I have a customer asking the following questions:
I am performing an analysis to simulate the effect of an ionizing particle striking an op-amp feeding the ADS1281 ADC.
The ionizing particle can produce a transient at the output of the part causing it to go to one of the rails.
The transient can theoretically go above the ADC supply voltage leading to current conducting through one or more of the ESD diodes.
The transient is 10us wide with 10ns rise and fall times.
My question is; what is the rated current of the ESD diodes and the metallization inside the ADC?
A nice thing to have would be to know the minimum cross-sectional area of the metallization.
If I know that, I can use Black’s equation to estimate the lifetime degradation of the metallization.
If our transient does not exceed the current rating, I just put that in my report.
I know that the diodes on the input are simply ESD diodes and the absolute input voltage is AXDD + 0.1V which would not cause the diodes to conduct. Can the ESD diodes carry any current with the pulses described above? How would this affect the metallization?
Does the customer need to provide clamp diodes to make sure that the input voltage does not exceed AVDD + 0.1V?
Thanks for your help with this!
Richard Elmquist
