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,