Other Parts Discussed in Thread: ADC128S102, OPA4277-SP
I am currently using the ADC128S102 with a +5V0 analog supply to sample voltages that are operationally constrained to +5V0. However, the analog input signals can reach voltages up to +7V5 if an operational mistake is made. To protect against this, I used shunt Schottky diodes to clamp the input voltage to within 0V0 to +5V0. However, since the diodes have a forward drop of ~0V3, the clamping range is realistically 0V0 to +5V3. Since the upper limit of this range is exactly equal to the ADC128S102's VA+0V3 absolute maximum input voltage, the input voltage is treading on the edge of damaging the part. Other A/D converters that I have looked at typically have an absolute maximum input voltage of VA+0V5 or VA+0V6, allowing for more "headroom" on the input when using Schottky protection diodes.
Aside from reducing the voltage that the Schottky diodes are clamping to (and thereby losing A/D range), what kind of input protection scheme do you recommend that allows for greater margins between the input voltage and VA+0V3?
Thank you,
Benjamin
