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Scots Army Knife for electronics
BSD Zero Clause License
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ESD protection on Vio and Vsense pins #59

Closed whitequark closed 6 years ago

whitequark commented 6 years ago

FXMA108 gives us ESD protection on all I/O pins. However, what about the ADC and the LDO? In particular, the turned off LDO has the output in hi-Z state, which seems like it might have bad implications. Verify.

awygle commented 6 years ago

The LDO has 2 kV ESD tolerance, the ADC has 2.5 kV (on the pins in question, under the human body model). The LDO rail has 4.7 uF of capacitance, and the ADC has 12 nF before the input pin. Given that the human body model specifies 200 pF of capacitance, we have an effective 250 kV of tolerance, which should be plenty.

See https://irclog.whitequark.org/~h~openfpga/2018-05-22#22149898; for discussion with @azonenberg on this topic.

whitequark commented 6 years ago

Agreed.