus i assume a diode to VREF is connected on each lines ?

- if yes can I just put a series resistor in series on these lines MUX inputs ( let's say 2k5 wit a max VREF diode current of 2 mA) and use a buffer as a low impedance source follower between mux out and ADC IN ? will the ADC performances be degraded ?

 

thanks for the tips,

 

Laurent.

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